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)

Hsp70-binding sites were mapped on three antigens, the 16-, 19- and 38-kDa proteins of Mycobacterium tuberculosis, using overlapping synthetic peptides in a competitive-binding assay. In each protein, two or three prominent hsp70-binding sites were identified when peptides 20-amino-acid long were used, predominantly in regions containing clusters of aliphatic amino acids. Although there was an overall concordance in the pattern of peptide binding to hsp70 from bacterial (M. tuberculosis) and mammalian sources (immunoglobulin heavy-chain-binding protein), some differences in the specificity of polypeptide binding and the effect of peptides on ATPase activity were observed.
 ...
PMID:Mapping of Hsp70-binding sites on protein antigens. 820 Mar 54

The recA locus of pathogenic mycobacteria differs from that of nonpathogenic species because it contains large intervening sequences nested in the RecA homology region that are excised by an unusual protein-splicing reaction. In vivo assays indicated that Mycobacterium tuberculosis recA partially complemented Escherichia coli recA mutants for recombination and mutagenesis. Further, splicing of the 85 kDa precursor to 38 kDa MtRecA protein was necessary for the display of its activity, in vivo. To gain insights into the molecular basis for partial and lack of complementation by MtRecA and 85 kDa proteins, respectively, we purified both of them to homogeneity. MtRecA protein, but not the 85 kDa form, bound stoichiometrically to single-stranded DNA in the presence of ATP. MtRecA protein was cross-linked to 8-azidoadenosine 5'-triphosphate with reduced efficiency, and kinetic analysis of ATPase activity suggested that it is due to decreased affinity for ATP. In contrast, the 85 kDa form was unable to bind ATP, in the presence or absence of ssDNA and, consequently, was entirely devoid of ATPase activity. Molecular modeling studies suggested that the decreased affinity of MtRecA protein for ATP and the reduced efficiency of its hydrolysis might be due to the widening of the cleft which alters the hydrogen bonds and the contact area between the enzyme and the substrate and changes in the disposition of the amino acid residues around the magnesium ion and the gamma-phosphate. The formation of joint molecules promoted by MtRecA protein was stimulated by SSB when the former was added first. The probability of an association between the lack and partial levels of biological activity of RecA protein(s) to that of illegitimate recombination in pathogenic mycobacteria is considered.
 ...
PMID:Functional characterization of the precursor and spliced forms of RecA protein of Mycobacterium tuberculosis. 863 60

The gene for transcription termination factor Rho was isolated from Streptomyces lividans ZX7. It encoded a 77-kDa polypeptide (Rho 77) with considerable homology to known Rho factors. An atypical hydrophilic region of 228 residues was found within the N-terminal RNA-binding domain. Only Rho from Micrococcus luteus and Mycobacterium leprae (closely related GC-rich Gram-positive bacteria) had an analogous sequence. Rho 77 was overexpressed in Escherichia coli and purified using an N-terminal hexahistidine-tag. Rho 77 displayed a broad RNA-dependent ATPase activity, with poly(C) RNA being no more than 4-fold more effective than poly(A). This contrasts with the ATPase activity of Rho from E. coli which is stimulated primarily by poly(C) RNA. Rho 77 was a general RNA-dependent NTPase, apparent Km values for NTPs were: GTP 0.13 mM, ATP 0.17 mM, UTP 1.1 mM, and CTP >2 mM. Rho 77 poly(C)-dependent ATPase activity was inhibited by heparin, unlike the E. coli Rho. The antibiotic bicyclomycin inhibited the in vitro RNA-dependent ATPase activity of Rho 77, did not inhibit growth of streptomycetes but delayed the development of aerial mycelia. N-terminal deletion analysis to express a truncated form of Rho (Rho 72, 72 kDa) indicated that the first 42 residues of Rho 77 were not essential for RNA-dependent NTPase activity and were not the targets of inhibition by heparin or bicyclomycin.
 ...
PMID:Isolation and sequencing of the rho gene from Streptomyces lividans ZX7 and characterization of the RNA-dependent NTPase activity of the overexpressed protein. 870 78

DNA and RNA helicases of superfamily I are characterized by seven conserved motifs. The five N-terminal motifs are separated from the two C-terminal ones by a spacer that is highly variable in both sequence and length, suggesting the existence of two distinct domains. Using computer methods for protein sequence analysis, we show that PhoH, an ATP-binding protein that is conserved in Escherichia coli and Mycobacterium leprae, is homologous to the putative N-terminal domain of the helicases, whereas the putative E. coli protein YjhR is homologous to the C-terminal domain. These findings suggest that the N-and C-terminal domains of superfamily I helicases have distinct activities, with only the N-terminal domain having the ATPase activity. It is speculated that PhoH and YjhR have evolved from helicases through deletion of the portions of the helicase genes coding for the C- and N-terminal domain, respectively.
 ...
PMID:Two domains of superfamily I helicases may exist as separate proteins. 877 Dec 13

We characterized the Mycobacterium marinum phagosome by using a variety of endocytic markers to follow the path of the bacteria through a mouse macrophage cell line. Using a laser confocal microscope, we found that the majority of viable M. marinum cells were in nonacidic vacuoles that did not colocalize with the vacuolar proton ATPase (V-ATPase), the calcium-independent mannose-6-phosphate receptor (CI-M6PR), or cathepsin D. In contrast, heat-killed organisms and latex beads were in acidic vacuoles which contained the V-ATPase, the CI-M6PR, and cathepsin D. A population of vesicles that contained live M. marinum labeled with the lysosomal glycoprotein LAMP-1, but the percentage of vacuoles that labeled was lower than for heat-killed organisms or latex beads. When testing live and heat-killed Mycobacterium tuberculosis, we found levels of colocalization with LAMP- and cathepsin D comparable to those for the M. marinum isolate. We conclude that M. marinum, like M. tuberculosis, can circumvent the host endocytic pathway and reside in an intracellular compartment which is not acidic and does not fuse with lysosomes. In addition, we describe a system for sampling a large population of intracellular organisms by using a laser confocal microscope.
 ...
PMID:Differential trafficking of live and dead Mycobacterium marinum organisms in macrophages. 911 92

The complete sequence of the kdp gene region of Clostridium acetobutylicum has been determined. This part of the chromosome comprises two small open reading frames (orfZ and orfY), putatively encoding hydrophobic peptides, and the genes kdpA, kdpB, kdpC, and kdpX, followed by an operon encoding a pair of sensor-effector regulatory proteins (KdpD and KdpE). Except for orfZ, orfY, and kdpX, all genes showed significant homology to the kdp genes of Escherichia coli, encoding a high-affinity potassium transport ATPase and its regulators. The complete genome sequence of Synechocystis sp. strain PCC 6803 and a recently published part of the Mycobacterium tuberculosis genome indicate the existence of a kdp system in these organisms as well, but all three systems comprise neither a second orf upstream of kdpA nor an additional kdpX gene. Expression of the clostridial kdp genes, including the unique kdpX gene, was found to be inducible by low potassium concentrations. A transcription start point could be mapped upstream of orfZ. A promoter upstream of kdpD was active only under noninducing conditions. Lowering the potassium content of the medium led to formation of a common transcript (orfZYkdpABCXDE), with a putative internal RNase E recognition site, which could be responsible for the instability of the common transcript. Except for the two small peptides, all gene products could be detected in in vitro transcription-translation experiments.
 ...
PMID:The kdp system of Clostridium acetobutylicum: cloning, sequencing, and transcriptional regulation in response to potassium concentration. 922 59

Proteins associated with the cell wall peptidoglycan (CW-Pr) of Mycobacterium tuberculosis H37Ra were isolated to evaluate their immunoreactivity and immunoprophylactic properties against experimental tuberculosis. Chemical treatment of the cell wall with trifluoromethanesulfonic acid: anisole (2:1) resulted in the release of three proteins of 71, 60 and 45 kDa as resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A comparative study of immune responses elicited to individual proteins in mice immunized with CW-Pr emulsified in incomplete Freund's adjuvant showed the 71-kDa protein to be the most immunoreactive antigen. This 71-kDa protein was found to cross-react with the 70-kDa heat shock protein from M. leprae and possessed ATPase activity. Mice immunized with the 71-kDa protein exhibited significantly higher immune responses, on the basis of T and B cell reactivity, as compared to a M. bovis Bacillus Calmette Guerin (BCG)-vaccinated group. The culture supernatants collected from 71-kDa stimulated lymphocytes stimulated exhibited increased interferon-gamma and interleukin-2 production. The protective efficacy of the 71-kDa protein in comparison to BCG was determined by challenging the mice with a virulent strain M. tuberculosis H37Rv. The 71-kDa protein was found to be more protective in animals challenged at 8 and 16 weeks post immunization, shown by increased survival rates and decreased viable bacilli counts in the target organs as compared to BCG-vaccinated animals.
 ...
PMID:Immunoprophylactic properties of 71-kDa cell wall-associated protein antigen of Mycobacterium tuberculosis H37Ra. 925 66

The complete nucleotide sequence of the 5936 bp cryptic plasmid pFAJ2600 from Rhodococcus erythropolis NI86/21 was determined. Based on the characteristics of its putative replication genes, repA and repB, pFAJ2600 was assigned to the family of pAL5000-related small replicons identified in Mycobacterium (pAL5000), Corynebacterium (pXZ10142), Brevibacterium (pRBL1), Bifidobacterium (pMB1) and Neisseria (pJD1). The replication systems of these plasmids show striking similarities to the ones used by the ColE2 family of plasmids from Enterobacteria with respect to both trans-acting factors and ori sequences. Two possible plasmid stabilization systems are encoded on pFAJ2600: a site-specific recombinase (PmrA) related to the Escherichia coli Xer proteins for plasmid multimer resolution and an ATPase (ParA) related to the A-type of proteins in sop/par partitioning systems. The proposed replication termination region of pFAJ2600 has features in common with the Ter loci of Bacillus subtilis. Chimeras composed of a pUC18-Cmr derivative inserted in the parA-repA intergenic region of vector pFAJ2600 produced vectors that could be shuttled between Escherichia coli and several Rhodococcus species (R. erythropolis, R. fascians, R. rhodochrous, R. ruber). The pFAJ2600-based shuttle vector pFAJ2574 was stably maintained in R. erythropolis and R. fascians growing under non-selective conditions.
 ...
PMID:Structural analysis of the 6 kb cryptic plasmid pFAJ2600 from Rhodococcus erythropolis NI86/21 and construction of Escherichia coli-Rhodococcus shuttle vectors. 935 18

Vacuolar-type (V) ATPases are thought to be the main determinant of phagosomal acidification. In phagosomes containing mycobacteria, which ostensibly impair the delivery of V-ATPases to the phagosomal membrane, the pH would be expected to be near neutral. This prediction was tested by microfluorescence ratio imaging using macrophages from mice susceptible to mycobacterial infection. Although less acidic than their counterparts containing dead bacteria, phagosomes containing live Mycobacteria bovis were nearly 1 pH unit more acidic than the cytosol, suggesting the existence of alternate H+ transport mechanisms. We therefore investigated whether Na+/H+ exchange (NHE) contributes to phagosomal acidification. Immunoblotting, reverse transcriptase-polymerase chain reaction, and pharmacological studies indicated that NHE1 is the predominant isoform of the exchanger in macrophages. Fractionation revealed that NHE1 is incorporated into the phagosomal membrane, and measurements of pH indicated that it is functional in this location. Nevertheless, acidification of the lumen of phagosomes containing either latex beads or live M. bovis was insensitive to (3-methylsulfonyl-4-piperidinobenzoyl)-guanidine methanesulfonate, a potent inhibitor of NHE1. This may have been due to the absence of an appropriate lumen to cytosol Na+ gradient, because the phagosomal membrane was found to be devoid of Na+/K+ pumps. Unexpectedly, the acidification of M. bovis phagosomes was fully reversed by specific inhibitors of the vacuolar H+-ATPase, suggesting that ATPases are present only transiently or in reduced quantities in the phagosomal membrane. Alternatively, acid equivalents accumulated in endosomes by V-ATPases may be delivered to the mycobacterial phagosome by carrier vesicles devoid of ATPases.
 ...
PMID:Regulation of phagosomal acidification. Differential targeting of Na+/H+ exchangers, Na+/K+-ATPases, and vacuolar-type H+-atpases. 936 53

We have charterized a Mycobacterium smegmatis gene encoding a homolog of the ATP-dependent protease Lon (La). Our identification of a Lon homolog, in conjunction with our previous work, identifies M. smegmatis as the first known example of a eubacterium containing both Lon and a complete 20S proteasome (containing both alpha- and beta-subunits). Despite the significant primary sequence divergence between M. smegmatis Lon (Ms-Lon) and E. coli Lon (Ec-Lon), expression of Ms-Lon was only moderately toxic to E. coli cells. The ability of E. coli cells to tolerate expression of Ms-Lon reveals that Ms-Lon does not recognize and degrade essential E. coli proteins. We conclude that discrimination against nonsubstrate proteins is broadly conserved between Ec-Lon and Ms-Lon. Additional conservation of substrate recognition was demonstrated by the ability of Ms-Lon to degrade efficiently RcsA, a natural substrate of Ec-Lon. Purified Ms-Lon displays chymotrypsin-like specificity in peptidase assays that are stimulated by unfolded protein and supported by nonhydrolyzed nucleotide analogs. Maximal peptidase activity requires ATP or dATP. Replacement of Ms-Lon's catalytic Ser with Ala (S675A), Thr (S675T), or Cys (S675C) reduced to background levels Ms-Lon's in vitro peptidase activity. However, by employing a sensitive in vivo assay, based on the degradation of RcsA, we demonstrated that the S675C variant retained specific protease activity. Finally, variants of Ms-Lon, with substututions at or near S675, reduce the enzyme's basal ATPase activity, suggesting a structural interaction between the peptidase and ATPase active sites of Ms-Lon.
 ...
PMID:The lon protease from Mycobacterium smegmatis: molecular cloning, sequence analysis, functional expression, and enzymatic characterization. 942 59


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