Статті в журналах з теми "Acinetobacter baumannii, RNA binding protein"

Acinetobacter baumannii is a Gram-negative pathogen, known to acquire resistance to antibiotics used in the clinic. The RNA-binding proteome of this bacterium is poorly characterized, in particular for what concerns the proteins containing RNA Recognition Motif (RRM). Here, we browsed the A. baumannii proteome for homologous proteins to the human HuR(ELAVL1), an RNA binding protein containing three RRMs. We identified a unique locus that we called AB-Elavl, coding for a protein with a single RRM with an average of 34% identity to the first HuR RRM. We also widen the research to the genomes of all the bacteria, finding 227 entries in 12 bacterial phyla. Notably we observed a partial evolutionary divergence between the RNP1 and RNP2 conserved regions present in the prokaryotes in comparison to the metazoan consensus sequence. We checked the expression at the transcript and protein level, cloned the gene and expressed the recombinant protein. The X-Ray and NMR structural characterization of the recombinant AB-Elavl revealed that the protein maintained the typical β1α1β2β3α2β4 and three-dimensional organization of eukaryotic RRMs. The biochemical analyses showed that, although the RNP1 and RNP2 show differences, it can bind to AU-rich regions like the human HuR, but with less specificity and lower affinity. Therefore, we identified an RRM-containing RNA-binding protein actually expressed in A. baumannii.

Acinetobacter baumannii, a Gram-negative coccobacillus, is notorious for its involvement in opportunistic infections around the world. Its resistance to antibiotics makes treatment of infections challenging. In this study, we describe a novel response regulator protein, AvnR (A1S_2006) that regulates virulence-related traits in A. baumannii ATCC17978. Sequence analysis suggests that AvnR is a CheY-like response regulator and contains the RNA-binding ANTAR (AmiR and NasR transcription anti-termination regulators) domain. We show that AvnR plays a role in regulating biofilm formation (on glass and plastic surfaces), surface motility, adhesion to A549 cells as well as in nitrogen metabolism in A. baumannii . RNA-Seq analysis revealed that avnR deletion results in altered expression of more than 150 genes (116 upregulated and 42 downregulated). RNA-Seq data suggest that altered biofilm formation and surface motility observed in the avnR deletion mutant is likely mediated by previously unknown pathways. Of note, was the altered expression of genes predicted to be involved in amino acid transport and metabolism in avnR deletion mutant. Biolog phenotypic array showed that deletion of avnR hampered A. baumannii ATCC17978’s ability to metabolize various nitrogen sources, particularly that of glutamic acid, serine, histidine, aspartic acid, isoleucine and arginine. Taken together our data show that AvnR, the first ANTAR protein described in A. baumannii, affects virulence phenotypes as well as its ability to metabolize nitrogen sources.

The increasing emergence of multidrug-resistant Acinetobacter baumannii brings great threats to public health. Minocycline is a kind of semisynthetic derivative of the antibacterial drug tetracycline and is often used to treat infections caused by multidrug-resistant A. baumannii with other antibiotics. However, minocycline-resistant A. baumannii appears constantly. To rapidly explore the response of A. baumannii to minocycline stress, RNA-seq was carried out to compare the difference in the transcriptome of A. baumannii ATCC19606 in the presence or absence of minocycline. The results showed that 25 genes were differentially expressed, including 10 downregulated genes and 15 upregulated genes, and 24 sRNA were upregulated and 24 were downregulated based on the filter criteria (Log2FC > 1 or <−1 and FDR < 0.05). RtcB family protein and ABC transporter ATP-binding protein were upregulated by 2.6- and 11.3-fold, and molecular chaperone GroES, chaperonin GroL, class C beta-lactamase ADC-158, amino acid ABC transporter permease, and APC family permease were downregulated by at least two-fold in the presence of half-MIC minocycline. The differentially expressed genes are mainly involved in the stress response, the GroES/GroEL chaperonin system, and transport metabolic pathways. sRNA 1248 was significantly upregulated, and sRNA 1767, 5182, and 6984 were downregulated in a rapid response to minocycline. These results provide insights into the adaptive mechanism of A. baumannii to minocycline.

Acinetobacter baumannii is known for its virulence in severely ill, hospitalized patients and for exhibiting multidrug resistance. A. baumannii infection treatment poses a serious problem in clinical environments. The outer membrane protein A (OmpA) of the Acinetobacter genus is involved in bacterial virulence. Regulatory factors of OmpA in the post-transcriptional stage have been previously identified. However, the regulatory factors that act before the transcriptional stage remain unclear. We investigated the A1S_0316 gene that encodes a putative transcription factor for OmpA expression in A. baumannii. A1S_0316 was purified and examined using size-exclusion chromatography, which revealed that it forms an oligomer. The binding affinity of A1S_0316 to the OmpA promoter region was also examined. We compared the binding affinity to the OmpA promotor region between A1S_0316 and the AbH-NS protein. A1S_0316 showed higher binding affinity to the OmpA promotor region than did H-NS. We examined the regulatory effect of these proteins on OmpA expression in A. baumannii using real-time qPCR and various in vitro tools. Our results indicated that A1S_0316 acts as an anti-repressor on the promotor region of the OmpA gene by inhibiting the binding of the AbH-NS protein. This study was the first demonstration of the transcriptional regulation of OmpA expression.

Carbapenems are considered as the most effective antibiotic against Acinetobacter baumannii infections, as the pathogen has a resistance to the most of the other beta-lactam antibiotics; however, recent studies proved that this pathogen has developed resistance to carbapenems, as well. Therefore, development of novel therapeutics targeting A. baumannii resistant strains is an urgent global requirement. One of the causes responsible for this bacterial resistance against beta-lactam antibiotics is the decreased strength of interactions between A. baumannii Penicillin-Binding Proteins 1A (PBP1A) and carbapenems. Therefore, the aim of this study is to design a novel analogue of imipenem with significantly higher binding affinity and improved drug-likeness properties to overcome resistance of the pathogen and optimize bioavailability, respectively. De novo drug design was performed using virtual screening to predict the ligand(s) with the highest binding affinity. The two-dimensional and three-dimensional structure of the designed molecules were sketched using Chemdraw professional and MarvinSketch, respectively. After separating the targeted protein from A. baumannii PBP1A-imipenem complex structure (3UDX) and retaining a monomer (chain A) from a dimer of the protein structure using Text Editor (ConTEXT v0.98.6), docking was achieved using virtual screening AutoDock Vina program. Finally, drug-likeness properties were assessed. The results could find the selected compounds with significantly higher binding affinity and improved physicochemical properties compared with imipenem.

Acinetobacter baumannii (A. baumannii) is one of the major representative aetiologies of recalcitrant nosocomial infections. Genotypic and phenotypic alterations in A. baumannii have resulted in a significant surge in multidrug resistance (MDR). Of all the factors responsible for the development of antimicrobial resistance (AMR), efflux protein pumps play a paramount role. In pursuit of a safe alternative for the prevention and control of A. baumannii infections, bioactive compounds from the aerial parts of the medicinal plant Artemisia pallens were studied. GC-MS analysis of the ethanol extract of A. pallens detected five major compounds: lilac alcohol A, spathulenol, lilac alcohol C, n-hexadecanoic acid, and vulgarin. In silico examinations were performed using the Schrödinger suite. Homology modelling was performed to predict the structure of the efflux protein of A. baumannii-LAC-4 strain (MDR Ab-EP). The identified bioactive compounds were analysed for their binding efficiency with MDR Ab-EP. High binding efficiency was observed with vulgarin with a glide score of −4.775 kcal/mol and stereoisomers of lilac alcohol A (−3.706 kcal/mol) and lilac alcohol C (−3.706 kcal/mol). Our molecular dynamic simulation studies unveiled the stability of the ligand–efflux protein complex. Vulgarin and lilac alcohol A possessed strong and stable binding efficiency with MDR Ab-EP. Furthermore, validation of the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of the ligands strongly suggested that these compounds could serve as a lead molecule in the development of an alternate drug from A. pallens.

The aim of this work was to test polyamines as potential natural substrates of the Acinetobacter baumannii chlorhexidine efflux protein AceI using near-UV synchrotron radiation circular dichroism (SRCD) spectroscopy. The Gram-negative bacterium A. Baumannii is a leading cause of hospital-acquired infections and an important foodborne pathogen. A. Baumannii strains are becoming increasingly resistant to antimicrobial agents, including the synthetic antiseptic chlorhexidine. AceI (144-residues) was the founding member of the recently recognised PACE family of bacterial multidrug efflux proteins. Using the plasmid construct pTTQ18-aceI(His6) containing the A. baumannii aceI gene directly upstream from a His6-tag coding sequence, expression of AceI(His6) was amplified in E. coli BL21(DE3) cells. Near-UV (250–340 nm) SRCD measurements were performed on detergent-solubilised and purified AceI(His6) at 20 °C. Sample and SRCD experimental conditions were identified that detected binding of the triamine spermidine to AceI(His6). In a titration with spermidine (0–10 mM), this binding was saturable and fitting of the curve for the change in signal intensity produced an apparent binding affinity (KD) of 3.97 ± 0.45 mM. These SRCD results were the first experimental evidence obtained for polyamines as natural substrates of PACE proteins.

Therapeutic options including last-line or combined antibiotic therapies for multi-drug-resistant strains of Acinetobacter baumannii are ineffective. The outer membrane protein A (OmpA) and outer membrane protein W (OmpW) are two porins known for their different cellular functions. Identification of natural compounds with the potentials to block these putative porins can attenuate the growth of the bacteria and control the relating diseases. The current work aimed to screen a library of 384 phytochemicals according to their potentials to be used as a drug, and potentials to inhibit the function of OmpA and OmpW in A. baumannii . The phytocompounds were initially screened based on their physico-chemical, absorption, distribution, metabolism, excretion and toxicity (ADMET) drug-like properties. Afterwards, the selected ligands were subjected to standard docking calculations against the predicted three-dimensional structure of OmpA and OmpW in A. baumannii . We identified three phytochemicals (isosakuranetin, aloe-emodin and pinocembrin) possessing appreciable binding affinity towards the selected binding pocket of OmpA and OmpW. Molecular dynamics simulation analysis confirmed the stability of the complexes. Among them, isosakuranetin was suggested as the best phytocompound for further in vitro and in vivo study.

Fatty acid synthesis is essential for bacterial viability. Thus, fatty acid synthases (FASs) represent effective targets for antibiotics. Nevertheless, multidrug-resistant bacteria, including the human opportunistic bacteria, Acinetobacter baumannii, are emerging threats. Meanwhile, the FAS pathway of A. baumannii is relatively unexplored. Considering that acyl carrier protein (ACP) has an important role in the delivery of fatty acyl intermediates to other FAS enzymes, we elucidated the solution structure of A. baumannii ACP (AbACP) and, using NMR spectroscopy, investigated its interactions with β-ketoacyl ACP synthase III (AbKAS III), which initiates fatty acid elongation. The results show that AbACP comprises four helices, while Ca2+ reduces the electrostatic repulsion between acid residues, and the unconserved F47 plays a key role in thermal stability. Moreover, AbACP exhibits flexibility near the hydrophobic cavity entrance from D59 to T65, as well as in the α1α2 loop region. Further, F29 and A69 participate in slow exchanges, which may be related to shuttling of the growing acyl chain. Additionally, electrostatic interactions occur between the α2 and α3-helix of ACP and AbKAS III, while the hydrophobic interactions through the ACP α2-helix are seemingly important. Our study provides insights for development of potent antibiotics capable of inhibiting A. baumannii FAS protein–protein interactions.

Antibiotic resistance (AR) is the result of microbes’ natural evolution to withstand the action of antibiotics used against them. AR is rising to a high level across the globe, and novel resistant strains are emerging and spreading very fast. Acinetobacter baumannii is a multidrug resistant Gram-negative bacteria, responsible for causing severe nosocomial infections that are treated with several broad spectrum antibiotics: carbapenems, β-lactam, aminoglycosides, tetracycline, gentamicin, impanel, piperacillin, and amikacin. The A. baumannii genome is superplastic to acquire new resistant mechanisms and, as there is no vaccine in the development process for this pathogen, the situation is more worrisome. This study was conducted to identify protective antigens from the core genome of the pathogen. Genomic data of fully sequenced strains of A. baumannii were retrieved from the national center for biotechnological information (NCBI) database and subjected to various genomics, immunoinformatics, proteomics, and biophysical analyses to identify potential vaccine antigens against A. baumannii. By doing so, four outer membrane proteins were prioritized: TonB-dependent siderphore receptor, OmpA family protein, type IV pilus biogenesis stability protein, and OprD family outer membrane porin. Immuoinformatics predicted B-cell and T-cell epitopes from all four proteins. The antigenic epitopes were linked to design a multi-epitopes vaccine construct using GPGPG linkers and adjuvant cholera toxin B subunit to boost the immune responses. A 3D model of the vaccine construct was built, loop refined, and considered for extensive error examination. Disulfide engineering was performed for the stability of the vaccine construct. Blind docking of the vaccine was conducted with host MHC-I, MHC-II, and toll-like receptors 4 (TLR-4) molecules. Molecular dynamic simulation was carried out to understand the vaccine-receptors dynamics and binding stability, as well as to evaluate the presentation of epitopes to the host immune system. Binding energies estimation was achieved to understand intermolecular interaction energies and validate docking and simulation studies. The results suggested that the designed vaccine construct has high potential to induce protective host immune responses and can be a good vaccine candidate for experimental in vivo and in vitro studies.

The rise in the number of antibiotic-resistant bacteria has become a serious threat to health, making it important to identify, characterize and optimize new molecules to help us to overcome the infections they cause. It is well known that Acinetobacter baumannii has a significant capacity to evade the actions of antibacterial drugs, leading to its emergence as one of the bacteria responsible for hospital and community-acquired infections. Nonetheless, how this pathogen infects and survives inside the host cell is unclear. In this study, we analyze the time-resolved transcriptional profile changes observed in human epithelial HeLa cells after infection by A. baumannii, demonstrating how it survives in host cells and starts to replicate 4 h post infection. These findings were achieved by sequencing RNA to obtain a set of Differentially Expressed Genes (DEGs) to understand how bacteria alter the host cells’ environment for their own benefit. We also determine common features observed in this set of genes and identify the protein–protein networks that reveal highly-interacted proteins. The combination of these findings paves the way for the discovery of new antimicrobial candidates for the treatment of multidrug-resistant bacteria.

A. baumannii is an opportunistic pathogen and a major cause of various community-acquired infections. Strains of this species can be resistant to multiple antimicrobial agents, leaving limited therapeutic options, also lacking in methods for accurate and prompt diagnosis. In this context, AbTJ, a novel phage that infects A. baumannii MDR-TJ, was isolated and characterized, together with its two tail fiber proteins. Morphological analysis revealed that it belongs to Podoviridae family. Its host range, growth characteristics, stability under various conditions, and genomic sequence, were systematically investigated. Bioinformatic analysis showed that AbTJ consists of a circular, double-stranded 42670-bp DNA molecule which contains 62 putative open reading frames (ORFs). Genome comparison revealed that the phage AbTJ is related to the Acinetobacter phage Ab105-1phi (No. KT588074). Tail fiber protein (TFPs) gp52 and gp53 were then identified and confirmed as species-specific proteins. By using a combination of bioluminescent methods and magnetic beads, these TFPs exhibit excellent specificity to detect A. baumannii. The findings of this study can be used to help control opportunistic infections and to provide pathogen-binding modules for further construction of engineered bacteria of diagnosis and treatment.

ABSTRACTMultidrug-resistant Acinetobacter baumannii is regarded as a life-threatening pathogen mainly associated with nosocomial and community-acquired pneumonia. Here, we show that A. baumannii can bind the human carcinoembryonic antigen-related cell adhesion molecule (CEACAM) receptors CEACAM1, CEACAM5, and CEACAM6. This specific interaction enhances A. baumannii internalization in membrane-bound vacuoles, promptly decorated with Rab5, Rab7, and lipidated microtubule-associated protein light chain 3 (LC3). Dissecting intracellular signaling pathways revealed that infected pneumocytes trigger interleukin-8 (IL-8) secretion via the extracellular signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-κB) signaling pathways for A. baumannii clearance. However, in CEACAM1-L-expressing cells, IL-8 secretion lasts only 24 h, possibly due to an A. baumannii-dependent effect on the CEACAM1-L intracellular domain. Conversely, the glycosylphosphatidylinositol-anchored CEACAM5 and CEACAM6 activate the c-Jun NH2-terminal kinase (JNK)1/2-Rubicon-NOX2 pathway, suggestive of LC3-associated phagocytosis. Overall, our data show for the first time novel mechanisms of adhesion to and invasion of pneumocytes by A. baumannii via CEACAM-dependent signaling pathways that eventually lead to bacterial killing. These findings suggest that CEACAM upregulation could put patients at increased risk of lower respiratory tract infection by A. baumannii.IMPORTANCE This work shows for the first time that Acinetobacter baumannii binds to carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), CEACAM5, and CEACAM6. This binding significantly enhances A. baumannii internalization within alveolar host cell epithelia. Intracellular trafficking involves typical Rab5 and Rab7 vacuolar proteins as well as light chain 3 (LC3) and slowly progresses to bacterial killing by endosome acidification. CEACAM engagement by A. baumannii leads to distinct and specific downstream signaling pathways. The CEACAM1 pathway finely tunes interleukin-8 (IL-8) secretion, whereas CEACAM5 and CEACAM6 mediate LC3-associated phagocytosis. The present study provides new insights into A. baumannii-host interactions and could represent a promising therapeutic strategy to reduce pulmonary infections caused by this pathogen.

ABSTRACT It has been recently shown that resistance to both imipenem and meropenem in multidrug-resistant clinical strains of Acinetobacter baumannii is associated with the loss of a heat-modifiable 25/29-kDa outer membrane protein, called CarO. This study aimed to investigate the channel-forming properties of CarO. Mass spectrometry analyses of this protein band detected another 25-kDa protein (called Omp25), together with CarO. Both proteins presented similar physicochemical parameters (M w and pI). We overproduced and purified the two polypeptides as His-tagged recombinant proteins. Circular dichroism analyses demonstrated that the secondary structure of these proteins was mainly a β-strand conformation with spectra typical of porins. We studied the channel-forming properties of proteins by reconstitution into artificial lipid bilayers. In these conditions, CarO induced ion channels with a conductance value of 110 pS in 1 M KCl, whereas the Omp25 protein did not form any channels, despite its suggested porin function. The pores formed by CarO showed a slight cationic selectivity and no voltage closure. No specific imipenem binding site was found in CarO, and this protein would rather form unspecific monomeric channels.

Direct soaking of protein crystals with small-molecule fragments grouped into complementary clusters is a useful technique when assessing the potential of a new crystal system to support structure-guided drug discovery. It provides a robustness check prior to any extensive crystal screening, a double check for assay binding cutoffs and structural data for binding pockets that may or may not be picked out in assay measurements. The structural output from this technique for three novel fragment molecules identified to bind to the antibacterial target Acinetobacter baumannii undecaprenyl pyrophosphate synthase are reported, and the different physicochemical requirements of a successful antibiotic are compared with traditional medicines.

The remarkable rise in antimicrobial resistance is alarming for Acinetobacter baumannii, which necessitates effective strategies for the discovery of promising anti-acinetobacter agents. We used a subtractive proteomics approach to identify unique protein drug targets. Shortlisted targets passed through subtractive channels, including essentiality, non-homology to the human proteome, druggability, sub-cellular localization prediction and conservation. Sixty-eight drug targets were shortlisted; among these, glutamine synthetase, dihydrodipicolinate reductase, UDP-N-acetylglucosamine acyltransferase, aspartate 1-decarboxylase and bifunctional UDP-N-acetylglucosamine diphosphorylase/glucosamine-1-phosphate N-acetyltransferase were evaluated in vitro by determining the minimum inhibitory concentration (MIC) of candidate ligands, citric acid, dipicolinic acid, D-tartaric acid, malonic acid and 2-(N-morpholino)ethanesulfonic acid (MES), respectively, which ranged from 325 to 1500 μg/mL except for MES (25 mg/mL). The candidate ligands, citric acid, D-tartaric acid and malonic acid, showed good binding energy scores to their targets upon applying molecular docking, in addition to a significant reduction in A. baumannii microbial load in the wound infection mouse model. These ligands also exhibited good tolerability to human skin fibroblast. The significant increase in the MIC of malonic acid in β-alanine and pantothenate-supplemented media confirmed its selective inhibition to aspartate 1-decarboxylase. In conclusion, three out of sixty-eight potential A. baumannii drug targets were effectively inhibited in vitro and in vivo by promising ligands.

Antimicrobial peptides (AMPs) are alternative therapeutics to traditional antibiotics against bacterial resistance. Our previous work identified an antimicrobial region at the N-terminus of the eosinophil cationic protein (ECP). Following structure-based analysis, a 30mer peptide (ECPep-L) was designed that combines antimicrobial action against Gram-negative species with lipopolysaccharides (LPS) binding and endotoxin-neutralization activities. Next, analogues that contain non-natural amino acids were designed to increase serum stability. Here, two analogues were selected for in vivo assays: the all-D version (ECPep-D) and the Arg to Orn version that incorporates a D-amino acid at position 2 (ECPep-2D-Orn). The peptide analogues retained high LPS-binding and anti-endotoxin activities. The peptides efficacy was tested in a murine acute infection model of Acinetobacter baumannii. Results highlighted a survival rate above 70% following a 3-day supervision with a single administration of ECPep-D. Moreover, in both ECPep-D and ECPep-2D-Orn peptide-treated groups, clinical symptoms improved significantly and the tissue infection was reduced to equivalent levels to mice treated with colistin, used as a last resort in the clinics. Moreover, treatment drastically reduced serum levels of TNF-α inflammation marker within the first 8 h. The present results support ECP-derived peptides as alternative candidates for the treatment of acute infections caused by Gram-negative bacteria.

ABSTRACTAcinetobacter baumanniihas become a major problem in the clinical setting with the prevalence of infections caused by multidrug-resistant strains on the increase. Nevertheless, only a limited number of molecular mechanisms involved in the success ofA. baumanniias a human pathogen have been described. In this study, we examined the virulence features of a hypermotile derivative ofA. baumanniistrain ATCC 17978, which was found to display enhanced adherence to human pneumocytes and elevated levels of lethality towardCaenorhabditis elegansnematodes. Analysis of cellular lipids revealed modifications to the fatty acid composition, providing a possible explanation for the observed changes in hydrophobicity and subsequent alteration in adherence and motility. Comparison of the genome sequences of the hypermotile variant and parental strain revealed that an insertion sequence had disrupted anhns-like gene in the variant. This gene encodes a homologue of the histone-like nucleoid structuring (H-NS) protein, a known global transcriptional repressor. Transcriptome analysis identified the global effects of this mutation on gene expression, with major changes seen in the autotransporter Ata, a type VI secretion system, and a type I pilus cluster. Interestingly, isolation and analysis of a second independent hypermotile ATCC 17978 variant revealed a mutation to a residue within the DNA binding region of H-NS. Taken together, these mutants indicate that the phenotypic and transcriptomic differences seen are due to loss of regulatory control effected by H-NS.

Rational drug discovery strategy requires a design of small molecules as candidate drugs which can specifically inhibit a target protein or any other macromolecule and effectively interfere in a defined physiological process. One of the important bacterial protein targets aimed toward developing new antibiotics is peptidyl-tRNA hydrolase (Pth). The discovery that cytarabine, a known anticancer drug, binds to Pth from Acinetobacter baumannii in a cleft located away from the catalytic site of this enzyme, published in Biochemical Journal, opens up interesting new avenues for drug design. An approach involving crystallographic identification of multiple ligand-binding sites on a target protein surface could enable iterative optimization of multiple high-affinity ligands, which may synergistically interfere in the target function with enhanced effect.

Abstract Background LpxB is an enzyme involved in the biosynthesis pathway of lipid A, a component of LPS. Objectives To evaluate the lpxB gene in Acinetobacter baumannii as a potential therapeutic target and to propose antisense agents such as peptide nucleic acids (PNAs) as a tool to combat bacterial infection, either alone or in combination with known antimicrobial therapies. Methods RNA-seq analysis of the A. baumannii ATCC 17978 strain in a murine pneumonia model was performed to study the in vivo expression of lpxB. Protein expression was studied in the presence or absence of anti-lpxB (KFF)3K-PNA (pPNA). Time–kill curve analyses and protection assays of infected A549 cells were performed. The chequerboard technique was used to test for synergy between pPNA and colistin. A Galleria mellonella infection model was used to test the in vivo efficacy of pPNA. Results The lpxB gene was overexpressed during pneumonia. Treatment with a specific pPNA inhibited LpxB expression in vitro, decreased survival of the ATCC 17978 strain and increased the survival rate of infected A549 cells. Synergy was observed between pPNA and colistin in colistin-susceptible strains. In vivo assays confirmed that a combination treatment of anti-lpxB pPNA and colistin was more effective than colistin in monotherapy. Conclusions The lpxB gene is essential for A. baumannii survival. Anti-lpxB pPNA inhibits LpxB expression, causing bacterial death. This pPNA showed synergy with colistin and increased the survival rate in G. mellonella. The data suggest that antisense pPNA molecules blocking the lpxB gene could be used as antibacterial agents.

ABSTRACTGlutathione is a tripeptide (l-γ-glutamyl–l-cysteinyl–glycine) thiol compound existing in many bacteria and maintains a proper cellular redox state, thus protecting cells against toxic substances such as reactive oxygen species. Polyamines (spermine and spermidine) are low-molecular-weight aliphatic polycations ubiquitously presenting in all living cells and modulate many cellular functions. We previously reported that exogenous polyamines significantly enhanced β-lactam susceptibility of β-lactam-associated multidrug-resistantAcinetobacter baumannii. In this study, three genes differentially associated with the polyamine effects on β-lactam susceptibility were identified by transposon mutagenesis ofA. baumanniiATCC 19606. All three genes encoded components of membrane transport systems. Inactivation of one of the genes encoding a putative glutathione transport ATP-binding protein increased the accumulation of intracellular glutathione (∼150 to ∼200%) and significantly decreased the polyamine effects on β-lactam susceptibility inA. baumanniiATCC 19606. When the cells were grown with polyamines, the levels of intracellular glutathione inA. baumanniiATCC 19606 significantly decreased from ∼0.5 to ∼0.2 nmol, while the levels of extracellular glutathione were correspondingly increased. However, the levels of total glutathione (intra- plus extracellular) were unchanged when the cells were grown with or without polyamines. Overall, these results suggest that exogenous polyamines induce glutathione export, resulting in decreased levels of intracellular glutathione, which may produce an improper cellular redox state that is associated with the polyamine-mediated β-lactam susceptibility ofA. baumannii. This finding may provide a clue for development of new antimicrobial agents and/or novel strategies to treat multidrug-resistantA. baumannii.

ABSTRACTAlthoughAcinetobacter baumanniiis well accepted as a nosocomial pathogen, only a few of the outer membrane proteins (OMPs) have been functionally characterized. In this study, we demonstrate the biological functions of AbuO, a homolog of TolC fromEscherichia coli. Inactivation ofabuOled to increased sensitivity to high osmolarity and oxidative stress challenge. The ΔabuOmutant displayed increased susceptibility to antibiotics, such as amikacin, carbenicillin, ceftriaxone, meropenem, streptomycin, and tigecycline, and hospital-based disinfectants, such as benzalkonium chloride and chlorhexidine. The reverse transcription (RT)-PCR analysis indicated increased expression of efflux pumps (resistance nodulation cell division [RND] efflux pumpacrD, 8-fold; SMR-typeemrEhomolog, 12-fold; and major facilitator superfamily [MFS]-typeampGhomolog, 2.7-fold) and two-component response regulators (baeR, 4.67-fold;ompR, 10.43-fold) in the ΔabuOmutant together with downregulation ofrstA(4.22-fold) and the pilin chaperone (9-fold). The isogenic mutant displayed lower virulence in a nematode model (P< 0.01). Experimental evidence for the binding of MerR-type transcriptional regulator SoxR to radiolabeledabuOpromoter suggests regulation ofabuOby SoxR inA. baumannii.

Few antibiotics are effective againstAcinetobacter baumannii, one of the most successful pathogens responsible for hospital-acquired infections. Resistance to chlorhexidine, an antiseptic widely used to combatA. baumannii, is effected through the proteobacterial antimicrobial compound efflux (PACE) family. The prototype membrane protein of this family, AceI (Acinetobacterchlorhexidine efflux protein I), is encoded for by theaceIgene and is under the transcriptional control of AceR (Acinetobacterchlorhexidine efflux protein regulator), a LysR-type transcriptional regulator (LTTR) protein. Here we use native mass spectrometry to probe the response of AceI and AceR to chlorhexidine assault. Specifically, we show that AceI forms dimers at high pH, and that binding to chlorhexidine facilitates the functional form of the protein. Changes in the oligomerization of AceR to enable interaction between RNA polymerase and promoter DNA were also observed following chlorhexidine assault. Taken together, these results provide insight into the assembly of PACE family transporters and their regulation via LTTR proteins on drug recognition and suggest potential routes for intervention.

The Acinetobacter baumannii type strain, ATCC 19606, secretes acinetobactin, a catechol siderophore highly related to the iron chelator anguibactin produced by the fish pathogen Vibrio anguillarum (Listonella anguillarum). This paper reports the initial characterization of the genes and gene products involved in the acinetobactin-mediated iron-acquisition process. Insertional mutagenesis resulted in the isolation of several derivatives whose ability to grow in medium containing the iron chelator 2,2′-dipyridyl was affected. One of the insertions disrupted a gene encoding a predicted outer-membrane protein, named BauA, highly similar to FatA, the receptor for ferric anguibactin. Immunological relatedness of BauA with FatA was confirmed by Western blot analysis. Another transposon insertion was mapped to a gene encoding a protein highly similar to FatD, the permease component of the anguibactin transport system. Further DNA sequencing and nucleotide sequence analysis revealed that these A. baumannii 19606 genes are part of a polycistronic locus that contains the bauDCEBA ORFs. While the translation products of bauD, -C, -B and -A are highly related to the V. anguillarum FatDCBA iron-transport proteins, the product of bauE is related to the ATPase component of Gram-positive ATP-binding cassette (ABC) transport systems. This entire locus is flanked by genes encoding predicted proteins related to AngU and AngN, V. anguillarum proteins required for the biosynthesis of anguibactin. These protein similarities, as well as the structural similarity of anguibactin and acinetobactin, suggested that these two siderophores could be utilized by both bacterial strains, a possibility that was confirmed by siderophore utilization bioassays. Taken together, these results demonstrate that these pathogens, which cause serious infections in unrelated hosts, express very similar siderophore-mediated iron-acquisition systems.

Antimicrobial resistance is the key threat to global health due to high morbidity and mortality. The alteration of bacterial proteins, enzymatic degradation, and change of membrane permeability towards antimicrobial agents are the key mechanisms of antimicrobial resistance. Based on the current condition, there is an urgent clinical need to develop new drugs to treat these bacterial infections. In the current study, the binding patterns of selected antimicrobial peptides (AMPs) with different multidrug-resistant bacterial strains have been analyzed. Among ten selected AMPs in this study, napin and snakin-1 exhibited the best scores and binding patterns. Napin exhibited strong interactions with penicillin-binding protein 1a of Acinetobacter baumannii (with a binding score of -158.7 kcal/mol and ten hydrogen bonds), with glucose-1-phosphate thymidylyltransferase of Mycobacterium tuberculosis H37Rv (with a binding score of -107.8 kcal/mol and twelve hydrogen bonds), and with streptomycin 3 ″ -adenylyltransferase protein of Salmonella enterica (with a binding score of -84.2 kcal/mol and four hydrogen bonds). Similarly, snakin-1 showed strong interactions with oxygen-insensitive NADPH nitroreductase of Helicobacter pylori (with a binding score of -105.0 kcal/mol and thirteen hydrogen bonds) and with penicillin-binding protein 2a of methicillin-resistant Staphylococcus aureus (with a binding score of -103.8 kcal/mol and twenty-three hydrogen bonds). The docking results were further validated by molecular dynamics simulations. The results of this computational approach support the evidence of efficiency of these AMPs as potent inhibitors of these specific proteins of bacterial strains. However, further validations are required to fully evaluate the potential of selected AMPs as drug candidates against these resistant bacterial strains.

OXA-239 is a class D carbapenemase isolated from an Acinetobacter baumannii strain found in Mexico. This enzyme is a variant of OXA-23 with three amino acid substitutions in or near the active site. These substitutions cause OXA-239 to hydrolyze late-generation cephalosporins and the monobactam aztreonam with greater efficiency than OXA-23. OXA-239 activity against the carbapenems doripenem and imipenem is reduced ∼3-fold and 20-fold, respectively. Further analysis demonstrated that two of the substitutions (P225S and D222N) are largely responsible for the observed alteration of kinetic parameters, while the third (S109L) may serve to stabilize the protein. Structures of OXA-239 with cefotaxime, doripenem and imipenem bound as acyl-intermediates were determined. These structures reveal that OXA-239 has increased flexibility in a loop that contains P225S and D222N. When carbapenems are bound, the conformation of this loop is essentially identical with that observed previously for OXA-23, with a narrow active site that makes extensive contacts to the ligand. When cefotaxime is bound, the loop can adopt a different conformation that widens the active site to allow binding of that bulky drug. This alternate conformation is made possible by P225S and further stabilized by D222N. Taken together, these results suggest that the three substitutions were selected to expand the substrate specificity profile of OXA-23 to cephalosporins and monobactams. The loss of activity against imipenem, however, suggests that there may be limits to the plasticity of class D enzymes with regard to evolving active sites that can effectively bind multiple classes of β-lactam drugs.

Abstract Background Multidrug-resistant (MDR) A. baumannii presents a critical need for innovative antibacterial development. We have identified a new series of γ-lactam (oxopyrazole) antibiotics that target penicillin binding proteins (PBPs) and incorporate a siderophore moiety to facilitate periplasmic uptake. YU253911, an advanced iteration of this class shows potent in vitro activity against clinically relevant Gram-negative organisms including Acinetobacter spp. Methods Minimum inhibitory concentrations (MICs) for YU253911 were determined using broth microdilution against a 198-member panel of clinical isolates of Acinetobacter spp. Resistant strains were further evaluated for susceptibility to YU253911 in combination with sulbactam. The antibiotic’s target protein was evaluated by binding studies with Bocillin™, a fluorescent penicillin analogue, and modeled in the PBP active site. YU253911 was evaluated in vivo in a mouse soft tissue infection model. Results MIC testing for YU253911 revealed an MIC50 of 0.5 μg/mL and an MIC90 of 16 μg/mL, which compared favorably to all tested β-lactam antibiotics including penicillins, cephalosporins, monobactams and carbapenems (MIC50 = 2 to &gt; 16 μg/mL). Combination with sulbactam augmented the activity of the agent. There was no apparent correlation between YU253911-resistance and the presence of specific β-lactamase genes, and incubation with representative β-lactamase proteins (KPC-2, OXA-23, OXA-24, PER-2, PDC-3, NDM-1, VIM-2, and IMP-1) showed negligible hydrolysis of the agent. YU253911 showed promising preclinical pharmacokinetics in mice with a 15 h half-life from intravenous administration and demonstrated a dose-dependent reduction in colony forming units from 50 and 100 mg/kg q6h dosing in a mouse thigh infection model using P. aeruginosa. Conclusion YU253911, a new generation γ-lactam antibiotic effective against MDR A. baumannii demonstrated promising in in vitro potency and favorable pharmacokinetics which correlated with in vivo efficacy. Disclosures Krisztina M. Papp-Wallce, PhD, Entasis (Grant/Research Support)Merck (Grant/Research Support)Venatorx (Grant/Research Support) Robert A. Bonomo, MD, Entasis, Merck, Venatorx (Research Grant or Support)

In this work, the antibacterial activity of deflazacort and several of its synthetic precursors was tested against a panel of bacterial pathogens responsible for most drug-resistant infections including Staphylococcus aureus, Enterococcus spp., Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. The derivative of deflazacort, PYED-1 (pregnadiene-11-hydroxy-16α,17α-epoxy-3,20-dione-1) showed the best antibacterial activity in a dose-dependent way. We focused on the action of PYED-1 against S. aureus cells. PYED-1 exhibited an additive antimicrobial effect with gentamicin and oxacillin against the methicillin-resistant S. aureus isolate 00717. In addition to its antimicrobial effect, PYED-1 was found to repress the expression of several virulence factors of S. aureus, including toxins encoded by the hla (alpha-haemolysin), hlb (beta-haemolysin), lukE-D (leucotoxins E-D), and sea (staphylococcal enterotoxin A) genes, and cell surface factors (fnbB (fibronectin-binding protein B) and capC (capsule biosynthesis protein C)). The expression levels of autolysin isaA (immunodominant staphylococcal antigen) were also increased.

Abstract Background Cefiderocol (CFDC) is a novel siderophore cephalosporin with efficacy against Gram-negative (GN) bacteria, including carbapenem-resistant Enterobacterales and non-glucose-fermenters such as Pseudomonas aeruginosa and Acinetobacter baumannii. In consecutive multinational surveillance (SIDERO-WT) studies (2014–2017), CFDC demonstrated activity with minimum inhibitory concentrations (MICs) of ≤4 mg/mL against 99.4% of 28,629 GN clinical isolates. We conducted molecular characterization of 161 isolates with CFDC MICs &gt;4 mg/mL from the SIDERO-WT studies. Methods A total of 161 isolates underwent whole genome sequencing by Illumina Hiseq. Analyses were done using the CLC genomics workbench (Qiagen) for possible resistance-related genes (e.g. β-lactamases, porin channels or penicillin-binding protein genes) and some TonB-dependent siderophore uptake receptor genes (fiu, cir, piu, pir). Fiu and Cir in Escherichia coli and Piu in P. aeruginosa are the iron transporters involved in CFDC transport. Results Of 161 isolates with CFDC MIC &gt;4 mg/mL, 128 were A. baumannii, 22 Enterobacterales, 7 Burkholderia multivorans, 2 P. aeruginosa, and 2 Stenotrophomonas maltophilia. Genes encoding PER/VEB extended-spectrum β-lactamases and NDM-type metallo-β-lactamases were detected in some isolates, but other β-lactamase genes (bla) were not shown to be linked to high CFDC MICs. blaPER/blaVEB were found only in A. baumannii and blaNDM was found in A. baumannii and Klebsiella pneumoniae. In 128 A. baumannii isolates, 103 harbored PER or VEB, including PER positive isolates from Russia (n=87) and Turkey (n=6) and 4 VEB positive isolates from USA. Nine NDM-positive isolates (7 K. pneumoniae, 2 A. baumannii) were found. Disruption of iron transport genes was also detected in some isolates, including piuA (11 A. baumannii, 1 P. aeruginosa), pirA (2 A. baumannii), and fiuA (4 B. multivorans, 1 Proteus mirabilis). No cir homologs were found in 2 B. multivorans. Conclusion PER and NDM could reduce susceptibility to CFDC, as such isolates have been seen in some countries. Iron transporter disruption was also observed in some isolates with high CFDC MICs; the contribution of these deficiencies in A. baumannii and B. multivorans requires further study. Disclosures Yoshinori Yamano, PhD, Shionogi & Co., Ltd. (Employee) Miki Takemura, MSc, Shionogi & Co., Ltd. (Employee) Krystyna Kazmierczak, PhD, Shionogi & Co., Ltd. (Independent Contractor) Mark G G. Wise, PhD, Shionogi & Co., Ltd. (Independent Contractor) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Consultant)Shionogi & Co., Ltd. (Independent Contractor) Roger Echols, MD, Shionogi Inc. (Consultant)

Antibiotics at suboptimal doses promote biofilm formation and the development of antibiotic resistance. The underlying molecular mechanisms, however, were not investigated. Here, we report the effects of sub-minimum inhibitory concentrations (sub-MICs) of imipenem and colistin on genes associated with biofilm formation and biofilm-specific antibiotic resistance in a multidrug-tolerant clinical strain of Acinetobacter baumannii Sequence Type (ST) 1894. Comparative transcriptome analysis was performed in untreated biofilm and biofilm treated with sub-MIC doses of imipenem and colistin. RNA sequencing data showed that 78 and 285 genes were differentially expressed in imipenem and colistin-treated biofilm cells, respectively. Among the differentially expressed genes (DEGs), 48 and 197 genes were upregulated exclusively in imipenem and colistin-treated biofilm cells, respectively. The upregulated genes included those encoding matrix synthesis (pgaB), multidrug efflux pump (novel00738), fimbrial proteins, and homoserine lactone synthase (AbaI). Upregulation of biofilm-associated genes might enhance biofilm formation when treated with sub-MICs of antibiotics. The downregulated genes include those encoding DNA gyrase (novel00171), 30S ribosomal protein S20 (novel00584), and ribosome releasing factor (RRF) were downregulated when the biofilm cells were treated with imipenem and colistin. Downregulation of these genes affects protein synthesis, which in turn slows down cell metabolism and makes biofilm cells more tolerant to antibiotics. In this investigation, we also found that 5 of 138 small RNAs (sRNAs) were differentially expressed in biofilm regardless of antibiotic treatment or not. Of these, sRNA00203 showed the highest expression levels in biofilm. sRNAs regulate gene expression and are associated with biofilm formation, which may in turn affect the expression of biofilm-specific antibiotic resistance. In summary, when biofilm cells were exposed to sub-MIC doses of colistin and imipenem, coordinated gene responses result in increased biofilm production, multidrug efflux pump expression, and the slowdown of metabolism, which leads to drug tolerance in biofilm. Targeting antibiotic-induced or repressed biofilm-specific genes represents a new strategy for the development of innovative and effective treatments for biofilm-associated infections caused by A. baumannii.

Eksplorasi enzim secara tradisional dengan kultivasi mikroba sekarang ini tidak lagi efisien, karena menghabiskan waktu dan biaya. Bioinformatik berbasis web hadir untuk melakukan serangkaian analisis sekuen, baik itu DNA maupun protein, yang dapat digunakan sebagai penelitian pendahuluan, sehingga ekplorasi enzim menjadi lebih tepat sasaran. Penelitian ini telah melakukan analisis potongan sekuen 16S ribosomal RNA yang didapat dari 6 bakteri yang berasosiasi dengan udang. Analisis yang dilakukan adalah untuk mencari tahu tersedianya sekuen tersebut telah ada di <em>Gene Bank</em> atau merupakan strain baru khas Indonesia yang belum terpublikasi. Dengan menggunakan <em>database</em> <em>16S Microbial</em> dan <em>Reference Genomic Sequence</em>, serta fasilitas BLAST nucleotide dan CLUSTALW2 didapatkan 5 nama bakteri yaitu <em>Micromonospora</em> sp. L5, <em>Aeromonas veronii</em> B565, <em>Staphylococcus epidermidis</em> ATCC 12228, <em>Burkholderia </em>sp. JV3, dan <em>Acinetobacter baumannii</em>AB307-0294. Kelima mikroba ini memiliki tidak mempunyai gen kitosanase tetapi penyandi kitinase. Ketidakhadiran gen kitosanase dalam genome mikroba menjadikan mikroba unik untuk diketahui sekuens gen kitosanasenya, yang juga berpeluang untuk dipublikasikan.<p style="text-align: center;"><strong>Abstract</strong></p><p style="text-align: justify;"><em></em>Enzymes exploration which is traditionally conducted by microbial cultivation, is no longer efficient, for spending the time and cost. Web based bioinformatics presents to do a series of sequence analysis, for query both DNA and protein, which can be used as preliminary test in order to direct the research effectively. We have conducted an analysis of 16S ribosomal RNA sequences from 6 bacteria in association with shrimp. The goal is finding out the recording in <em>Gene Bank</em>s, which if they have not recorded means they are Indonesian strain. Using the 16S Microbial and Reference Genomic Sequence <em>database</em>s, as well as BLAST nucleotide and CLUSTALW2, we obtained 5 names of bacteria, i.e., <em>Micromonospora</em> sp. L5, <em>Aeromonas veronii</em> B565, <em>Staphylococcus epidermidis</em> ATCC 12228, <em>Burkholderia </em>sp. JV3, and <em>Acinetobacter baumannii </em>AB307-0294. These microbes do not have the chitosanase gene but have chitinase gene. The absence of chitosanase gene is unique its sequence that also gives opportunity for publication.</p>

Objective: Wound dressings that inactivate or sequestrate microorganisms, such as those with a hydrophobic, bacteria-binding dialkylcarbamoyl chloride (DACC) surface, can reduce the risk of clinical infections. This ‘passive’ bioburden control, avoiding bacterial cell wall disruption with associated release of bacterial endotoxins aggravating inflammation, is advantageous in hard-to-heal wounds. Hence, the full scope of DACC dressings, including the potential impact of higher inoculum densities, increased protein load and different pH on antibacterial activity, needs to be evaluated. Method: The Japanese Industrial Standard (JIS) L 1902 challenge test was used to evaluate the antimicrobial activity of the DACC-coated dressing against several World Health Organization (WHO)-prioritised wound pathogens (e.g., meticillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, microorganisms with extended-spectrum beta-lactamases and Acinetobacter baumannii), the effect of repeated bacterial challenge in an adverse wound environment, and antimicrobial performance at wound-related pH. Results: High antibacterial activity of the DACC-coated dressing against the WHO-prioritised bacteria strains by its irreversible binding and inhibition of growth of bound bacteria was confirmed using JIS L 1902. At increased inoculation densities, compared to standard conditions, the DACC-coated dressing still achieved strong-to-significant antibacterial effects. Augmenting the media protein content also affected antibacterial performance; a 0.5–1 log reduction in antibacterial activity was observed upon addition of 10% fetal calf serum. The pH did not influence antibacterial performance. The DACC-coated dressing also sustained antibacterial activity over subsequent reinfection steps. Conclusion: It can be assumed that the DACC-coated dressing exerts beneficial effects in controlling the wound bioburden, reducing the overall demand placed on antibiotics, without using antimicrobial substances.

The metal(II) complexes were synthesized by addition of corresponding MCl2 (M = Mn2+, Ni2+, Cu2+ and Zn2+) with 1,2-bis(1H-pyrrol-2-ylmethylene)diazane in methanol. The ligand acts as a bidentate as confirmed from the mass, IR, UV, NMR and EPR spectral studies. The Schiff base ligand forms hexa-coordinated complexes having octahedral geometry for Mn(II), Ni(II), Zn(II) and Cu(II) complexes. The metal complexes showed an excellent antimicrobial activity spectrum in vitro against both Gram-negative (Klebsiella pneumoniae and Acinetobacter baumannii), Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and human pathogenic bacteria isolates. To find the binding affinity with protein BSA kinase, for that molecular docking studies were also carried for all the four synthesized metal(II) complexes. The anticancer activity of the synthesized metal(II) complexes was also screened against the three human tumor cell lines MCF7 human breast adenocarcinoma cell line, CaSki human caucasian cervical epidermoid carcinoma and HCT116 human colon cancer cell lines. The present study showed that Zn(II) complex showed potent inhibition by the ratio of 80% as compared to the inhibition in the normal cells (L-6).

ABSTRACTClass C cephalosporinases are a growing threat, and inhibitors of these enzymes are currently unavailable. Studies exploring the YXN loop asparagine in theEscherichia coliAmpC, P99, and CMY-2 enzymes have suggested that interactions between C6′ or C7′ substituents on penicillins or cephalosporins and this Asn are important in determining substrate specificity and enzymatic stability. We sought to characterize the YXN loop asparagine in the clinically important ADC-7 class C β-lactamase ofAcinetobacter baumannii. Mutagenesis at the N148 position in ADC-7 yields functional mutants (N152G, -S, -T, -Q, -A, and -C) that retain cephalosporinase activity. Using standard assays, we show that N148G, -S, and -T variants possess good catalytic activity toward cefoxitin and ceftaroline but that cefepime is a poor substrate. Because N152 variants of CMY-2, another class C β-lactamase, are more readily inhibited by tazobactam due to higher rates of inactivation, we also tested if the N148 substitutions in ADC-7 would affect inactivation by sulfone inhibitors, sulbactam and tazobactam, class A β-lactamase, andA. baumanniipenicillin-binding protein (PBP) inhibitors within vitroactivity against ADC-7. The 50% inhibitory concentrations (IC50s) for tazobactam and sulbactam were improved, with 7-fold and 2-fold reductions, respectively, for the N148S variant. A homology model of the N148S ADC-7 enzyme in a Michaelis-Menten complex with tazobactam showed a loss of interaction between N148 and the sulfone moiety of the inhibitor. We postulate that this may result in more-rapid secondary ring opening of the inhibitor, as the unbound sulfone is an excellent leaving group, leading to more-rapid formation of the stable linearized inhibitor.

Antimicrobial resistance is among the top global health problems with antibacterial resistance currently representing the major threat both in terms of occurrence and complexity. One reason current treatments of bacterial diseases are ineffective is the occurrence of protective and resistant biofilm structures. Phytochemicals are currently being reviewed for newer anti-virulence agents. In the present study, we aimed to investigate the anti-virulence activity of 3,3′-diindolylmethane (DIM), a bioactive cruciferous phytochemical. Using a series of in vitro assays on major Gram-negative pathogens, including transcriptomic analysis, and in vivo porcine wound studies as well as in silico experiments, we show that DIM has anti-biofilm activity. Following DIM treatment, our findings show that biofilm formation of two of the most prioritized bacterial pathogens Acinetobacter baumannii and Pseudomonas aeruginosa was inhibited respectively by 65% and 70%. Combining the antibiotic tobramycin with DIM enabled a high inhibition (94%) of P. aeruginosa biofilm. A DIM-based formulation, evaluated for its wound-healing efficacy on P. aeruginosa-infected wounds, showed a reduction in its bacterial bioburden, and wound size. RNA-seq was used to evaluate the molecular mechanism underlying the bacterial response to DIM. The gene expression profile encompassed shifts in virulence and biofilm-associated genes. A network regulation analysis showed the downregulation of 14 virulence-associated super-regulators. Quantitative real-time PCR verified and supported the transcriptomic results. Molecular docking and interaction profiling indicate that DIM can be accommodated in the autoinducer- or DNA-binding pockets of the virulence regulators making multiple non-covalent interactions with the key residues that are involved in ligand binding. DIM treatment prevented biofilm formation and destroyed existing biofilm without affecting microbial death rates. This study provides evidence for bacterial virulence attenuation by DIM.

Background: Cefiderocol is a novel parenteral siderophore cephalosporin, demonstrating enhanced activity against multidrug-resistant (MDR) Gram-negative bacteria and difficult-to-treat Acinetobacter baumannii (DTR-AB). Plasma-free trough concentration (fCtrough) over the minimum inhibitory concentration (MIC) was reported as the best pharmacokinetic parameter to describe the microbiological efficacy of cefiderocol. Materials and methods: We retrospectively described the pharmacokinetic and pharmacodynamic profile of three critically ill patients admitted to the intensive care unit, receiving cefiderocol under compassionate use to treat severe DTR-AB infections while undergoing continuous venovenous haemofiltration. Cefiderocol was administrated at a dosage of 2 g every 8 h infused over 3 h. Therapeutic drug monitoring (TDM) was assessed at the steady state. Cthrough was evaluated by assuming a plasma protein binding of 58.0%. The fCmin/MIC was calculated assuming a cefiderocol MIC equal to the PK-PD breakpoint of susceptibility ≤ 2. The association between the PK/PD parameters and microbiological outcome was assessed. Results: fCtrough/MIC were >12 in 2 patients and 2.9 in the 1 who rapidly recovered from renal failure. Microbiological cure occurred in 3/3 of patients. None of the 3 patients died within 30 days. Conclusions: A cefiderocol dosage of 2 g q8 h in critically ill patients with AKI undergoing CVVH may bring about a very high plasma concentration, corresponding to essentially 100% free time over the MIC for DTR-AB.

Background: Gram-negative bacterial infections are on the rise due to the high prevalence of multidrug-resistant bacteria, and efforts must be made to identify novel drug targets and then new antibiotics. Methods: In the upstream part, we retrieved the genome sequences of 4 highly resistant Gram-negative bacteria (e.g., Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter cloacae). The core proteins were assessed to find common, cytoplasmic, and essential proteins with no similarity to the human proteome. Novel drug targets were identified using DrugBank, and their sequence conservancy was evaluated. Protein Data Bank files and STRING interaction networks were assessed. Finally, the aminoacylation cavity of glycyl-tRNA synthetase (GlyQ) was virtually screened to identify novel inhibitors using AutoDock Vina and the StreptomeDB library. Ligands with high binding affinity were clustered, and then the pharmacokinetics properties of therapeutic agents were investigated. Results: A total of 6 common proteins (e.g., RP-L28, RP-L30, RP-S20, RP-S21, Rnt, and GlyQ) were selected as novel and widespread drug targets against highly resistant Gram-negative superbugs based on different criteria. In the downstream analysis, virtual screening revealed that Rimocidin, Flavofungin, Chaxamycin, 11,11′-O-dimethyl-14′-deethyl-14′-methylelaiophylin, and Platensimycin were promising hit compounds against GlyQ protein. Finally, 11,11′-O-dimethyl-14′-deethyl-14′-methylelaiophylin was identified as the best potential inhibitor of GlyQ protein. This compound showed high absorption capacity in the human intestine. Conclusion: The results of this study provide 6 common putative new drug targets against 4 highly resistant and Gram-negative bacteria. Moreover, we presented 5 different hit compounds against GlyQ protein as a novel therapeutic target. However, further in vitro and in vivo studies are needed to explore the bactericidal effects of proposed hit compounds against these superbugs.

The antimicrobial properties of proline-rich Aedes aegypti decapeptide TMOF (AeaTMOF) and oncocin112 (1–13) were compared. Incubations with multidrug-resistant Escherichia coli cells showed that AeaTMOF (5 mM) was able to completely inhibit bacterial cell growth, whereas oncocin112 (1–13) (20 mM) partially inhibited bacterial growth as compared with bacterial cells that were not multidrug-resistant cells. AeaTMOF (5 mM) was very effective against Acinetobacter baumannii and Pseudomonas aeruginosa, completely inhibiting cell growth during 15 h incubations. AeaTMOF (5 mM) completely inhibited the Gram-positive bacteria Staphylococcus aureus and Bacillus thurengiensis sups. Israelensis cell growth, whereas oncocin112 (1–13) (10 and 20 mM) failed to affect bacterial cell growth. E. coli cells that lack the SbmA transporter were inhibited by AeaTMOF (5 mM) and not by oncocin112 (1–13) (10 to 20 mM), indicating that AeaTMOF can use other bacterial transporters than SbmA that is mainly used by proline-rich antimicrobial peptides. Incubation of E. coli cells with NaAzide showed that AeaTMOF does not use ABC-like transporters that use ATP hydrolysis to import molecules into bacterial cells. Three-dimensional modeling and docking of AeaTMOF to SbmA and MdtM transporters showed that AeaTMOF can bind these proteins, and the binding location of AeaTMOF inside these protein transporters allows AeaTMOF to be transported into the bacterial cytosol. These results show that AeaTMOF can be used as a future antibacterial agent against both multidrug-resistant Gram-positive and -negative bacteria.

AbstractCefiderocol, a novel parenteral siderophore cephalosporin, exhibits potent in vitro activity and in vivo efficacy against most gram-negative bacteria, including carbapenem-resistant strains of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia. In phase 1 studies, cefiderocol demonstrated linear pharmacokinetics, primarily urinary excretion, an elimination half-life of 2–3 hours, and a protein binding of 58% in human plasma. Cefiderocol is a time-dependent cephalosporin; the probability of a target attainment at ≥75% of the dosing interval during which the free drug concentration exceeds the minimum inhibitory concentration (ƒT/MIC) for bacterial strains with an MIC of ≤4 μg/mL is likely to be achieved at the therapeutic dose of 2 g over 3-hour infusion every 8 hours in most patients. As expected, renal function markers were the most influential covariates for the pharmacokinetics of cefiderocol for patients with renal impairment or augmented renal clearance (ARC). Dose adjustment is recommended for patients with impaired renal function, and additionally, in ARC patients with creatinine clearance >120 mL/minute, a more frequent dosing regimen (ie, 2 g every 6 hours) was predicted to achieve the target fT > MIC. The single and multiple doses of cefiderocol tested were well tolerated in both healthy subjects and those with renal impairment. Furthermore, neither QT interval prolongation nor drug–drug interaction via organic anion transporters was demonstrated in healthy subjects. Cefiderocol is being investigated in phase 3 clinical studies for the treatment of infections caused by carbapenem-resistant bacteria.

Antimicrobial peptides (AMPs) of neutrophils play an important role in the animal and human host defenses. We have isolated two AMPs (average molecular masses of 2895.5 and 2739.3 Da), with potent antimicrobial activity from neutrophils of the domestic goat (Capra hircus). A structural analysis of the obtained peptides revealed that they encompass N-terminal fragments (1-21 and 1-22) of the proline-rich peptide bactenecin 7.5. The primary structure of caprine bactenecin 7.5 had been previously deduced from the nucleotide sequence, but the corresponding protein had not been isolated from leukocytes until now. The obtained caprine AMPs were designated as mini-batenecins (mini-ChBac7.5N and mini-ChBac7.5N), analogously to the reported C-terminal fragment of the ovine bactenecin 7.5 named Bac7.5mini [Anderson, Yu, 2003]. Caprine mini-ChBac7.5N and mini-ChBac7.5N exhibit significant antimicrobial activity against Gram-negative bacteria, including drug-resistant strains of Pseudomonas aeruginosa, Klebsiella spp., Acinetobacter baumannii at a range of concentrations of 0.5-4 M, as well as against some species of Gram-positive bacteria (Listeria monocytogenes EGD, Micrococcus luteus). The eptides demonstrate lipopolysaccharide-binding activity. Similarly to most proline-rich AMPs, caprine peptides inactivate bacteria without appreciable damage of their membranes. Mini-ChBac7.5N and mini-ChBac7.5N have no hemolytic effect on human red blood cells and are nontoxic to various cultured human cells. Therefore, they might be considered as promising templates for the development of novel antibiotic pharmaceuticals. Isolation of highly active fragments of the antimicrobial peptide from goat neutrophils supports the hypothesis that fragmentation of cathelicidin-related AMPs is an important process that results in the generation of potent effector molecules, which are in some cases more active than full-size AMPs. These truncated AMPs may play a crucial role in host defense reactions.

Abstract Background A translational murine model of thigh infection with comorbid iron overload was previously developed to study the efficacy of iron-dependent siderophore-antibiotic conjugates under conditions where the hypoferremic response of innate immunity may be compromised. Given the potential for functional organ damage from excessive tissue iron, which could alter the pharmacokinetic (PK) profiles of antibiotics being compared for efficacy using this model, the effects of iron overload on a siderophore-β-lactam conjugate, cefiderocol (CFDC), and a non-siderophore β-lactam, meropenem (MEM), were studied. Methods Female CD-1 mice received iron dextran (Fe-D) 100 mg/kg intraperitoneally for 14 days as previously shown to produce vastly supranormal iron concentrations in serum, liver, and spleen (ASM Microbe 2019 abstract HMB-373). Age-matched control mice were not dosed with Fe-D. Mice were rendered neutropenic. On day 15, both thighs of iron-overloaded and control mice were inoculated intramuscularly with Acinetobacter baumannii suspensions of 107 CFU/mL. Two hours after inoculation, mice in each model were dosed with previously developed human-simulated regimens (HSR) of CFDC or MEM simulating human PK profiles after doses of 2g q8h (3 hours infusion) for both drugs. At 4 time points per regimen, 6 mice per model were sacrificed for blood collection. Plasma total MEM and CFDC concentrations were measured with HPLC and LC-MS-MS, respectively. Free concentrations were calculated with murine protein binding. At each time point, mean free concentrations in both models were compared using Student’s t-test. Results Observed murine-free plasma concentrations ± 95% CI of CFDC and MEM are overlaid with simulated human and murine profiles in the figure. In both models, these regimens approximated human exposures after clinical doses. For all time points and both drugs, concentrations were not significantly different (P > 0.05) between models with or without iron overload. Conclusion Iron overload did not significantly alter PK profiles of a siderophore-β-lactam conjugate, CFDC, or a non-siderophore β-lactam, MEM. These data support the use of CFDC and MEM HSR for pharmacodynamic studies utilizing both iron-overloaded and standard murine thigh infection models. Disclosures All authors: No reported disclosures.

Green gram (Vigna radiata) is considered the chief legume in Pakistan. Thus, current study was conducted to examine the ameliorating effect of phytohormones pre-treatments under salt stress on proteome profile of green gram by sodium-dodecyl-sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The soluble green gram seedlings proteins were resolved on 4% stacking and 12% resolving gels. The SDS-PAGE resolved 24 polypeptide bands ranging from 200 to 17kDa. Among these, 12 out of 24 bands of proteins were essentials house-keeping or growth proteins of green grams. While, 120, 114.6, 51.8, 29.1, and 22.8 kDa bands were over-expressed under 50 to 350mM salt with phytohormones treatments. The others 104.5 kDa, 99.8 kDa, 95.3 kDa, 91.0 kDa, 55 kDa, 46 kDa, and 17kDa bands were related to the GAᴣ, IAA, and SA induced tolerance. Overall 120 kDa, 114.6 kDa, 104.5 kDa, 99.8, 95.3 kDa, 51.8 kDa, 29.1 kDa and 22.8kDa bands were first time identified in the current study. The information retrieved from NCBI protein database, the resolved peptides were principally belonging to 7S and 8S vicilin, 2S, 8S, 11S, and 16.5S globulins. It is determined that seed priming with SA enhanced tolerance in green gram by rapidly synthesizing stress alleviating peptides.Key word: Cluster analysis, dendrogram, mungbean, salt stress, SDS-PAGEINTRODUCTIONVarious world-wide health concerning organization recommended the use of high graded plant protein such as legumes to prevent the risk of metabolic disorder (Hou et al., 2019). Legumes are most important protein crop on the earth. Among the legumes, the green gram is the major pulses. Its seeds are rich in superior quality storage protein, which account 85% of the total protein while, another 15% have not been broadly studied (Yi-Shen et al., 2018). The soluble storage protein comprises of 60% globulins, 25% albumin and 15% prolamins. Globulins are further divided into 3.4% basic-type (7S), 7.6% legumin-type (11S), and 89% vicilin-type (8S) (Mendoza et al., 2001; Itoh et al., 2006). Other than proteins, the green gram seeds also contain starch, fiber, phenolic compound, saponins, vitamins, calcium zinc, potassium, folate, magnesium, manganese and very low in fat that made it meager man’s meat (Hou et al., 2019). It is also a good source of green manure and fodder (El-Kafafi et al., 2015). Its root has ability to fix 30 to 50 Kg/ha atmospheric nitrogen in the soil which is essential for maintaining soil fertility (Chadha, 2010). The green gram is the valuable and the major Rabi pulse crop of Pakistan. Its cultivation area in 2016-2017 was about 179,000 hectares with seed yield of 130,000 tones. In comparison during 2017-2018, it was cultivated on 161,800 hectares land with 118,800 tones seed yield (GOP, 2018). One of the reasons of this 9% decrease in both land and productivity is the shortage of irrigated land due to soil salinity. The salinity induce oxidative bust in the mungbean cells, caused by responsive oxygen species (ROS) such as hydrogen peroxide, singlet oxygen, hydroxyl radical and superoxide radical. The ROS create hindrance in various metabolic processes of plant via interacting with macromolecules like proteins (Alharby et al., 2016). However, phytohormones like gibberellic acid (GAᴣ), indole acetic acid (IAA), and salicylic acid (SA) take part in the biosynthesis of salt tolerance proteins under salinity. These salt tolerance proteins acclimate plants under salinity stress. Application of biotechnology plays a significant role in agriculture (Khan et al., 2017). Therefore, production of particular proteins under salt stress is a specific response of cell which can be analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). SDS-PAGE is the simple, valid, and cost-effective biochemical marker (Mushtaq et al., 2018). This marker has been widely used to determine the extent of evolutionary variations in crops (El-Kafafi et al., 2015).OBJECTIVES The present study was directed first time with the aim to investigate the toxic effect of sodium chloride (0-350 mM) and stress acclimation by pre-treatment of GAᴣ, IAA, and SA on the proteome profile of NM-92 cultivar of a Pakistani green gram.MATERIALS AND METHODSThe present study was replicated thrice in the plant laboratory of Department of Genetics, Faculty of Science, and University of Karachi. The seeds of mung bean cultivar NM-92 were acquired from National Agricultural Research Centre (NARC), Islamabad. These freshly collected 15 seedsˉ1 treatment / replication were divided into two sets. The first was named as sodium chloride (SC) stress treatments were imbibed in sterile distilled water (DW) whereas, second set soaked in gibberellic acid (GAᴣ) (BDH Chemicals, England), indole acetic acid (IAA) (Fluka, Switzerland), and salicylic acid (SA) (J.T. Baker, Holland) in the separate beaker for 24 hours under dark condition. After 24 hours, given ample time to both the sets at room temperature. After recovery, all 20 treatments were sown in the 150 X 30 mm sized petri-dishes containing 0, 50, 150, 250, and 350 millimolar (mM) sodium chloride solution (Fisher Scientific, UK) for 72 hours.Protein extraction: Protein extraction was done by taking 0.3g of seedlings in an ice chilled mortar and crushed by adding 600µL 0.2 M Tris-HCl buffer having pH 7.5 contained 5% SDS (w/v) and 5% 2-mercaptoethanol (v/v). The homogenate was incubated at 0oC for 30 min., boiled in the water bath for 3 min. at 100oC. Samples were centrifuged in Heraeus Biofuge D-37520, Germany for 30 min. at 8000 rpm. The protein supernatant was saved at below 0°C for quantitative and qualitative determination with minor modifications. The total soluble protein content of the samples was estimated via “Bovine Serum Albumin (BSA) standard curve” and explicit in µg protein milligramˉ1 fresh weight of mung seedlings.Bovine serum albumin standard curve (2000 μg/mL): Total protein standard curve was made by dissolving 0.05g of Bovine Serum Albumin (BSA) in 25mL of distilled water. Ten serial dilutions were made from 0.1 mL to 1mL by BSA solution then performed Lowry. A standard curve of total proteins was plotted by taking BSA absorbance at Y-axis and 2000 μg BSA / mL at X-axisSample preparation for SDS-PAGE: For qualitative assessment of total proteins; the 35μL of saved protein supernatant was combined with 15μL of sample diluting buffer (SDB). The SDB was made up of 0.0625 M Tris-HCl pH 6.8 with 2% of SDS, 10% of glycerol, 0.003% of bromophenol blue dye and 5% of 2-mercaptoethanol. Boil the 50μL protein SDB supernatant at 100oC in water bath for 3 min., centrifuged at 6000 rpm for 4 min. The supernatant was loaded on SDS-PAGE gel with the given formulae. The SDS- PAGE: Total proteins were fractionated via SDS-PAGE with 4% stacking and 12% resolving gel. The resolving gel of 12% was made by taking 6mL solution A, 1.8 mL 3 M Tris 1 M HCl buffer pH 8.8, 144μL 10% SDS, 5.74 mL sterile distilled water, 720μL 1.5% ammonium persulphate (APS) in deionized water and 10μL TEMED. While, stacking was composed of 1.25mL of solution A, 2.5mL of 0.5M Tris 1M HCl buffer pH 6.8, 100μL 10% SDS, 1.8 mL of distilled water, 500μL 1.5% APS and 12μL TEMED. Solution A was prepared by conjoining 30% acrylamide and 0.8% N, N’-methylene-bisacrylamide in deionized water. To avoid polymerization in the beaker; the prepared solution was quickly poured into the 3 mm thick gel plates after adding TEMED. The stacking was lined over resolving gel, then combs were inserted between the gel plates of SCIE-PLAS TV-100 separation system, UK, and allowed to polymerize for ½ an hour. After polymerization gel was placed in the tank which were filled with Tris-Glycine buffer (electrode buffer) pH 8.4 then combs were removed. The electrode buffer contained 0.3% Tris, 1.41% Glycine and 0.1% SDS in 2000mL d/w. The gel was pre-run for 15 min. at 60 volts and 120 mA currents. The prepared SDS-PAGE samples were loaded in wells with BlueStepTM Broad Range Protein Marker, AMRESCO, USA as standard and run at 60 volts & 120 mA for about 45 min. When samples entered in resolving gel, and then gave 100 volts and 200 mA currents for around 2.5 hours. Furthermore, electrophoresis was carried out at a constant watt.The Gel was washed with 30% ethanol on Uni Thermo Shaker NTS-1300 EYELA, Japan at the constant shaking for 30 min. Then gels were placed in 10% glacial acetic acid in 50% methanol solution (Fixative) for 24 hours. SDS Gel was stained until protein bands were visible thereat placed as 5% of Methanol in 7.5% acetic acid glacial solution to destain the bands background. SDS-PAGE stain composed of 0.125% coomassie brilliant blue R-250 dissolved in 40% of Methanol and 7% acetic acid glacial solution. The stain was stirred on Magnetic stirrer & hot plate M6/1, Germany for 6-10 hours before used. Photographs were taken by Sanyo digital camera VPC-T1284BL and bands were scored through numbering pattern. Gels preserved in 10% acetic acid solution at 4°C.Interpretation of bands and data analysis: The total soluble protein bands relative mobility calculated by below formulae and Dendrogram was constructed via SPSS v. 20Where,F=(Migrated distance of protein band)/(Migrated distance of dye front)Slop=(Log MW of protein marker lower limit band–log〖MW of protein marker upper limit band )/(RF protein marker lower limit band –RF of protein marker upper limit band)RESULTS:The total soluble proteins extracted from green gram were perceived by SDS-PAGE Blue StepTm broad range biochemical markers. The protein-based marker was used to evaluate the toxic effect of sodium chloride along with pre-treatments of GAᴣ, IAA, and SA on proteome assay. In the current work, seedlings total soluble proteome resolved 24 polypeptide bands ranging from 200 to 17.1 kDa were recognized by using SDS-PAGE. The figure 1 showed Dendrogram assay, which classified the 20 treatments of SC, GAᴣ, IAA and SA into two major clusters where, the cluster I was the largest one (figure 1). Cluster I consisted of 15 treatments that further divided into I-A, and I-B. The pre-treatments of SC50+SA, SC150+SA, SC250+SA, and SC350+IAA were grouped together into C-1 of sub-cluster I-A. The C-2 of sub-cluster I-A, pre-treatment SC350+SA was most diverse among 20 treatments. The C-1 treatments showed 99% homology when compared with each other while, it was 97% similar with C-2. The sub-cluster I-B comprised another 10 treatments, SC0+GAᴣ, SC50+GAᴣ, SC150+GAᴣ, SC250+GAᴣ, SC350+GAᴣ, SC0+IAA, SC50+IAA, SC150+IAA, SC250+IAA, and SC0+SA that were also 99% similar for total proteins. Sub-cluster I-B pre-treatments was exhibiting 94% homology with the sub-cluster I-A. The second cluster was the smallest one that was divided into two sub-clusters, II-A and II-B. The II-A was comprised of SC50, SC150, and SC250 while, sub-cluster II-B consisted of SC0 and SC350. Within each sub-cluster, pre-treatments expressed 99% homology whereas, II-A was 97 different from II-B. Furthermore, cluster I showed 75% similarities with cluster II (figure 1). The seedlings storage proteome profile of green gram was shown in table 1.The results showed that 120kDa, 114.6 kDa, 51.8 kDa, 29.1 kDa and 22.8 kDa proteins bands were not induced at 0 mM SC, GAᴣ, IAA, and SA. The table 1 depicted the presence of 120 kDa and 114.6 kDa bands only at 350 mM SC level with all phytohormones treatments. Similarly, 51.8 kDa protein bands were appearing at 150SC, 250SC and 350SC stress with phytohormones. Based on the information collected from the NCBI protein database, this peptide was related to the 8S globulin alpha subunits. The two other, 7S globulins sub-units having 29.1kDa and 22.8 kDa molecular weights bands were synthesized under 50mM, 150mM, 250mM, 350mM SC stress with phytohormones. Concerning protein polypeptide of molecular weight 104.5 kDa, 99.8 kDa, 91.0 kDa, 55.0 kDa, and 46.0 kDa, those were induced by GAᴣ, IAA and SA at 0 to 350 mM SC. While, 17kDa protein band was appearing in SA, and IAA treated samples and 95.3kDa band was only present in SA treatment. Other 12 protein bands were present in all treatments proved as house-keeping proteins of green gram (table 1).DISCUSSIONThe SDS-PAGE profiling for proteome is the reliable and applied biochemical approach that has been used as biochemical marker in various crop differentiation, and characterization. In the current study, first time SDS-PAGE was utilized to investigate the impact of GAᴣ, IAA, and SA pre-soaking on green gram under salt toxicity. The salt toxicity adversely affects all seed, seedling, and plant metabolic process (Parveen et al., 2016). At salt toxicity, the endogenous GAᴣ, IAA, and SA levels markedly decrease (El-Khallal et al., 2009). In such condition, exogenous application of GAᴣ, IAA, and SA enhance seedlings survival rate by increasing synthesis of seed storage proteins. Likewise, our Dendrogram characterization based on 20 treatments showed significant diversity under 0 to 350 mM SC stress. The salicylic acid treatments were grouped together except SC0+SA treatment, exhibiting a close relationship, which proved its acclimating role under salt stress. These findings will help plant breeder toward enhancing food quality and quantity of green gram in future breeding programme on saline sodic land.The SDS-PAGE assay revealed 200. kDa, 109.4 kDa, 77 kDa, 68 kDa, 49 kDa, 38 kDa, 33 kDa, 26 kDa, 24 kDa, 22 kDa, 21 kDa and 19 kDa fractions as essential green gram proteins. Among these, 68 kDa, 49 kDa, 33 kDa, 26 kDa, 24 kDa and 21 kDa peptides were seed biotinylated isoform protein (Riascos et al., 2009), putative NADH-ubiquinone oxidoreductase subunit H (Gostinčar et al., 2019), heat shock protein 33 (Hamidian et al., 2015), globulin protein, seed coat / maturation protein (Dhaubhadel et al., 2005), and protein for dimerization. While, 22 kDa proteins belonged to the class of prolamin alpha zein Z1C1_2, Z1C1_4, and Z1C1_8 precursors, and 19kDa peptide was related with Z1A1_2, Z1A2_2, and Z1B_6 precursors (Miclaus et al., 2011). Further, the 91 kDa peptide is sucrose synthase SS1 protein, and 77kDa protein is the NADPH-cytochrome P450 reductase (Wang et al., 2004). Also, the phosphatase-associated two other proteins having 46 and 55 kDa molecular weight were reported earlier in Mucuna pruriens. Hameed et al. (2012) and Malviya et al. (2008) found 55 and 46kDa peptides as 7S vicilin small sub-units and 17kDa as 11S globulins sub-unit in the studied Vigna radiata. Some other molecular weight proteome such as 68 kDa and 49kDa are 7S vicilin, 33kDa is 8S vicilin, 38 and 26kDa 8S globulins, 24kDa 11S globulins, and 22kDa 16.5S globulins. These proteins required for germination and seed establishment of green gram plant (Hameed et al., 2012).The vast accumulation of 23kDa and 22kDa peptides under salt stress by salicylic acid, were reported previously in the mangrove Bruguiera parviffora and Zea mays (El-Khallal et al., 2009). Correspondingly, El-Kafafi et al. (2015) reported the presence of 115kDa, 23kDa, and 22kDa bands in the salt tolerant lines of green gram. These proteomes induced under salt stress may play a pivotal part in the stress acclimation and osmotic adjustment. Similarly, the induction of 104 kDa and 100kDa MW polypeptide by SC stress in the salt tolerant genotypes of green gram indicated the functional role of phytohormones in various metabolic and defense response El-Kafafi et al. (2015); Alharby et al. (2016), El-Khallal et al. (2009), Qados (2010). Ali et al. (2007), Alharby et al. (2016), and El-Kafafi et al. (2015) observed 17kDa, 26kDa, 33kDa and 77kDa bands involving in salt tolerance and can be considered as a positive biochemical marker for salt stress. Further, 26 kDa MW peptide also functions as osmotin under the salt stress that involved in enhancing the accumulation of glycine betaine and proline in the cells. Hence, proteome assay of green gram showed that GAᴣ, IAA, and SA could regulate the expression of salt stress proteins that are anticipated to play a crucial part in the salt tolerance mechanism. Likewise, the involvement of phytohormones in the induction of changes in the proteome profile pattern was attributed to their part in managing cell division by regulating some genes of apical meristems.CONCLUSIONFinally, the results revealed the presence of the ten new bands with MW of 200kDa, 120 kDa, 114.6 kDa, 109.4kDa, 104.5kDa, 99.8kDa, 95.3kDa, 51.8kDa, 29.1kDa and 22.8kDa have not reported previously under salt stress with phytohormones treatments in green gram. Furthermore, it was observed that phytohormones alleviate the negative impact of salt stress on green gram by enhancing synthesis of salt defense polypeptides. Hence, higher accumulation of proteins was observed in salicylic acid treated seedlings. Thus, present work recommended the pre-soaking of phytohormones to overcome the toxic impact of sodium chloride on green gram. Further research is needed on a biomolecular level to reveal the mechanism of signalling pathways under sever salt stress.CONFLICT OF INTERESTBoth authors have declared that no disagreement of interest regarding this research.REFERENCES Alharby, H. F., E. M. Metwali, M. P. Fuller and A. Y. Aldhebiani, 2016. The alteration of mRNA expression of sod and gpx genes, and proteins in tomato (Lycopersicon esculentum Mill) under stress of Nacl and/or ZnO nanoparticles. Saudi journal of biological sciences, 23(6): 773-781.Ali, A., M. Mageed, I. Ahmed and S. Mariey, 2007. Genetic and molecular studies on barley salt tolerance. In: African crop science conference proceedings. pp: 669-682.Chadha, M., 2010. Short duration mungbean: A new success in South Asia. Asia-Pacific association of agricultural research institutions.Dhaubhadel, S., K. Kuflu, M. C. Romero and M. Gijzen, 2005. A soybean seed protein with carboxylate-binding activity. 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Background: Acinetobacter baumannii was considered as a low priority pathogen earlier, and is been now reported as a priority pathogen causing nosocomial infections. Selection of natural compounds to target the organism is the need of the hour. Aim: This study is aimed to target the KpsM protein of A. baumannii with the bio-compounds from Azadirachta indica using in-silico docking analysis. Materials and Methods: KpsM protein was retrieved and optimisation of protein was done. After that optimization and ligand preparation was carried out. It was continued by molinspiration assessment of the molecular properties of selected compounds. It was followed by docking simulation and docking visualisation. Results: Out of the 7 compounds of Azadirachta indica, dihydro diisoeugenol is the best compound to act on the KpsM protein of Acinetobacter baumannii and a binding energy of -6.83Kcal/Mol. Conclusion: The findings of the study reports isoeugenol with more binding energy than other compounds towards the selected protein KpsM of Acinetobacter baumannii. However it requires further experimental studies to understand the mechanism of its actions and safety.

Limited therapeutic options dictate the need for new classes of antimicrobials active against carbapenem-resistant Acinetobacter baumannii . Presented data confirm and extend penicillin binding protein 7/8 (PBP 7/8) as a high-value target in the CR A. baumannii strain HUMC1.

Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two‐domain proteins with an N‐terminal eight‐stranded β‐barrel domain with four external loops (ELs) interacting with the environment, and a C‐terminal periplasmic domain binding non‐covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus / Acinetobacter baumannii complex (ACB), 946 from A. baumannii , to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii , encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C‐terminal end, and provided evidence for intra‐genic recombination. ompA variants were not randomly distributed across the A . baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A . baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.