Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small heat shock proteins (sHSPs) are highly divergent in primary sequences, with short conserved motifs found in various subfamilies. Here a Pro-Gly doublet was found to be conserved in most non-animal sHSPs by sequence analysis of a total of 344 unique sHSPs (covering the subfamilies: bacterial class A, bacterial class B, archae, fungi, plant, and animal) placed in data banks. In contrast, the residues corresponding to this Pro-Gly doublet in most of animal sHSPs are often charged. Site-directed mutagenesis studies of Mycobacterium tuberculosis Hsp16.3 replacing the Gly (at position 59) residue by Cys or Trp demonstrate that this Gly is likely involved in subunit interactions, which is consistent with that in Methanococcus jannaschii Hsp16.5 and wheat Hsp16.9. Our data suggest that this Pro-Gly doublet in Hsp16.3 is not directly involved in binding of denatured substrate proteins, whereas the corresponding charged residues in bovine alpha-crystallin were instead proposed before to be involved in substrate binding. These observations indicate that the highly conserved Pro-Gly doublet is critical to discriminate between non-animal and animal sHSPs.
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PMID:Identification of a highly conserved pro-gly doublet in non-animal small heat shock proteins and characterization of its structural and functional roles in Mycobacterium tuberculosis Hsp16.3. 1648 74

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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PMID:A mycobacterial operon essential for virulence in vivo and invasion and intracellular persistence in macrophages. 1649 49

Missense alterations in genes mutT4 and mutT2, which encode DNA repair enzymes, were sequenced from 30 clinical isolates of Mycobacterium tuberculosis of Beijing genotype, mostly from patients with primary tuberculosis, to evaluate their contribution to anti-mycobacterial drug resistance. The mutation Arg to Gly at codon position 48 (CGG to GGG) of mutT4 was found in 21 isolates; of these, 16 isolates also harboured the mutation Gly to Arg at position 58 (GGA to CGA) of mutT2. No statistically significant association was found between mutT4 and mutT2 mutations, and drug resistance. Furthermore, no mutations in mutT4 or mutT2 were found in any of 24 isolates resistant to multiple drugs, nor in 28 anti-mycobacterial drug-susceptible isolates of different genotypes. These data confirm that the polymorphism of mutT genes is characteristic and unique to the Beijing phylogenetic lineage. The mutator phenotype does not appear to increase prevalence of drug resistance, but further studies are required to investigate the mutation rates of Beijing isolates in response to drug exposure.
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PMID:Mutations in mutT genes of Mycobacterium tuberculosis isolates of Beijing genotype. 1658 48

Here we report a novel domain, MSTF (domain involved in bacterial metallopeptidases, surface proteins and other proteins, also present in mycobacteriophage tape-measure proteins and fungal proteins), which is present in bacteria, phages and fungi. MSTF is about 67-94 amino acids in length with one HxDHxH motif and some highly conserved residues including His, Gly, Ala and Asp. Secondary structure prediction indicated that this domain contains two alpha-helices and one beta-sheet. Identification of MSTF will provide an opportunity to develop new strategies to combat pathogenic microorganisms, especially Mycobacterium tuberculosis.
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PMID:MSTF: a domain involved in bacterial metallopeptidases and surface proteins, mycobacteriophage tape-measure proteins and fungal proteins. 1663 Feb 59

Reduction of 17-ketosteroids is a biocatalytic process of economic significance for the production of steroid drugs. This reaction can be catalyzed by different microbial 17beta-hydroxysteroid dehydrogenases (17beta-HSD), like the 17beta-HSD activity of Saccharomyces cerevisiae, Pichia faranosa and Mycobacterium sp., and by purified 3beta,17beta-HSD from Pseudomonas testosteroni. In addition to the bacterial 3beta,17beta-HSD the 17beta-HSD of the filamentous fungus Cochliobolus lunatus is the only microbial 17beta-HSD that has been expressed as a recombinant protein and fully characterized. On the basis of its modeled 3D structure, we selected several positions for the replacement of amino acids by site-directed mutagenesis to change substrate specificity, alter coenzyme requirements, and improve overall catalytic activity. Replacement of Val161 and Tyr212 in the substrate-binding region by Gly and Ala, respectively, increased the initial rates for the conversion of androstenedione to testosterone. Replacement of Tyr49 within the coenzyme binding site by Asp changed the coenzyme specificity of the enzyme. This latter mutant can convert the steroids not only in the presence of NADP(+) and NADPH, but also in the presence of NADH and NAD(+). The replacement of His164, located in the non-flexible part of the 'lid' covering the active center resulted in a conformation of the enzyme that possessed a higher catalytic activity.
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PMID:Rational design of novel mutants of fungal 17beta-hydroxysteroid dehydrogenase. 1719 85

The enzymes of the non-mevalonate pathway for isoprenoid biosynthesis are attractive targets for the development of novel drugs against malaria and tuberculosis. This pathway is used exclusively by the corresponding pathogens, but not by humans. A series of water-soluble, cytidine-based inhibitors that were originally designed for the fourth enzyme in the pathway, IspD, were shown to inhibit the subsequent enzyme, the kinase IspE (from Escherichia coli). The binding mode of the inhibitors was verified by co-crystal structure analysis, using Aquifex aeolicus IspE. The crystal structures represent the first reported example of a co-crystal structure of IspE with a synthetic ligand and confirmed that ligand binding affinity originates mainly from the interactions of the nucleobase moiety in the cytidine binding pocket of the enzyme. In contrast, the appended benzimidazole moieties of the ligands adopt various orientations in the active site and establish only poor intermolecular contacts with the protein. Defined binding sites for sulfate ions and glycerol molecules, components in the crystallization buffer, near the well-conserved ATP-binding Gly-rich loop of IspE were observed. The crystal structures of A. aeolicus IspE nicely complement the one from E. coli IspE for use in structure-based design, namely by providing invaluable structural information for the design of inhibitors targeting IspE from Mycobacterium tuberculosis and Plasmodium falciparum. Similar to the enzymes from these pathogens, A. aeolicus IspE directs the OH group of a tyrosine residue into a pocket in the active site. In the E. coli enzyme, on the other hand, this pocket is lined by phenylalanine and has a more pronounced hydrophobic character.
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PMID:Synthesis and characterization of cytidine derivatives that inhibit the kinase IspE of the non-mevalonate pathway for isoprenoid biosynthesis. 1803 14

A large number of human genetic diseases, bacterial drug resistances, and single-nucleotide polymorphisms are caused by gene mutations. Rapid and high-throughput mutation detection methods are urgently demanded. A protein chip method for detection of single-base mismatches and unpaired bases of DNA was developed using a genetic fusion molecular system Trx-His6-(Ser-Gly)6-Strep tagII-(Ser-Gly)6-MutS (THLSLM). The THLSLM coding sequence was constructed by attaching Strep tag II and mutS gene to the vector pET32a (+) sequentially with insertion of a (Ser-Gly)6 coding sequence before and behind Strep tagII gene, respectively. The fusion protein THLSLM was expressed in Escherichia coli AD494 (DE3) and purified using Ni(2+)-chelation affinity resin. The results of bioactivity assay showed that THLSLM both binds to mismatched DNA and interacts with streptavidin. THLSLM was immobilized on the chip matrix coated with the streptavidin through Strep tagII-streptavidin binding reaction. The resulting protein chip was used to detect the mismatched and unpaired mutations in the synthesized oligonucleotides, as well as a single-base mutation in rpoB gene from Mycobacterium tuberculosis, with high specificity. The method could potentially serve as a platform to develop the high-throughput technology for screening and analysis of genetic mutations.
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PMID:Protein chip for detection of DNA mutations. 1822 Feb 31

Due to their high hydrophobicity, it is a challenge to obtain high yields of transmembrane peptides for structural and functional characterization. In the present work, a robust method is developed for the expression, purification and reconstitution of transmembrane peptides, especially for those containing conserved methionines. By using a truncated and mutated glutathione-S-transferase construct as the carrier protein and hydroxylamine (which specifically cleaves the peptide bond between Asn and Gly) as the cleavage reagent, 10 mg of the first transmembrane helix of CorA, a Mg2+ transporter from Mycobacterium tuberculosis, can be conveniently obtained with high purity from 1 L of M9 minimal media under optimized conditions. The biophysical properties of the peptide were studied by circular dichroism and nuclear magnetic resonance spectroscopy, and the results show that this CorA peptide is well folded in detergent micelles and the secondary structure is very similar to that in recent crystal structures. In addition, this CorA construct is oligomeric in perfluoro-octanoic acid micelles. The compatibility with the transmembrane peptides containing conserved methionines, the high yield and the simple process make the present method competitive with other commonly used methods to produce such peptides for structural and functional studies.
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PMID:Chemical cleavage of fusion proteins for high-level production of transmembrane peptides and protein domains containing conserved methionines. 1823 Mar 29

Enzymes of the non-mevalonate pathway for isoprenoid biosynthesis are therapeutic targets for the treatment of important infectious diseases. Whereas this pathway is absent in humans, it is used by plants, many eubacteria and apicomplexan protozoa, including major human pathogens such as Plasmodium falciparum and Mycobacterium tuberculosis. Herein, we report on the design, preparation and biological evaluation of a new series of ligands for IspE protein, a kinase from this pathway. These inhibitors were developed for the inhibition of IspE from Escherichia coli, using structure-based design approaches. Structure-activity relationships (SARs) and a co-crystal structure of Aquifex aeolicus IspE bound to a representative inhibitor validate the proposed binding mode. The crystal structure shows that the ligand binds in the substrate-rather than the adenosine 5'-triphosphate (ATP)-binding pocket. As predicted, a cyclopropyl substituent occupies a small cavity not used by the substrate. The optimal volume occupancy of this cavity is explored in detail. In the co-crystal structure, a diphosphate anion binds to the Gly-rich loop, which normally accepts the triphosphate moiety of ATP. This structure provides useful insights for future structure-based developments of inhibitors for the parasite enzymes.
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PMID:Inhibitors of the kinase IspE: structure-activity relationships and co-crystal structure analysis. 1863 30

Recent polymorphism analyses of Mycobacterium tuberculosis strains have identified missense mutations unique to the W-Beijing lineage in genes belonging to the Nudix hydrolase superfamily. This study investigates the structure and function of one of these Nudix hydrolases, MutT2, and examines the effect that the W-Beijing mutation (G58R) has on enzyme characteristics. MutT2 has a preference for cytidine triphosphates, and although the G58R mutation does not alter nucleotide specificity, it reduces the protein's affinity for divalent cations. The K(D) of free Mg(2+) is 79-fold higher for the G58R mutant (3.30 +/- 0.19 mM) compared with that for the wild-type (41.7 +/- 1.4 microM). Circular dichroism and nuclear magnetic resonance spectroscopy measurements show that while the mutation does not perturb the overall structure of the protein, protein stability is significantly compromised by the presence of the arginine with DeltaG (H(2)O), the free-energy of unfolding, being reduced by 2.48 kcal mol(-1) in the G58R mutant. Homology modeling of MutT2 shows that Gly-58 is in close proximity (10.8 A) to the Mg(2+) binding site formed by the highly conserved Nudix box residues and hydrogen bonds with Ala-54 in the preceding alpha-helix. This may explain the increased divalent cation requirement and decreased stability observed when an arginine is substituted for glycine at this position. A role for MutT2 in the regulation of cytidine-triphosphates available for nucleotide-dependent reactions is postulated, and the impact that the G58R mutation may have on these reactions is discussed.
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PMID:Making sense of a missense mutation: characterization of MutT2, a Nudix hydrolase from Mycobacterium tuberculosis, and the G58R mutant encoded in W-Beijing strains of M. tuberculosis. 1911 62


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