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Artykuły w czasopismach na temat "M. tuberculosis ArgJ"
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Pasula, Rajamouli, Paul Wisniowski i William J. Martin. "Fibronectin Facilitates Mycobacterium tuberculosis Attachment to Murine Alveolar Macrophages". Infection and Immunity 70, nr 3 (marzec 2002): 1287–92. http://dx.doi.org/10.1128/iai.70.3.1287-1292.2002.
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ABSTRACT Mycobacterium tuberculosis remains a major cause of pulmonary infection worldwide. Attachment of M. tuberculosis organisms to alveolar macrophages (AMs) represents the earliest phase of primary infection in pulmonary tuberculosis. In this study fibronectin (Fn), an adhesive protein, is shown to bind M. tuberculosis organisms and facilitates attachment of M. tuberculosis to murine AMs. A monoclonal antibody (MAb) specific to the heparin binding domain (HBD) of Fn decreases 125I-Fn binding to M. tuberculosis; whereas MAbs specific to either the cell binding domain (CBD) or the gelatin binding domain (GBD) have no effect on Fn binding to M. tuberculosis. In the presence of exogenous Fn (10 μg/ml) M. tuberculosis attachment to AMs increased significantly from control levels (means ± standard errors of the means) of 11.5% ± 1.1% to 44.2% ± 4.2% (P < 0.05). Fn-enhanced attachment was significantly decreased from 44.2% ± 4.2% to 10.8% ± 1.2% (P < 0.05) in the presence of anti-Fn polyclonal antibodies. The attachment is also inhibited in the presence of MAbs specific for the HBD and CBD, whereas MAbs specific to GBD did not affect the attachment. Further, an Fn cell binding peptide, Arg-Gly-Asp-Ser (RGDS), decreased the attachment from 44.2% ± 4.2% to 15.3% ± 1.2% (P < 0.05), whereas addition of a control peptide, Arg-Gly-Glu-Ser (RGES) did not affect the attachment (40.5% ± 1.8%). These results suggest that Fn-mediated attachment of M. tuberculosis can occur through the binding of Fn to the AM via the CBD and to M. tuberculosis organisms via the HBD.
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Qualls, Joseph E., Ashley DeFreitas, Amber M. Smith, Stephanie S. Watowich i Peter J. Murray. "Direct and indirect type-1 arginase (Arg1) induction following Mycobacterium bovis (BCG) infection (43.1)". Journal of Immunology 182, nr 1_Supplement (1.04.2009): 43.1. http://dx.doi.org/10.4049/jimmunol.182.supp.43.1.
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Abstract M. tuberculosis infects lung macrophages (MØs) and evades immune responses by a diverse array of mechanisms. We have recently published that BCG infection triggers a MyD88-dependent Arg1 induction that suppresses NO production from infected MØs. In addition, MØ-specific Arg1 conditional knockout mice were more efficient at clearing M. tuberculosis and BCG. In the present study, we have found that while MyD88 is essential for Arg1 induction following infection, MyD88-/- MØs express robust Arg1 mRNA and protein when stimulated with supernatant from BCG-infected WT MØs. Arg1 induction stimulated with BCG supernatant correlated with enhanced activation of Stat3, but not Stat1, 4, 5, or 6. Two Stat3 activators, IL-6 and IL-10, were present in the supernatants of BCG infected WT MØs. We found the combined treatment of MØs with IL-6 and IL-10 synergistically induces Arg1 in the presence or absence of BCG infection. Consequently, we propose a model by which Arg1 is induced directly by BCG infection via MyD88 signaling, and indirectly through the autocrine/paracrine IL-6/IL-10 activation of Stat3. These data suggest that mycobacteria can condition uninfected neighboring cells to suppress NO production.
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Walter, Nicholas D., Bouke C. de Jong, Benjamin J. Garcia, Gregory M. Dolganov, William Worodria, Patrick Byanyima, Emmanuel Musisi i in. "Adaptation of Mycobacterium tuberculosis to Impaired Host Immunity in HIV-Infected Patients". Journal of Infectious Diseases 214, nr 8 (17.08.2016): 1205–11. http://dx.doi.org/10.1093/infdis/jiw364.
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AbstractBackground. It is unknown whether immunosuppression influences the physiologic state of Mycobacterium tuberculosis in vivo. We evaluated the impact of host immunity by comparing M. tuberculosis and human gene transcription in sputum between human immunodeficiency virus (HIV)–infected and uninfected patients with tuberculosis.Methods. We collected sputum specimens before treatment from Gambians and Ugandans with pulmonary tuberculosis, revealed by positive results of acid-fast bacillus smears. We quantified expression of 2179 M. tuberculosis genes and 234 human immune genes via quantitative reverse transcription–polymerase chain reaction. We summarized genes from key functional categories with significantly increased or decreased expression.Results. A total of 24 of 65 patients with tuberculosis were HIV infected. M. tuberculosis DosR regulon genes were less highly expressed among HIV-infected patients with tuberculosis than among HIV-uninfected patients with tuberculosis (Gambia, P < .0001; Uganda, P = .037). In profiling of human genes from the same sputa, HIV-infected patients had 3.4-fold lower expression of IFNG (P = .005), 4.9-fold higher expression of ARG1 (P = .0006), and 3.4-fold higher expression of IL10 (P = .0002) than in HIV-uninfected patients with tuberculosis.Conclusions. M. tuberculosis in HIV-infected patients had lower expression of the DosR regulon, a critical metabolic and immunomodulatory switch induced by NO, carbon monoxide, and hypoxia. Our human data suggest that decreased DosR expression may result from alternative pathway activation of macrophages, with consequent decreased NO expression and/or by poor granuloma formation with consequent decreased hypoxic stress.
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Errey, James C., i John S. Blanchard. "Functional Characterization of a Novel ArgA from Mycobacterium tuberculosis". Journal of Bacteriology 187, nr 9 (1.05.2005): 3039–44. http://dx.doi.org/10.1128/jb.187.9.3039-3044.2005.
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ABSTRACT The Mycobacterium tuberculosis gene Rv2747 encodes a novel 19-kDa ArgA that catalyzes the initial step in l-arginine biosynthesis, namely the conversion of l-glutamate to α-N-acetyl-l-glutamate. Initial velocity studies reveal that Rv2747 proceeds through a sequential kinetic mechanism, with Km values of 280 mM for l-glutamine and 150 μM for acetyl-coenzyme A and with a k cat value of 200 min−1. Initial velocity studies with l-glutamate showed that even at concentrations of 600 mM, saturation was not observed. Therefore, only a k cat/Km value of 125 M−1 min−1 can be calculated. Inhibition studies reveal that the enzyme is strongly regulated by l-arginine, the end product of the pathway (50% inhibitory concentration, 26 μM). The enzyme was completely inhibited by 500 μM arginine, with a Hill coefficient of 0.60, indicating negatively cooperative binding of l-arginine.
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Napolitano, Danielle R., Nira Pollock, Suely S. Kashino, Virmondes Rodrigues i Antonio Campos-Neto. "Identification of Mycobacterium tuberculosis Ornithine Carboamyltransferase in Urine as a Possible Molecular Marker of Active Pulmonary Tuberculosis". Clinical and Vaccine Immunology 15, nr 4 (27.02.2008): 638–43. http://dx.doi.org/10.1128/cvi.00010-08.
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ABSTRACT Although the antigen detection assay has the potential to discriminate active tuberculosis from latent infection, development of such a test for the accurate diagnosis of this serious disease has only recently become a matter of interest. Here we present evidence that a Mycobacterium tuberculosis protein (ornithine carboamyltransferase, coded for by MT_1694; Rv1656 [argF]) is an interesting candidate molecule for this test development. The protein was initially discovered by mass spectroscopy in urine of patients with pulmonary tuberculosis and shown by Western blot analysis to be present in M. tuberculosis crude cell extract as well as in the culture supernatant (“secreted” protein). In addition, a recombinant ornithine carboamyltransferase (rMT1694) produced in Escherichia coli was recognized by immunoglobulin G (IgG) antibodies from patients with active tuberculosis but not by IgG from uninfected healthy subjects. Moreover, rMT1694 was strongly recognized by peripheral blood mononuclear cells from both healthy tuberculin purified protein derivative (PPD)-positive individuals and patients with pulmonary tuberculosis. More importantly, a capture enzyme-linked immunosorbent assay formatted with rabbit IgG antibodies specific to rMT1694 was able to identify the presence of this antigen in urine samples from 6 of 16 patients with pulmonary tuberculosis and in none of 16 urine samples collected from healthy PPD+ controls. These results indicate that an improved antigen detection assay based on M. tuberculosis ornithine carboamyltransferase may represent an important new strategy for the development of a specific and accurate diagnostic test for tuberculosis.
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Bashiri, Ghader, Laura V. Nigon, Ehab N. M. Jirgis, Ngoc Anh Thu Ho, Tamsyn Stanborough, Stephanie S. Dawes, Edward N. Baker, Esther M. M. Bulloch i Jodie M. Johnston. "Allosteric regulation of menaquinone (vitamin K2) biosynthesis in the human pathogen Mycobacterium tuberculosis". Journal of Biological Chemistry 295, nr 12 (6.02.2020): 3759–70. http://dx.doi.org/10.1074/jbc.ra119.012158.
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Menaquinone (vitamin K2) plays a vital role in energy generation and environmental adaptation in many bacteria, including the human pathogen Mycobacterium tuberculosis (Mtb). Although menaquinone levels are known to be tightly linked to the cellular redox/energy status of the cell, the regulatory mechanisms underpinning this phenomenon are unclear. The first committed step in menaquinone biosynthesis is catalyzed by MenD, a thiamine diphosphate–dependent enzyme comprising three domains. Domains I and III form the MenD active site, but no function has yet been ascribed to domain II. Here, we show that the last cytosolic metabolite in the menaquinone biosynthesis pathway, 1,4-dihydroxy-2-naphthoic acid (DHNA), binds to domain II of Mtb-MenD and inhibits its activity. Using X-ray crystallography of four apo- and cofactor-bound Mtb-MenD structures, along with several spectroscopy assays, we identified three arginine residues (Arg-97, Arg-277, and Arg-303) that are important for both enzyme activity and the feedback inhibition by DHNA. Among these residues, Arg-277 appeared to be particularly important for signal propagation from the allosteric site to the active site. This is the first evidence of feedback regulation of the menaquinone biosynthesis pathway in bacteria, identifying a protein-level regulatory mechanism that controls menaquinone levels within the cell and may therefore represent a good target for disrupting menaquinone biosynthesis in M. tuberculosis.
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Nagel, Raimund, Jill Thomas, Faith Adekunle, Francis Mann i Reuben Peters. "Arginine in the FARM and SARM: A Role in Chain-Length Determination for Arginine in the Aspartate-Rich Motifs of Isoprenyl Diphosphate Synthases from Mycobacterium tuberculosis". Molecules 23, nr 10 (6.10.2018): 2546. http://dx.doi.org/10.3390/molecules23102546.
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Isoprenyl chains are found in many important metabolites. These are derived from precursors of the appropriate length produced by isoprenyl diphosphate synthases (IDSs). The human pathogen Mycobacterium tuberculosis makes various isoprenoids/terpenoids, with important roles in their biosynthesis played by two closely related IDSs, encoded by grcC1 (Rv0562) and grcC2 (Rv0989c), with Rv0989c generating the 10-carbon precursor (E)-geranyl diphosphate (GPP), and Rv0562 the 20-carbon precursor (E,E,E)-geranylgeranyl diphosphate (GGPP). Intriguingly, while Rv0562 contains the prototypical trans-IDS first and second aspartate-rich (DDxxD) motifs (FARM and SARM, respectively), Rv0989c uniquely contains arginine in place of the second Asp in the FARM and first Asp in the SARM. Here site-directed mutagenesis of the corresponding residues in both Rv0562 and Rv0989c reveals that these play a role in determination of product chain length. Specifically, substitution of Asp for the Arg in the FARM and SARM of Rv0989c leads to increased production of the longer 15-carbon farnesyl diphosphate (FPP), while substitution of Arg for the corresponding Asp in Rv0562 leads to increased release of shorter products, both FPP and GPP. Accordingly, while the primary role of the FARM and SARM is known to be chelation of the divalent magnesium ion co-factors that assist substrate binding and catalysis, the Arg substitutions found in Rv0989c seem to provide a novel means by which product chain length is moderated, at least in these M. tuberculosis IDSs.
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Billington, O. J., T. D. McHugh i S. H. Gillespie. "Physiological Cost of Rifampin Resistance Induced In Vitro in Mycobacterium tuberculosis". Antimicrobial Agents and Chemotherapy 43, nr 8 (1.08.1999): 1866–69. http://dx.doi.org/10.1128/aac.43.8.1866.
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ABSTRACT Drug-resistant Mycobacterium tuberculosis is a major threat to public health. In clinical practice, a limited number of resistance mutations in a short sequence of the beta subunit of RNA polymerase (encoded by rpoB) have been described. Spontaneous resistance to rifampin was induced in vitro in M. tuberculosis H37Rv (ATCC 9360). Only three resistance patterns could be detected by PCR–single-strand conformation polymorphism analysis. Sequence analysis revealed that Ser531→Leu arose most frequently, followed by His526→Arg and then either His526→Tyr or His526→Asp. The relative Darwinian fitness of all but one of the mutant genotypes was less than that of the susceptible parent and, for these mutations, there was a significant correlation between fitness and clinical isolation rate (regression analysis P = 0.026). The fitness deficit in some mutants was small, suggesting that there is little likelihood of a spontaneous reversion to susceptibility.
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Gao, Lian-Yong, Melissa Pak, Rabab Kish, Kimberly Kajihara i Eric J. Brown. "A Mycobacterial Operon Essential for Virulence In Vivo and Invasion and Intracellular Persistence in Macrophages". Infection and Immunity 74, nr 3 (marzec 2006): 1757–67. http://dx.doi.org/10.1128/iai.74.3.1757-1767.2006.
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ABSTRACT The ability to invade and grow in macrophages is necessary for Mycobacterium tuberculosis to cause disease. We have found a Mycobacterium marinum locus of two genes that is required for both invasion and intracellular survival in macrophages. The genes were designated iipA (mycobacterial invasion and intracellular persistence) and iipB. The iip mutant, which was created by insertion of a kanamycin resistance gene cassette at the 5′ region of iipA, was completely avirulent to zebra fish. Expression of the M. tuberculosis orthologue of iipA, Rv1477, fully complemented the iip mutant for infectivity in vivo, as well as for invasion and intracellular persistence in macrophages. In contrast, the iipB orthologue, Rv1478, only partially complemented the iip mutant in vivo and restored invasion but not intracellular growth in macrophages. While IipA and IipB differ at their N termini, they are highly similar throughout their C-terminal NLPC_p60 domains. The p60 domain of Rv1478 is fully functional to replace that of Rv1477, suggesting that the N-terminal sequence of Rv1477 is required for full virulence in vivo and in macrophages. Further mutations demonstrated that both Arg-Gly-Asp (RGD) and Asp-Cys-Ser-Gly (DCSG) sequences in the p60 domain are required for function. The iip mutant exhibited increased susceptibility to antibiotics and lysozyme and failed to fully separate daughter cells in liquid culture, suggesting a role for iip genes in cell wall structure and function. Altogether, these studies demonstrate an essential role for a p60-containing protein, IipA, in the pathogenesis of M. marinum infection.
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Guillemin, Isabelle, Vincent Jarlier i Emmanuelle Cambau. "Correlation between Quinolone Susceptibility Patterns and Sequences in the A and B Subunits of DNA Gyrase in Mycobacteria". Antimicrobial Agents and Chemotherapy 42, nr 8 (1.08.1998): 2084–88. http://dx.doi.org/10.1128/aac.42.8.2084.
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ABSTRACT The in vitro activities of seven quinolones and the sequences of the quinolone resistance-determining regions (QRDR) in the A and B subunits of DNA gyrase were determined for 14 mycobacterial species. On the basis of quinolone activity, quinolones were arranged from that with the greatest to that with the least activity as follows: sparfloxacin, levofloxacin, ciprofloxacin, ofloxacin, pefloxacin, flumequine, and nalidixic acid. Based on MICs, the species could be organized into three groups: resistant (Mycobacterium avium, M. intracellulare, M. marinum,M. chelonae, M. abscessus [ofloxacin MICs, ≥8 μg/ml]), moderately susceptible (M. tuberculosis,M. bovis BCG, M. kansasii, M. leprae, M. fortuitum third biovariant, M. smegmatis [ofloxacin MICs, 0.5 to 1 μg/ml]), and susceptible (M. fortuitum, M. peregrinum, M. aurum [ofloxacin MICs, ≤0.25 μg/ml]). Peptide sequences of the QRDR of GyrB were identical in all the species, including the amino acids at the three positions known to be involved in acquired resistance to quinolone, i.e., 426 (Asp), 447 (Arg), and 464 (Asn) (numbering system used for Escherichia coli). The last two residues could be involved in the overall low level of susceptibility of mycobacteria to quinolones since they differ from those found in the very susceptible E. coli (Lys-447 and Ser-464) but are identical to those found in the less susceptible Staphylococcus aureus and Streptococcus pneumoniae. Peptide sequences of the QRDR of GyrA were identical in all the species, except for the amino acid at position 83, which was an alanine in the two less susceptible groups and a serine in the most susceptible one, as inE. coli, suggesting that this amino acid is involved in the observed differences of quinolone susceptibility within theMycobacterium genus.