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Auteur : Grafiati
Publié le 25 mai 2024

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1

Alhadlaq, Meshari Ahmed, Jeffrey Green et Bassam K. Kudhair. « Analysis of Kytococcus sedentarius Strain Isolated from a Dehumidifier Operating in a University Lecture Theatre : Systems for Aerobic Respiration, Resisting Osmotic Stress, and Sensing Nitric Oxide ». Microbial Physiology 31, no 2 (2021) : 135–45. http://dx.doi.org/10.1159/000512751.

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A strain of <i>Kytococcus sedentarius</i> was isolated from a dehumidifier operating in a university lecture theatre. Genome analysis and phenotypic characterisation showed that this strain, <i>K. sedentarius</i> MBB13, was a moderately halotolerant aerobe with a branched aerobic electron transport chain and genes that could contribute to erythromycin resistance. The major compatible solute was glycine betaine, with ectoine and proline being deployed at higher osmolarities. Actinobacteria possess multiple WhiB-like (Wbl) regulatory proteins, and <i>K. sedentarius</i> MBB13 has four (WhiB1, WhiB2, WhiB3, and WhiB7). Wbls are iron-sulfur proteins that regulate gene expression through interactions with RNA polymerase sigma factors and/or other regulatory proteins. Bacterial two-hybrid analyses suggested that WhiB1 and WhiB2, but not WhiB3 and WhiB7, interact with the C-terminal domain of the major sigma factor, σ<sup>A</sup>; no interaction was detected between any of the Wbl proteins and the only alternative sigma factors, σ<sup>B</sup>, σ<sup>H</sup>, or σ<sup>J</sup>. The interaction between σ<sup>A</sup> and WhiB1 or WhiB2 was disrupted in a heterologous system under growth conditions that produce nitric oxide and the iron-sulfur clusters of the isolated WhiB1 and WhiB2 proteins reacted with nitric oxide. Thus, <i>K. sedentarius</i> strain exhibits the major phenotypic characteristics of the type strain and a comprehensive examination of the interactions between its four Wbl proteins and four sigma factors suggested that the Wbl proteins all operate through interaction with σ<sup>A</sup>.
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Geiman, Deborah E., Tirumalai R. Raghunand, Nisheeth Agarwal et William R. Bishai. « Differential Gene Expression in Response to Exposure to Antimycobacterial Agents and Other Stress Conditions among Seven Mycobacterium tuberculosis whiB-Like Genes ». Antimicrobial Agents and Chemotherapy 50, no 8 (août 2006) : 2836–41. http://dx.doi.org/10.1128/aac.00295-06.

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ABSTRACT The seven Mycobacterium tuberculosis whiB-like genes encode small proteins postulated to be transcriptional regulators. A systematic real-time reverse transcription-PCR analysis following exposure to antibiotics and a variety of growth and in vitro stress conditions indicates differential, and in some cases dramatic, transcription modulations for the different M. tuberculosis whiB family members. This information together with biochemical analyses of the whiB1 to whiB7 gene products will be important for understanding the biology of this novel family of proteins in mycobacteria and related actinomycetes.
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Bosserman, Rachel E., Tiffany T. Nguyen, Kevin G. Sanchez, Alexandra E. Chirakos, Micah J. Ferrell, Cristal R. Thompson, Matthew M. Champion, Robert B. Abramovitch et Patricia A. Champion. « WhiB6 regulation of ESX-1 gene expression is controlled by a negative feedback loop inMycobacterium marinum ». Proceedings of the National Academy of Sciences 114, no 50 (27 novembre 2017) : E10772—E10781. http://dx.doi.org/10.1073/pnas.1710167114.

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ESX (ESAT-6 system) export systems play diverse roles across mycobacterial species. Interestingly, genetic disruption of ESX systems in different species does not result in an accumulation of protein substrates in the mycobacterial cell. However, the mechanisms underlying this observation are elusive. We hypothesized that the levels of ESX substrates were regulated by a feedback-control mechanism, linking the levels of substrates to the secretory status of ESX systems. To test this hypothesis, we used a combination of genetic, transcriptomic, and proteomic approaches to define export-dependent mechanisms regulating the levels of ESX-1 substrates inMycobacterium marinum. WhiB6 is a transcription factor that regulates expression of genes encoding ESX-1 substrates. We found that, in the absence of the genes encoding conserved membrane components of the ESX-1 system, the expression of thewhiB6gene and genes encoding ESX-1 substrates were reduced. Accordingly, the levels of ESX-1 substrates were decreased, and WhiB6 was not detected inM. marinumstrains lacking genes encoding ESX-1 components. We demonstrated that, in the absence of EccCb1, a conserved ESX-1 component, substrate gene expression was restored by constitutive, but not native, expression of thewhiB6gene. Finally, we found that the loss of WhiB6 resulted in a virulentM. marinumstrain with reduced ESX-1 secretion. Together, our findings demonstrate that the levels of ESX-1 substrates inM. marinumare fine-tuned by negative feedback control, linking the expression of thewhiB6gene to the presence, not the functionality, of the ESX-1 membrane complex.
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Murarka, Pooja, Aditi Keshav, Bintu Kumar Meena et Preeti Srivastava. « Functional characterization of the transcription regulator WhiB1 from Gordonia sp. IITR100 ». Microbiology 166, no 12 (1 décembre 2020) : 1181–90. http://dx.doi.org/10.1099/mic.0.000985.

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WhiB is a transcription regulator which has been reported to be involved in the regulation of cell morphogenesis, cell division, antibiotic resistance, stress, etc., in several members of the family Actinomycetes . The present study describes functional characterization of a WhiB family protein, WhiB1 (protein ID: WP_065632651.1), from Gordonia sp. IITR100. We demonstrate that WhiB1 affects chromosome segregation and cell morphology in recombinant Escherichia coli , Gordonia sp. IITR100 as well as in Rhodococcus erythropolis . Multiple sequence alignment suggests that WhiB1 is a conserved protein among members of the family Actinomycetes . It has been reported that overexpression of WhiB1 leads to repression of the biodesulfurization operon in recombinant E. coli , Gordonia sp. IITR100 and R. erythropolis . A WhiB1-mut containing a point mutation Q116A in the DNA binding domain of WhiB1 led to partial alleviation of repression of the biodesulfurization operon. We show for the first time that the WhiB family protein WhiB1 is also involved in repression of the biodesulfurization operon by directly binding to the dsz promoter DNA.
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Raghunand, Tirumalai R., et William R. Bishai. « Mapping Essential Domains of Mycobacterium smegmatis WhmD : Insights into WhiB Structure and Function ». Journal of Bacteriology 188, no 19 (1 octobre 2006) : 6966–76. http://dx.doi.org/10.1128/jb.00384-06.

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ABSTRACT A growing body of evidence suggests that the WhiB-like proteins exclusive to the GC-rich actinomycete genera play significant roles in pathogenesis and cell division. Each of these proteins contains four invariant cysteine residues and a conserved helix-turn-helix motif. whmD, the Mycobacterium smegmatis homologue of Streptomyces coelicolor whiB, is essential in M. smegmatis, and the conditionally complemented mutant M. smegmatis 628-53 undergoes filamentation under nonpermissive conditions. To identify residues critical to WhmD function, we developed a cotransformation-based assay to screen for alleles that complement the filamentation phenotype of M. smegmatis 628-53 following inducer withdrawal. Mycobacterium tuberculosis whiB2 and S. coelicolor whiB complemented the defect in M. smegmatis 628-53, indicating that these genes are true functional orthologues of whmD. Deletion analysis suggested that the N-terminal 67 and C-terminal 12 amino acid residues are dispensable for activity. Site-directed mutagenesis indicated that three of the four conserved cysteine residues (C90, C93, and C99) and a conserved aspartate (D71) are essential. Mutations in a predicted loop glycine (G111) and an unstructured leucine (L116) were poorly tolerated. The region essential for WhmD activity encompasses 6 of the 10 residues conserved in all seven M. tuberculosis WhiBs, as well as in most members of the WhiB family identified thus far. WhmD structure was found to be sensitive to the presence of a reducing agent, suggesting that the cysteine residues are involved in coordinating a metal ion. Iron-specific staining strongly suggested that WhmD contains a bound iron atom. With this information, we have now begun to comprehend the functional significance of the conserved sequence and structural elements in this novel family of proteins.
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Vijayaraj, Mahalakshmi. « Virtual screening of a MDR-TB WhiB6 target identified by gene expression profiling ». Bioinformation 15, no 8 (31 août 2019) : 557–67. http://dx.doi.org/10.6026/97320630015557.

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Agarwal, Nisheeth, Tirumalai R. Raghunand et William R. Bishai. « Regulation of the expression of whiB1 in Mycobacterium tuberculosis : role of cAMP receptor protein ». Microbiology 152, no 9 (1 septembre 2006) : 2749–56. http://dx.doi.org/10.1099/mic.0.28924-0.

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The wbl (whiB-like) genes encode putative transcription factors unique to actinomycetes. This study characterized the promoter element of one of the seven wbl genes of Mycobacterium tuberculosis, whiB1 (Rv3219c). The results reveal that whiB1 is transcribed by a class I-type cAMP receptor protein (CRP)-dependent promoter, harbouring a CRP-binding site positioned at −58.5 with respect to its transcription start point. In vivo promoter activity analysis and electrophoretic mobility shift assays suggest that the expression of whiB1 is indeed regulated by cAMP-dependent binding of CRPM (encoded by the M. tuberculosis gene Rv3676) to the whiB1 5′ untranslated region (5′UTR). β-Galactosidase gene fusion analysis revealed induction of the whiB1 promoter in M. tuberculosis on addition of exogenous dibutyric cAMP (a diffusible cAMP analogue) only when an intact CRP-binding site was present. These results indicate that M. tuberculosis whiB1 transcription is regulated in part by cAMP levels via direct binding of cAMP-activated CRPM to a consensus CRP-binding site in the whiB1 5′UTR.
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Wan, Tao, Shanren Li, Daisy Guiza Beltran, Andrew Schacht, Lu Zhang, Donald F. Becker et LiMei Zhang. « Structural basis of non-canonical transcriptional regulation by the σA-bound iron-sulfur protein WhiB1 in M. tuberculosis ». Nucleic Acids Research 48, no 2 (6 décembre 2019) : 501–16. http://dx.doi.org/10.1093/nar/gkz1133.

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Abstract WhiB1 is a monomeric iron–sulfur cluster-containing transcription factor in the WhiB-like family that is widely distributed in actinobacteria including the notoriously persistent pathogen Mycobacterium tuberculosis (M. tuberculosis). WhiB1 plays multiple roles in regulating cell growth and responding to nitric oxide stress in M. tuberculosis, but its underlying mechanism is unclear. Here we report a 1.85 Å-resolution crystal structure of the [4Fe–4S] cluster-bound (holo-) WhiB1 in complex with the C-terminal domain of the σ70-family primary sigma factor σA of M. tuberculosis containing the conserved region 4 (σA4). Region 4 of the σ70-family primary sigma factors is commonly used by transcription factors for gene activation, and holo-WhiB1 has been proposed to activate gene expression via binding to σA4. The complex structure, however, unexpectedly reveals that the interaction between WhiB1 and σA4 is dominated by hydrophobic residues in the [4Fe–4S] cluster binding pocket, distinct from previously characterized canonical σ704-bound transcription activators. Furthermore, we show that holo-WhiB1 represses transcription by interaction with σA4in vitro and that WhiB1 must interact with σA4 to perform its essential role in supporting cell growth in vivo. Together, these results demonstrate that holo-WhiB1 regulates gene expression by a non-canonical mechanism relative to well-characterized σA4-dependent transcription activators.
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Chen, Zhenkang, Yangbo Hu, Bridgette M. Cumming, Pei Lu, Lipeng Feng, Jiaoyu Deng, Adrie J. C. Steyn et Shiyun Chen. « Mycobacterial WhiB6 Differentially Regulates ESX-1 and the Dos Regulon to Modulate Granuloma Formation and Virulence in Zebrafish ». Cell Reports 16, no 9 (août 2016) : 2512–24. http://dx.doi.org/10.1016/j.celrep.2016.07.080.

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Casonato, Stefano, Axel Cervantes Sánchez, Hirohito Haruki, Monica Rengifo González, Roberta Provvedi, Elisa Dainese, Thomas Jaouen et al. « WhiB5, a Transcriptional Regulator That Contributes to Mycobacterium tuberculosis Virulence and Reactivation ». Infection and Immunity 80, no 9 (25 juin 2012) : 3132–44. http://dx.doi.org/10.1128/iai.06328-11.

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ABSTRACTThe proteins belonging to the WhiB superfamily are small global transcriptional regulators typical of actinomycetes. In this paper, we characterize the role of WhiB5, aMycobacterium tuberculosisprotein belonging to this superfamily. A null mutant was constructed inM. tuberculosisH37Rv and was shown to be attenuated during both progressive and chronic mouse infections. Mice infected with the mutant had smaller bacillary burdens in the lungs but a larger inflammatory response, suggesting a role of WhiB5 in immunomodulation. Most interestingly, thewhiB5mutant was not able to resume growth after reactivation from chronic infection, suggesting that WhiB5 controls the expression of genes involved in this process. The mutant was also more sensitive than the wild-type parental strain toS-nitrosoglutathione (GSNO) and was less metabolically active following prolonged starvation, underscoring the importance of GSNO and starvation in development and maintenance of chronic infection. DNA microarray analysis identified 58 genes whose expression is influenced by WhiB5, includingsigM, encoding an alternative sigma factor, and genes encoding the constituents of two type VII secretion systems, namely, ESX-2 and ESX-4.
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Solans, Luis, Nacho Aguiló, Sofía Samper, Alexandre Pawlik, Wafa Frigui, Carlos Martín, Roland Brosch et Jesús Gonzalo-Asensio. « A Specific Polymorphism in Mycobacterium tuberculosis H37Rv Causes Differential ESAT-6 Expression and Identifies WhiB6 as a Novel ESX-1 Component ». Infection and Immunity 82, no 8 (2 juin 2014) : 3446–56. http://dx.doi.org/10.1128/iai.01824-14.

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ABSTRACTThe ESX-1 secreted virulence factor ESAT-6 is one of the major and most well-studied virulence factors ofMycobacterium tuberculosis, given that its inactivation severely attenuates virulent mycobacteria. In this work, we show that clinical isolates ofM. tuberculosisproduce and secrete larger amounts of ESAT-6 than the widely usedM. tuberculosisH37Rv laboratory strain. A search for the genetic polymorphisms underlying this observation showed thatwhiB6(rv3862c), a gene upstream of the ESX-1 genetic locus that has not previously been found to be implicated in the regulation of the ESX-1 secretory apparatus, presents a unique single nucleotide insertion in its promoter region in strains H37Rv and H37Ra. This polymorphism is not present in any of the other publicly availableM. tuberculosiscomplex genomes or in any of the 76 clinicalM. tuberculosisisolates analyzed in our laboratory. We demonstrate that in consequence, the virulence master regulator PhoP downregulateswhiB6expression in H37Rv, while it upregulates its expression in clinical strains. Importantly, reintroduction of the wild-type (WT) copy ofwhiB6in H37Rv restored ESAT-6 production and secretion to the level of clinical strains. Hence, we provide clear evidence that inM. tuberculosis—with the exception of the H37Rv strain—ESX-1 expression is regulated by WhiB6 as part of the PhoP regulon, which adds another level of complexity to the regulation of ESAT-6 secretion with a potential role in virulence adaptation.
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Abdallah, Abdallah M., Eveline M. Weerdenburg, Qingtian Guan, Roy Ummels, Stephanie Borggreve, Sabir A. Adroub, Tareq B. Malas et al. « Integrated transcriptomic and proteomic analysis of pathogenic mycobacteria and their esx-1 mutants reveal secretion-dependent regulation of ESX-1 substrates and WhiB6 as a transcriptional regulator ». PLOS ONE 14, no 1 (23 janvier 2019) : e0211003. http://dx.doi.org/10.1371/journal.pone.0211003.

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Rybniker, Jan, Angela Nowag, Edeltraud Van Gumpel, Nicole Nissen, Nirmal Robinson, Georg Plum et Pia Hartmann. « Insights into the function of the WhiB-like protein of mycobacteriophage TM4 - a transcriptional inhibitor of WhiB2 ». Molecular Microbiology 77, no 3 (11 juin 2010) : 642–57. http://dx.doi.org/10.1111/j.1365-2958.2010.07235.x.

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Smith, Laura J., Melanie R. Stapleton, Gavin J. M. Fullstone, Jason C. Crack, Andrew J. Thomson, Nick E. Le Brun, Debbie M. Hunt et al. « Mycobacterium tuberculosis WhiB1 is an essential DNA-binding protein with a nitric oxide-sensitive iron–sulfur cluster ». Biochemical Journal 432, no 3 (25 novembre 2010) : 417–27. http://dx.doi.org/10.1042/bj20101440.

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Mycobacterium tuberculosis is a major pathogen that has the ability to establish, and emerge from, a persistent state. Wbl family proteins are associated with developmental processes in actinomycetes, and M. tuberculosis has seven such proteins. In the present study it is shown that the M. tuberculosis H37Rv whiB1 gene is essential. The WhiB1 protein possesses a [4Fe-4S]2+ cluster that is stable in air but reacts rapidly with eight equivalents of nitric oxide to yield two dinuclear dinitrosyl-iron thiol complexes. The [4Fe-4S] form of WhiB1 did not bind whiB1 promoter DNA, but the reduced and oxidized apo-WhiB1, and nitric oxide-treated holo-WhiB1 did bind to DNA. Mycobacterium smegmatis RNA polymerase induced transcription of whiB1 in vitro; however, in the presence of apo-WhiB1, transcription was severely inhibited, irrespective of the presence or absence of the CRP (cAMP receptor protein) Rv3676, which is known to activate whiB1 expression. Footprinting suggested that autorepression of whiB1 is achieved by apo-WhiB1 binding at a region that overlaps the core promoter elements. A model incorporating regulation of whiB1 expression in response to nitric oxide and cAMP is discussed with implications for sensing two important signals in establishing M. tuberculosis infections.
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Hurst-Hess, Kelley, Charity McManaman, Yong Yang, Shamba Gupta et Pallavi Ghosh. « Hierarchy and interconnected networks in the WhiB7 mediated transcriptional response to antibiotic stress in Mycobacterium abscessus ». PLOS Genetics 19, no 12 (6 décembre 2023) : e1011060. http://dx.doi.org/10.1371/journal.pgen.1011060.

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Mycobacterium abscessus is intrinsically resistant to antibiotics effective against other pathogenic mycobacteria largely due to the drug-induced expression of genes that confer resistance. WhiB7 is a major hub controlling the induction of resistance to ribosome-targeting antibiotics. It activates the expression of >100 genes, 7 of which are known determinants of drug resistance; the function of most genes within the regulon is however unknown, but some conceivably encode additional mechanisms of resistance. Furthermore, the hierarchy of gene expression within the regulon, if any, is poorly understood. In the present work we have identified 56 WhiB7 binding sites using chromatin immunoprecipitation sequencing (CHIP-Seq) which accounts for the WhiB7-dependent upregulation of 72 genes, and find that M. abscessus WhiB7 functions exclusively as a transcriptional activator at promoters recognized by σA/σB. We have investigated the role of 18 WhiB7 regulated genes in drug resistance. Our results suggest that while some genes within the regulon (eg. erm41, hflX, eis2 and the ABCFs) play a major role in resistance, others make smaller contributions (eg. MAB_4324c and MAB_1409c) and the observed hypersensitivity ΔMabwhiB7 is a cumulative effect of these individual contributions. Moreover, our CHIP-Seq data implicate additional roles of WhiB7 induced genes beyond antibiotic resistance. Finally, we identify a σH-dependent network in aminoglycoside and tigecycline resistance which is induced upon drug exposure and is further activated by WhiB7 demonstrating the existence of a crosstalk between components of the WhiB7-dependent and -independent circuits.
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Aziz, Dinah Binte, Mei Lin Go et Thomas Dick. « Rifabutin Suppresses Inducible Clarithromycin Resistance in Mycobacterium abscessus by Blocking Induction of whiB7 and erm41 ». Antibiotics 9, no 2 (10 février 2020) : 72. http://dx.doi.org/10.3390/antibiotics9020072.

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Clarithromycin (CLR) is the corner stone in regimens for the treatment of lung disease caused by Mycobacterium abscessus (Mab). However, many strains harbor the CLR-inducible CLR resistance gene erm41, encoding a ribosome methylase. Induction of erm41 is mediated by the transcription factor whiB7. We hypothesized that an inhibitor of RNA synthesis should be able to block the whiB7–erm41 induction response to CLR exposure and thus suppress CLR resistance. Recently, we discovered that the rifampicin analog rifabutin (RFB) shows attractive potency against Mab. To determine whether RFB-CLR combinations are synergistic, a checkerboard analysis against a collection of erm41 positive and negative Mab strains was carried out. This revealed synergy of the two drugs for erm41 positive but not for erm41 negative strains. To determine whether RFB’s potentiation effect was due to inhibition of the transcriptional induction of the whiB7–erm41 resistance system, we measured the effect of CLR alone and in combination with RFB on whiB7 and erm41 mRNA levels. CLR alone strongly induced whiB7 and erm41 expression as expected. The synergistic, growth-inhibiting combination of RFB with CLR blocked induction of both genes. These results suggest that RFB suppresses inducible CLR resistance by preventing induction of whiB7 and erm41 expression.
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Banaiee, N., W. R. Jacobs et J. D. Ernst. « Regulation of Mycobacterium tuberculosis whiB3 in the Mouse Lung and Macrophages ». Infection and Immunity 74, no 11 (21 août 2006) : 6449–57. http://dx.doi.org/10.1128/iai.00190-06.

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ABSTRACT Mycobacterium tuberculosis is a highly successful human pathogen, with ∼2 × 109 individuals infected globally. To understand the responses of M. tuberculosis to the in vivo environment, we studied the in vivo regulation of M. tuberculosis genes whose M. marinum homologs are induced in chronically infected frog tissues. The expression of 16S rRNA was shown to remain constant in M. tuberculosis under in vivo and in vitro conditions and therefore could be used for internal normalization in quantitative reverse transcription-PCR assays. We found whiB3, a putative transcriptional regulator implicated in mediating tissue damage, to be maximally induced at 2 weeks postinfection in the lungs of wild-type and immunodeficient (gamma interferon receptor−/−, Rag1−/−, and tumor necrosis factor alpha−/−) mice. At later time points in wild-type mice, whiB3 induction was decreased and gradually declined over the course of infection. In immunodeficient mice, whiB3 induction declined rapidly and was completely abolished in moribund animals. whiB3 was also found to be induced in naïve bone marrow-derived macrophages after 6 h of infection. whiB3 expression in vivo and in vitro was found to be inversely correlated with bacterial density. These results indicate that M. tuberculosis regulates the expression of whiB3 in response to environmental signals present in vivo and are consistent with a model of regulation by quorum sensing.
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Hümpel, Anja, Susanne Gebhard, Gregory M. Cook et Michael Berney. « The SigF Regulon in Mycobacterium smegmatis Reveals Roles in Adaptation to Stationary Phase, Heat, and Oxidative Stress ». Journal of Bacteriology 192, no 10 (16 mars 2010) : 2491–502. http://dx.doi.org/10.1128/jb.00035-10.

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ABSTRACTSigF is an alternative sigma factor that is highly conserved among species of the genusMycobacterium. In this study we identified the SigF regulon inMycobacterium smegmatisusing whole-genome microarray and promoter consensus analyses. In total, 64 genes in exponential phase and 124 genes in stationary phase are SigF dependent (P< 0.01, >2-fold expression change). Our experimental data reveal the SigF-dependent promoter consensus GTTT-N(15-17)-GGGTA forM. smegmatis, and we propose 130 potential genes under direct control of SigF, of which more than 50% exhibited reduced expression in a ΔsigFstrain. We previously reported an increased susceptibility of the ΔsigFstrain to heat and oxidative stress, and our expression data indicate a molecular basis for these phenotypes. We observed SigF-dependent expression of several genes purportedly involved in oxidative stress defense, namely, a heme-containing catalase, a manganese-containing catalase, a superoxide dismutase, the starvation-induced DNA-protecting protein MsDps1, and the biosynthesis genes for the carotenoid isorenieratene. Our data suggest that SigF regulates the biosynthesis of the thermoprotectant trehalose, as well as an uptake system for osmoregulatory compounds, and this may explain the increased heat susceptibility of the ΔsigFstrain. We identified the regulatory proteins SigH3, PhoP, WhiB1, and WhiB4 as possible genes under direct control of SigF and propose four novel anti-sigma factor antagonists that could be involved in the posttranslational regulation of SigF inM. smegmatis. This study emphasizes the importance of this sigma factor for stationary-phase adaptation and stress response in mycobacteria.
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Barrientos, Omar M., Elizabeth Langley, Yolanda González, Carlos Cabello, Martha Torres et Silvia Guzmán-Beltrán. « Mycobacterium tuberculosis whiB3 and Lipid Metabolism Genes Are Regulated by Host Induced Oxidative Stress ». Microorganisms 10, no 9 (11 septembre 2022) : 1821. http://dx.doi.org/10.3390/microorganisms10091821.

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The physiological state of the human macrophage may impact the metabolism and the persistence of Mycobacterium tuberculosis. This pathogen senses and counters the levels of O2, CO, reactive oxygen species (ROS), and pH in macrophages. M. tuberculosis responds to oxidative stress through WhiB3. The goal was to determine the effect of NADPH oxidase (NOX) modulation and oxidative agents on the expression of whiB3 and genes involved in lipid metabolism (lip-Y, Icl-1, and tgs-1) in intracellular mycobacteria. Human macrophages were first treated with NOX modulators such as DPI (ROS inhibitor) and PMA (ROS activator), or with oxidative agents (H2O2 and generator system O2•−), and then infected with mycobacteria. We determined ROS production, cell viability, and expression of whiB3, as well as genes involved in lipid metabolism. PMA, H2O2, and O2•− increased ROS production in human macrophages, generating oxidative stress in bacteria and augmented the gene expression of whiB3, lip-Y, Icl-1, and tgs-1. Our results suggest that ROS production in macrophages induces oxidative stress in intracellular bacteria inducing whiB3 expression. This factor may activate the synthesis of reserve lipids produced to survive in the latency state, which allows its persistence for long periods within the host.
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Raghunand, Tirumalai R., et William R. Bishai. « Mycobacterium smegmatis whmD and its homologue Mycobacterium tuberculosis whiB2 are functionally equivalent ». Microbiology 152, no 9 (1 septembre 2006) : 2735–47. http://dx.doi.org/10.1099/mic.0.28911-0.

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Mycobacterium smegmatis whmD is is an essential gene involved in cell division. This paper shows that whmD and its homologue whiB2 in Mycobacterium tuberculosis are functionally equivalent. The genes are syntenous, and share significant homology in both their coding and non-coding DNA sequences. Transcription site mapping showed that the two genes possess near-identical promoter elements, and they displayed comparable promoter strengths in a reporter gene assay. The two proteins show near identity in their C-terminus, and polyclonal antiserum to WhmD specifically cross-reacts with a ∼15 kDa band in M. tuberculosis lysates. Following overexpression of sense and anti-sense constructs in their cognate mycobacterial hosts, whiB2 and whmD transformants displayed a small-colony phenotype, exhibited filamentation, and showed a reduction in viability. These observations reveal that the two proteins are functionally homologous and that their intracellular concentration is critical for septation in mycobacteria. Colonies of M. tuberculosis overexpressing whiB2 were spherical and glossy, suggesting a change in composition of the cell envelope. Filaments of the conditionally complemented M. smegmatis whmD mutant were non-acid-fast, also indicating changes in characteristics of surface lipids. M. smegmatis transformants carrying a whmD–gfp fusion showed a diffuse pattern of fluorescence, consistent with the putative role of WhmD as a regulator. These observations strongly suggest that M. tuberculosis whiB2 is an essential gene and its protein product in all likelihood regulates the expression of genes involved in the cell division cascade.
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Schrader, Sarah M., Hélène Botella, Robert Jansen, Sabine Ehrt, Kyu Rhee, Carl Nathan et Julien Vaubourgeix. « Multiform antimicrobial resistance from a metabolic mutation ». Science Advances 7, no 35 (août 2021) : eabh2037. http://dx.doi.org/10.1126/sciadv.abh2037.

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A critical challenge for microbiology and medicine is how to cure infections by bacteria that survive antibiotic treatment by persistence or tolerance. Seeking mechanisms behind such high survival, we developed a forward-genetic method for efficient isolation of high-survival mutants in any culturable bacterial species. We found that perturbation of an essential biosynthetic pathway (arginine biosynthesis) in a mycobacterium generated three distinct forms of resistance to diverse antibiotics, each mediated by induction of WhiB7: high persistence and tolerance to kanamycin, high survival upon exposure to rifampicin, and minimum inhibitory concentration–shifted resistance to clarithromycin. As little as one base change in a gene that encodes, a metabolic pathway component conferred multiple forms of resistance to multiple antibiotics with different targets. This extraordinary resilience may help explain how substerilizing exposure to one antibiotic in a regimen can induce resistance to others and invites development of drugs targeting the mediator of multiform resistance, WhiB7.
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Zheng, Fei, Quanxin Long et Jianping Xie. « The Function and Regulatory Network of WhiB and WhiB-Like Protein from Comparative Genomics and Systems Biology Perspectives ». Cell Biochemistry and Biophysics 63, no 2 (3 mars 2012) : 103–8. http://dx.doi.org/10.1007/s12013-012-9348-z.

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Chawla, Manbeena, Saurabh Mishra, Kushi Anand, Pankti Parikh, Mansi Mehta, Manika Vij, Taru Verma et al. « Redox-dependent condensation of the mycobacterial nucleoid by WhiB4 ». Redox Biology 19 (octobre 2018) : 116–33. http://dx.doi.org/10.1016/j.redox.2018.08.006.

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Jakimowicz, Dagmara, Sebastien Mouz, Jolanta Zakrzewska-Czerwińska et Keith F. Chater. « Developmental Control of a parAB Promoter Leads to Formation of Sporulation-Associated ParB Complexes in Streptomyces coelicolor ». Journal of Bacteriology 188, no 5 (1 mars 2006) : 1710–20. http://dx.doi.org/10.1128/jb.188.5.1710-1720.2006.

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ABSTRACT The Streptomyces coelicolor partitioning protein ParB binds to numerous parS sites in the oriC-proximal part of the linear chromosome. ParB binding results in the formation of large complexes, which behave differentially during the complex life cycle (D. Jakimowicz, B. Gust, J. Zakrzewska-Czerwinska, and K. F. Chater, J. Bacteriol. 187:3572-3580, 2005). Here we have analyzed the transcriptional regulation that underpins this developmentally specific behavior. Analysis of promoter mutations showed that the irregularly spaced complexes present in vegetative hyphae are dependent on the constitutive parABp 1 promoter, while sporulation-specific induction of the promoter parABp 2 is required for the assembly of arrays of ParB complexes in aerial hyphae and thus is necessary for efficient chromosome segregation. Expression from parABp 2 depended absolutely on two sporulation regulatory genes, whiA and whiB, and partially on two others, whiH and whiI, all four of which are needed for sporulation septation. Because of this pattern of dependence, we investigated the transcription of these four whi genes in whiA and whiB mutants, revealing significant regulatory interplay between whiA and whiB. A strain in which sporulation septation (but not vegetative septation) was blocked by mutation of a sporulation-specific promoter of ftsZ showed close to wild-type induction of parABp 2 and formed fairly regular ParB-enhanced green fluorescent protein foci in aerial hyphae, ruling out strong morphological coupling or checkpoint regulation between septation and DNA partitioning during sporulation. A model for developmental regulation of parABp 2 expression is presented.
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Smith, Laura J., Melanie R. Stapleton, Roger S. Buxton et Jeffrey Green. « Structure-Function Relationships of the Mycobacterium tuberculosis Transcription Factor WhiB1 ». PLoS ONE 7, no 7 (5 juillet 2012) : e40407. http://dx.doi.org/10.1371/journal.pone.0040407.

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Stapleton, Melanie R., Laura J. Smith, Debbie M. Hunt, Roger S. Buxton et Jeffrey Green. « Mycobacterium tuberculosis WhiB1 represses transcription of the essential chaperonin GroEL2 ». Tuberculosis 92, no 4 (juillet 2012) : 328–32. http://dx.doi.org/10.1016/j.tube.2012.03.001.

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Parikh, Pankti, Manbeena Chawla, Kyle Minch, Tige Rustad, David Sherman et Amit Singh. « Mycobacterium Tuberculosis WhiB4 is a Redox – Dependent Nucleoid Associated Protein ». Free Radical Biology and Medicine 53 (novembre 2012) : S34—S35. http://dx.doi.org/10.1016/j.freeradbiomed.2012.10.088.

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Fowler-Goldsworthy, Kay, Bertolt Gust, Sébastien Mouz, Govind Chandra, Kim C. Findlay et Keith F. Chater. « The actinobacteria-specific gene wblA controls major developmental transitions in Streptomyces coelicolor A3(2) ». Microbiology 157, no 5 (1 mai 2011) : 1312–28. http://dx.doi.org/10.1099/mic.0.047555-0.

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The Streptomyces coelicolor A3(2) sporulation gene whiB is the paradigm of a family of genes (wbl, whiB- like) that are confined to actinobacteria. The chromosome of S. coelicolor contains 11 wbl genes, among which five are conserved in many actinobacteria: whiB itself; whiD, a sporulation gene; wblC, which is required for multi-drug resistance; and wblA and wblE, whose roles had previously been little studied. We succeeded in disrupting wblA and the six non-conserved genes, but could not disrupt wblE. Although mutations in the six non-conserved wbl genes (including some multiple wbl mutants) produced no readily detectable phenotype, mutations in wblA had novel and complex effects. The aerial mycelium of wblA mutants was coloured red, because of the ectopic presence of pigmented antibiotics (actinorhodin and undecylprodigiosin) normally confined to lower parts of wild-type colonies, and consisted almost entirely of non-sporulating, thin, straight filaments, often bundled together in a fibrillar matrix. Rare spore chains were also formed, which exhibited wild-type properties but were genetically still wblA mutants. A wblA mutant achieved higher biomass than the wild-type. Microarray analysis indicated major transcriptional changes in a wblA mutant: using a relatively stringent cut-off, 183 genes were overexpressed, including genes for assimilative primary metabolism and actinorhodin biosynthesis, and 103 were underexpressed, including genes associated with stages of aerial hyphal growth. We suggest that WblA is important in both the slow-down of biomass accumulation and the change from aerial hyphal initial cells to the subapical stem and apical compartments that precede sporulation; and that the mutant aerial mycelium consists of recapitulated defective aerial hyphal initial cells.
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Bush, Matthew J. « The actinobacterial WhiB-like (Wbl) family of transcription factors ». Molecular Microbiology 110, no 5 (25 octobre 2018) : 663–76. http://dx.doi.org/10.1111/mmi.14117.

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Garg, Saurabh K., Md Suhail Alam, Vishal Soni, K. V. Radha Kishan et Pushpa Agrawal. « Characterization of Mycobacterium tuberculosis WhiB1/Rv3219 as a protein disulfide reductase ». Protein Expression and Purification 52, no 2 (avril 2007) : 422–32. http://dx.doi.org/10.1016/j.pep.2006.10.015.

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BOISSIN, Jean-Pierre, Jean-Claude CASTAGNOS et Gilles GUIEU. « L'influence de la pensée de James March sur la recherche francophone en management stratégique : une analyse bibliométrique ». Management international 9, no 4 (2005) : 65–76. http://dx.doi.org/10.59876/a-k515-whb6.

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This article analyzes James March's influence on strategic thought in the last decade by locating, in bibliographies of recent works on strategy, explicit references to March, then by analyzing, within the same articles and papers, the "citation context." This examination shows a significant presence of March in the bibliographies of the beginning of the decade (presence in 10% of the articles, mainly dealing with strategic processes) and increased importance between 1998 and 2000 (21% of the papers and articles). The works of March essentially add input to lines of research on management tools and on the themes of learning, cognition, leaders, and innovation. The additional analysis of the co-citations of the authors reveal five axes in the use of March's thinking: organizational, psychological, economic, evolutionist, and sociological. Each of these readings involves a distinctive definition of strategy: product of decision-making, mental creation, economic phenomenon, product and driving force of a dynamic evolution, or outcome of a behaviour.
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Molloy, Sally, Jaycee Cushman, Emma Freeman et Keith Hutchison. « Prophage BPs Alters Mycobacterial Gene Expression and Antibiotic Resistance ». Proceedings 50, no 1 (16 juin 2020) : 67. http://dx.doi.org/10.3390/proceedings2020050067.

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Diseases caused by mycobacteria such as Mycobacterium tuberculosis are the leading cause of death worldwide. With the emergence of strains that are resistant to first-line anti-tuberculosis drugs and naturally drug-resistant pathogens such as M. abscessus, there is a need to increase our understanding of mycobacterial fitness and virulence and identify new targets for drugs. The majority of the pathogenic species of the bacterial genus Mycobacterium, including M. tuberculosis, carry integrated viral genomes (prophages) that are hypothesized to contribute to virulence. Though we know many of the ways in which phage genes directly contribute to pathogenesis, e.g., the CTX prophage encodes the toxin in Vibrio cholera, we know little about the impact of phages that encode no obvious toxin or virulence gene. Using an RNAseq approach, our lab recently showed for the first time that the presence of a prophage alters the expression of 7.4% of genes in the pathogenic mycobacterial species, M. chelonae. The presence of prophage BPs increased the expression of genes in the whiB7 regulon, including whiB7, eis2, and tap, and decreased the expression of a padR-family transcription factor. BP lysogens were more resistant to aminoglycosides (kanamycin and amikacin) and tetracycline than wild-type strains of M. chelonae. In order to determine how the BP prophage drives changes in bacterial gene expression and phenotype, we will test the effects of individual BP genes expressed during lysogeny, such as the immunity repressor, on bacterial gene expression and antibiotic resistance phenotypes.
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Duan, Wei, Xue Li, Yan Ge, Zhaoxiao Yu, Ping Li, Jiang Li, Lianhua Qin et Jianping Xie. « Mycobacterium tuberculosisRv1473 is a novel macrolides ABC Efflux Pump regulated by WhiB7 ». Future Microbiology 14, no 1 (janvier 2019) : 47–59. http://dx.doi.org/10.2217/fmb-2018-0207.

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Warit, Saradee, Saranya Phunpruch, Chaitas Jityam, Sarinya Jaitrong, Pamaree Billamas, Angkana Chaiprasert, Prasit Palittapongarnpim et Therdsak Prammananan. « Genetic characterisation of a whiB7 mutant of a Mycobacterium tuberculosis clinical strain ». Journal of Global Antimicrobial Resistance 3, no 4 (décembre 2015) : 262–66. http://dx.doi.org/10.1016/j.jgar.2015.07.004.

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Kang, Seung-Hoon, Jianqiang Huang, Han-Na Lee, Yoon-Ah Hur, Stanley N. Cohen et Eung-Soo Kim. « Interspecies DNA Microarray Analysis Identifies WblA as a Pleiotropic Down-Regulator of Antibiotic Biosynthesis in Streptomyces ». Journal of Bacteriology 189, no 11 (6 avril 2007) : 4315–19. http://dx.doi.org/10.1128/jb.01789-06.

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ABSTRACT Using Streptomyces coelicolor microarrays to discover regulators of gene expression in other Streptomyces species, we identified wblA, a whiB-like gene encoding a putative transcription factor, as a down-regulator of doxorubicin biosynthesis in Streptomyces peucetius. Further analysis revealed that wblA functions pleiotropically to control antibiotic production and morphological differentiation in streptomycetes. Our results reveal a novel biological role for wblA and show the utility of interspecies microarray analysis for the investigation of streptomycete gene expression.
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Lee, Ju‐Hyung, Eun‐Jin Lee et Jung‐Hye Roe. « uORF‐mediated riboregulation controls transcription of whiB7/wblC antibiotic resistance gene ». Molecular Microbiology 117, no 1 (2 novembre 2021) : 179–92. http://dx.doi.org/10.1111/mmi.14834.

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Larsson, Christer, Brian Luna, Nicole C. Ammerman, Mamoudou Maiga, Nisheeth Agarwal et William R. Bishai. « Gene Expression of Mycobacterium tuberculosis Putative Transcription Factors whiB1-7 in Redox Environments ». PLoS ONE 7, no 7 (19 juillet 2012) : e37516. http://dx.doi.org/10.1371/journal.pone.0037516.

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Suhail Alam, Md, et Pushpa Agrawal. « Matrix-assisted refolding and redox properties of WhiB3/Rv3416 of Mycobacterium tuberculosis H37Rv ». Protein Expression and Purification 61, no 1 (septembre 2008) : 83–91. http://dx.doi.org/10.1016/j.pep.2008.04.010.

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Hutter, Bernd, et Thomas Dick. « Molecular genetic characterisation of whiB3, a mycobacterial homologue of a Streptomyces sporulation factor ». Research in Microbiology 150, no 5 (juin 1999) : 295–301. http://dx.doi.org/10.1016/s0923-2508(99)80055-2.

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Burian, Ján, Santiago Ramón-García, Charles G. Howes et Charles J. Thompson. « WhiB7, a transcriptional activator that coordinates physiology with intrinsic drug resistance inMycobacterium tuberculosis ». Expert Review of Anti-infective Therapy 10, no 9 (septembre 2012) : 1037–47. http://dx.doi.org/10.1586/eri.12.90.

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Mulder, N. J., H. Zappe et L. M. Steyn. « Characterization of a Mycobacterium tuberculosis homologue of the Streptomyces coelicolor whiB gene ». Tubercle and Lung Disease 79, no 5 (septembre 1999) : 299–308. http://dx.doi.org/10.1054/tuld.1999.0217.

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Averina, Olga V., Natalia V. Zakharevich et Valery N. Danilenko. « Identification and characterization of WhiB-like family proteins of the Bifidobacterium genus ». Anaerobe 18, no 4 (août 2012) : 421–29. http://dx.doi.org/10.1016/j.anaerobe.2012.04.011.

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Chawla, Manbeena, Pankti Parikh, Alka Saxena, MohamedHusen Munshi, Mansi Mehta, Deborah Mai, Anup K. Srivastava et al. « Mycobacterium tuberculosis WhiB4 regulates oxidative stress response to modulate survival and dissemination in vivo ». Molecular Microbiology 85, no 6 (26 juillet 2012) : 1148–65. http://dx.doi.org/10.1111/j.1365-2958.2012.08165.x.

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Vatlin, Aleksey A., Olga B. Bekker, Kirill V. Shur, Rustem A. Ilyasov, Petr A. Shatrov, Dmitry A. Maslov et Valery N. Danilenko. « Kanamycin and Ofloxacin Activate the Intrinsic Resistance to Multiple Antibiotics in Mycobacterium smegmatis ». Biology 12, no 4 (27 mars 2023) : 506. http://dx.doi.org/10.3390/biology12040506.

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Drug resistance (DR) in Mycobacterium tuberculosis is the main problem in fighting tuberculosis (TB). This pathogenic bacterium has several types of DR implementation: acquired and intrinsic DR. Recent studies have shown that exposure to various antibiotics activates multiple genes, including genes responsible for intrinsic DR. To date, there is evidence of the acquisition of resistance at concentrations well below the standard MICs. In this study, we aimed to investigate the mechanism of intrinsic drug cross-resistance induction by subinhibitory concentrations of antibiotics. We showed that pretreatment of M. smegmatis with low doses of antibiotics (kanamycin and ofloxacin) induced drug resistance. This effect may be caused by a change in the expression of transcriptional regulators of the mycobacterial resistome, in particular the main transcriptional regulator whiB7.
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45

Lilic, Mirjana, Seth A. Darst et Elizabeth A. Campbell. « Structural basis of transcriptional activation by the Mycobacterium tuberculosis intrinsic antibiotic-resistance transcription factor WhiB7 ». Molecular Cell 81, no 14 (juillet 2021) : 2875–86. http://dx.doi.org/10.1016/j.molcel.2021.05.017.

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Saini, Vikram, Aisha Farhana et Adrie J. C. Steyn. « Mycobacterium tuberculosis WhiB3 : A Novel Iron–Sulfur Cluster Protein That Regulates Redox Homeostasis and Virulence ». Antioxidants & ; Redox Signaling 16, no 7 (avril 2012) : 687–97. http://dx.doi.org/10.1089/ars.2011.4341.

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Singh, Amit, David K. Crossman, Deborah Mai, Loni Guidry, Martin I. Voskuil, Matthew B. Renfrow et Adrie J. C. Steyn. « Mycobacterium tuberculosis WhiB3 Maintains Redox Homeostasis by Regulating Virulence Lipid Anabolism to Modulate Macrophage Response ». PLoS Pathogens 5, no 8 (14 août 2009) : e1000545. http://dx.doi.org/10.1371/journal.ppat.1000545.

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Wan, Tao, Magdaléna Horová, Daisy Guiza Beltran, Shanren Li, Huey-Xian Wong et Li-Mei Zhang. « Structural insights into the functional divergence of WhiB-like proteins in Mycobacterium tuberculosis ». Molecular Cell 81, no 14 (juillet 2021) : 2887–900. http://dx.doi.org/10.1016/j.molcel.2021.06.002.

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Ryding, N. Jamie, Maureen J. Bibb, Virginie Molle, Kim C. Findlay, Keith F. Chater et Mark J. Buttner. « New Sporulation Loci in Streptomyces coelicolor A3(2) ». Journal of Bacteriology 181, no 17 (1 septembre 1999) : 5419–25. http://dx.doi.org/10.1128/jb.181.17.5419-5425.1999.

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ABSTRACT Sporulation mutants of Streptomyces coelicolor appear white because they are defective in the synthesis of the grey polyketide spore pigment, and such white (whi) mutants had been used to define eight sporulation loci, whiA,whiB, whiD, whiE, whiG,whiH, whiI, and whiJ (K. F. Chater, J. Gen. Microbiol. 72:9–28, 1972; N. J. Ryding, Ph.D. thesis, University of East Anglia, 1995). In an attempt to identify new whi loci, we mutagenized S. coelicolor M145 spores with nitrosoguanidine and identified 770 mutants with colonies ranging from white to medium grey. After excluding unstable strains, we examined the isolates by phase-contrast microscopy and chose 115 whi mutants with clear morphological phenotypes for further study. To exclude mutants representing cloned whi genes, self-transmissible SCP2*-derived plasmids carrying whiA, whiB,whiG, whiH, or whiJ (but notwhiD, whiE, or whiI) were introduced into each mutant by conjugation, and strains in which the wild-type phenotype was restored either partially or completely by any of these plasmids were excluded from further analysis. In an attempt to complement some of the remaining 31 whi mutants, an SCP2* library of wild-type S. coelicolor chromosomal DNA was introduced into 19 of the mutants by conjugation. Clones restoring the wild-type phenotype to 12 of the 19 strains were isolated and found to represent five distinct loci, designated whiK,whiL, whiM, whiN, andwhiO. Each of the five loci was located on the ordered cosmid library: whiL, whiM, whiN, and whiO occupied positions distinct from previously clonedwhi genes; whiK was located on the same cosmid overlap as whiD, but the two loci were shown by complementation to be distinct. The phenotypes resulting from mutations at each of these new loci are described.
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Molle, Virginie, Wendy J. Palframan, Kim C. Findlay et Mark J. Buttner. « WhiD and WhiB, Homologous Proteins Required for Different Stages of Sporulation in Streptomyces coelicolor A3(2) ». Journal of Bacteriology 182, no 5 (1 mars 2000) : 1286–95. http://dx.doi.org/10.1128/jb.182.5.1286-1295.2000.

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ABSTRACT The whiD locus, which is required for the differentiation of Streptomyces coelicolor aerial hyphae into mature spore chains, was localized by map-based cloning to the overlap between cosmids 6G4 and D63 of the minimal ordered library of Redenbach et al. (M. Redenbach et al., Mol. Microbiol. 21:77–96, 1996). Subcloning and sequencing showed that whiD encodes a homologue of WhiB, a protein required for the initiation of sporulation septation in S. coelicolor. WhiD and WhiB belong to a growing family of small (76- to 112-residue) proteins of unknown biochemical function in which four cysteines are absolutely conserved; all known members of this family are found in the actinomycetes. A constructed whiD null mutant showed reduced levels of sporulation, and those spores that did form were heat sensitive, lysed extensively, and were highly irregular in size, arising at least in part from irregularity in septum placement. The whiD null mutant showed extreme variation in spore cell wall deposition; most spores had uniformly thin (20- to 30-nm) walls, but spore chains were frequently observed in which there was irregular but very pronounced (up to 170 nm) cell wall thickening at the junctions between spores.whiD null mutant spores were frequently partitioned into irregular smaller units through the deposition of additional septa, which were often laid down in several different planes, very close to the spore poles. These “minicompartments” appeared to be devoid of chromosomal DNA. Two whiD promoters, whiDp1 andwhiDp2, were identified, and their activities were analyzed during development of wild-type S. coelicolor on solid medium. Both promoters were developmentally regulated;whiDp1 and whiDp2 transcripts were detected transiently, approximately at the time when sporulation septa were observed in the aerial hyphae.
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