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

Peptide mass fingerprinting is a powerful tool for the identification of proteins. Trypsin is the most widely used enzyme for this purpose. Therefore, 104 protein digests from human Jurkat T cells and Mycobacterium were analyzed considering missed cleavage sites, tryptophan oxidation and N-terminal pyroglutamylation. About 90% of the matched peptides with missed cleavage sites could be classified into three groups: (i) lysine and arginine with a neighbouring proline on the carboxy-terminal side, (ii) neighboring lysines/arginines, and (iii) lysines and arginines with an aspartic acid or glutamic acid residue on either the amino- or carboxy-terminal side. The first group is already accounted for by search programs. The number of missed cleavage sites can be increased without reducing the precision of the database search by taking the other two groups into consideration. Peptides with tryptophan were observed in non, singly (+16 Da) and doubly (+32 Da) oxidized forms. The higher oxidized form was only observed with lower intensity in the presence of the lower oxidized form. Peptides with N-terminal glutamine were found always as pyroglutamate (-17 Da), and in the majority of cases in pairs with unmodified glutamine. These data can be used for the refinement of protein searches by peptide mass fingerprinting.
 ...
PMID:Analysis of missed cleavage sites, tryptophan oxidation and N-terminal pyroglutamylation after in-gel tryptic digestion. 1071 61

The first evidence of the interaction of Mycobacterium tuberculosis with the plasminogen system is herein reported. By FACScan analysis and affinity blotting, lysine-dependent binding of plasminogen to M. tuberculosis was demonstrated. The binding molecules were 30-, 60-, and 66-kDa proteins present in cell wall and soluble protein extracts. The activation of plasminogen, which occurred only in presence of fibrin and was not inhibited by the host serpin, alpha(2)-antiplasmin, was also demonstrated.
 ...
PMID:Binding and activation of human plasminogen by Mycobacterium tuberculosis. 1085 53

A surrogate expression system, based on fusions to the phoA bacterial reporter gene, was used to identify Mycobacterium tuberculosis genes that encode exported proteins and the promoter regions required for their expression in the heterologous host Mycobacterium smegmatis. To assess these results in the context of the complete M. tuberculosis genome sequence, the corresponding genes were identified and computational algorithms were employed to identify signal peptide (SP), transmembrane domain and membrane lipoprotein attachment motifs. This information was used to predict the subset of M. tuberculosis genes that encode exported proteins. Of the 34 genes identified by the phoA method, 22 were classified to encode potential soluble secreted proteins. Among these, 14 genes may encode novel secreted proteins. Six of the remaining 12 genes were predicted to encode membrane lipoproteins and an additional six to encode integral membrane proteins. Published observations of proteins proven to be secreted into M. tuberculosis culture filtrates were reviewed to further characterize the mycobacterial SP motif. It was concluded that mycobacterial SPs are comparable in size to Gram-positive SPs, but certain features are different. In particular, arginine was the predominant N-terminally positively charged amino acid in contrast to lysine in the Gram-positives. The hydrophobic transmembrane segment of the SP was dominated by alanine, in contrast to leucine. At the C-terminal end of the SPs, the (-3, -1) rule (AXA motif) holds, with alanine as the dominant amino acid in both positions, being most dominant in the (-1) position. A high proportion of mature sequences start with aspartic acid in the (+1) position and proline in the (+2) position - the DP motif. The authors propose that the DP sequence serves as a sorting signal, following translocation and cleavage by signal peptidase I. Alternatively, the DP motif may be part of the recognition site for the signal peptidase.
 ...
PMID:Extracytoplasmic proteins of Mycobacterium tuberculosis - mature secreted proteins often start with aspartic acid and proline. 1087 17

Mycobacterium leprae has two high-molecular-mass multimodular penicillin-binding proteins (PBPs) of class A, termed PBP1 and PBP1* [Lepage, Dubois, Ghosh, Joris, Mahapatra, Kundu, Basu, Chakrabarti, Cole, Nguyen-Disteche and Ghuysen (1997) J. Bacteriol. 179, 4627-4630]. PBP1-Xaa-beta-lactamase fusions generated periplasmic beta-lactamase activity when Xaa (the amino acid of PBP1 at the fusion junction) was residue 314, 363, 407, 450 or 480. Truncation of the N-terminal part of the protein up to residue Leu-147 generated a penicillin-binding polypeptide which could still associate with the plasma membrane, whereas [DeltaM1-R314]PBP1 (PBP1 lacking residues Met-1 to Arg-314) failed to associate with the membrane, suggesting that the region between residues Leu-147 and Arg-314 harbours an additional plasma membrane association site for PBP1. Truncation of the C-terminus up to 42 residues downstream of the KTG (Lys-Thr-Gly) motif also generated a polypeptide that retained penicillin-binding activity. [DeltaM1-R314]PBP1 could be extracted from inclusion bodies and refolded under appropriate conditions to give a form capable of binding penicillin with the same efficiency as full-length PBP1. This is, to the best of our knowledge, the first report of a soluble derivative of a penicillin-resistant high-molecular-mass PBP of class A that is capable of binding penicillin. A chimaeric PBP in which the penicillin-binding (PB) module of PBP1 was fused at its N-terminal end with the non-penicillin-binding (n-PB) module of PBP1* retained pencillin-binding activity similar to that of PBP1, corroborating the finding that the n-PB module of PBP1 is dispensable for its penicillin-binding activity.
 ...
PMID:Characterization of derivatives of the high-molecular-mass penicillin-binding protein (PBP) 1 of Mycobacterium leprae. 1092 28

In Corynebacterium glutamicum the LysE carrier protein exhibits the unique function of exporting L-lysine. We here analyze the membrane topology of LysE, a protein of 236 amino acyl residues, using PhoA- and LacZ-fusions. The amino-terminal end of LysE is located in the cytoplasm whereas the carboxy-terminal end is found in the periplasm. Although 6 hydrophobic domains were identified based on hydropathy analyses, only five transmembrane spanning helices appear to be present. The additional hydrophobic segment may dip into the membrane or be surface localized. We show that LysE is a member of a family of proteins found, for example, in Escherichia coil, Bacillus subtilis, Mycobacterium tuberculosis and Helicobacter pylori. This family, which we have designated the LysE family, is distantly related to two additional protein families which we have designated the YahN and CadD families. These three families, the members of which exhibit similar sizes, hydropathy profiles, and sequence motifs comprise the LysE superfamily. Functionally characterized members of the LysE superfamily export L-lysine, cadmium and possibly quarternary amines. We suggest that LysE superfamily members will prove to catalyze export of a variety of biologically important solutes.
 ...
PMID:The LysE superfamily: topology of the lysine exporter LysE of Corynebacterium glutamicum, a paradyme for a novel superfamily of transmembrane solute translocators. 1094 64

Granulysin, a protein located in the acidic granules of human NK cells and cytotoxic T cells, has antimicrobial activity against a broad spectrum of microbial pathogens. A predicted model generated from the nuclear magnetic resonance structure of a related protein, NK lysin, suggested that granulysin contains a four alpha helical bundle motif, with the alpha helices enriched for positively charged amino acids, including arginine and lysine residues. Denaturation of the polypeptide reduced the alpha helical content from 49 to 18% resulted in complete inhibition of antimicrobial activity. Chemical modification of the arginine, but not the lysine, residues also blocked the antimicrobial activity and interfered with the ability of granulysin to adhere to Escherichia coli and Mycobacterium tuberculosis. Granulysin increased the permeability of bacterial membranes, as judged by its ability to allow access of cytosolic ss-galactosidase to its impermeant substrate. By electron microscopy, granulysin triggered fluid accumulation in the periplasm of M. tuberculosis, consistent with osmotic perturbation. These data suggest that the ability of granulysin to kill microbial pathogens is dependent on direct interaction with the microbial cell wall and/or membrane, leading to increased permeability and lysis.
 ...
PMID:Granulysin, a T cell product, kills bacteria by altering membrane permeability. 1112 Aug 40

In an attempt to investigate the molecular basis of pyrazinamide hydrolysis by the PncA protein from Mycobacterium tuberculosis, we determined the pyrazinamidase activity of nine PncA mutants bearing a single amino acid substitution. Among them, three mutants (D8G, K96T and S104R) had virtually no activity (< or =0.004 unit/mg), five (F13S, T61P, P69L, Y103S and A146V) retained a low level of activity (0.06-0.25 unit/mg) and one (T167L) exhibited a wild-type activity (1.51 units/mg). The possible structural effects of these substitutions were assessed by analysing a three-dimensional model of the PncA protein constructed on the basis of the crystal structure of the N-carbamoylsarcosine amidohydrolase (CSHase) from Arthrobacter sp., an amidohydrolase which was found by hydrophobic cluster analysis to be closely related to PncA. In the PncA model, five of the mutated residues, Asp-8, Phe-13, Lys-96, Tyr-103 and Ser-104, were located within a 6 A sphere around the cysteine residue Cys-138, which could be the counterpart of the active cysteine residue Cys-177 found in the CSHase. Among the remaining mutated residues, Thr-61, Pro-69 and Ala-146 were found to be more distant from Cys-138 but were associated with structural elements contributing to the catalytic centre, whereas Thr-167 was situated in an alpha-helix located far from the putative active site. These data suggest that the decrease in pyrazinamidase activity observed in the PncA mutant proteins is well correlated with the structural modifications the mutations can cause in the environment of the putative active cysteine Cys-138.
 ...
PMID:Study of the structure-activity relationships for the pyrazinamidase (PncA) from Mycobacterium tuberculosis. 1117 Oct 40

Shepard's technique for growth of Mycobacterium leprae in the mouse footpad, described in 1960, and more recent studies in thymectomized-irradiated mice and rats, athymic nude mice, nude rats and severe combined immunodeficiency (SCID) mice have defined the role of T-cell mediated immunity (CMI) in leprosy. However, the normal mouse and the immunocompromised mouse and rat represent only elements of polar tuberculoid disease and polar lepromatous leprosy, respectively. Transgenic, knockout (KO) mice may be employed to study the roles of individual genes in the ability of the host to mount an effective immune response to pathogens, and may also allow development of mouse models for the immunologically unstable borderline areas of the spectrum. We are exploiting certain KO mice to improve our understanding of CMI to M. leprae, and to study the role of the microenvironment of the leprosy granuloma in pathogenesis. CGD (chronic granulomatous disease) mice and iNOS-KO mice lack the ability to produce reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), respectively, whereas the T cells of GKO mice are unable to produce interferon-gamma (IFN gamma). iNOS-KO mice exhibit an enhanced capacity to form granulomas, and the histopathology of the infected footpad tissues of this strain share many elements of borderline tuberculoid disease. The macrophages of CGD mouse kill or inhibit multiplication of M. leprae, although they lack ROI. Multiplication of the organisms in the footpad is enhanced in GKO mice, although these mice retain some host resistance. In addition, we have been investigating supplementary, conditional approaches to KO mouse models. For example, the down-regulatory effects of local prostaglandin production can be controlled with essential fatty acid deficient diets or indomethacin, RNI can be blocked in CGD and GKO mice by treatment with aminoguanidine, NG monomethyl arginine or N6-(1-iminoethyl)-L-lysine, and local elaboration of TNF alpha can be neutralized by anti-TNF alpha antibody or excess TNF alpha receptor. Other cytokines can be neutralized by antibody as well, broadening the range of conditional knockout models.
 ...
PMID:Exploitation of gene knockout mice models to study the pathogenesis of leprosy. 1120 77

It has been demonstrated that the alpha2 chain of laminin-2 present on the surface of Schwann cells is involved in the process of attachment of Mycobacterium leprae to these cells. Searching for M. leprae laminin-binding molecules, in a previous study we isolated and characterized the cationic proteins histone-like protein (Hlp) and ribosomal proteins S4 and S5 as potential adhesins involved in M. leprae-Schwann cell interaction. Hlp was shown to bind alpha2-laminins and to greatly enhance the attachment of mycobacteria to ST88-14 Schwann cells. In the present study, we investigated the laminin-binding capacity of the ribosomal proteins S4 and S5. The genes coding for these proteins were PCR amplified and their recombinant products were shown to bind alpha2-laminins in overlay assays. However, when tested in ELISA-based assays and in adhesion assays with ST88-14 cells, in contrast to Hlp, S4 and S5 failed to bind laminin and act as adhesins. The laminin-binding property and adhesin capacity of two basic host-derived proteins were also tested, and only histones, but not cytochrome c, were able to increase bacterial attachment to ST88-14 cells. Our data suggest that the alanine/lysine-rich sequences shared by Hlp and eukaryotic H1 histones might be involved in the binding of these cationic proteins to laminin.
 ...
PMID:Further biochemical characterization of Mycobacterium leprae laminin-binding proteins. 1128 56

Defensins, antimicrobial peptides of the innate immune system, protect human mucosal epithelia and skin against microbial infections and are produced in large amounts by neutrophils. The bacterial pathogen Staphylococcus aureus is insensitive to defensins by virtue of an unknown resistance mechanism. We describe a novel staphylococcal gene, mprF, which determines resistance to several host defense peptides such as defensins and protegrins. An mprF mutant strain was killed considerably faster by human neutrophils and exhibited attenuated virulence in mice, indicating a key role for defensin resistance in the pathogenicity of S. aureus. Analysis of membrane lipids demonstrated that the mprF mutant no longer modifies phosphatidylglycerol with l-lysine. As this unusual modification leads to a reduced negative charge of the membrane surface, MprF-mediated peptide resistance is most likely based on repulsion of the cationic peptides. Accordingly, inactivation of mprF led to increased binding of antimicrobial peptides by the bacteria. MprF has no similarity with genes of known function, but related genes were identified in the genomes of several pathogens including Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Enterococcus faecalis. MprF thus constitutes a novel virulence factor, which may be of general relevance for bacterial pathogens and represents a new target for attacking multidrug resistant bacteria.
 ...
PMID:Staphylococcus aureus resistance to human defensins and evasion of neutrophil killing via the novel virulence factor MprF is based on modification of membrane lipids with l-lysine. 1134 91


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>