Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Uranyl ions (UO2+(2)) and lanthanide cations (La3+, Nd3+, Sm3+, Eu3+, Tb3+ and Dy3+) at 100-200 microM concentration inhibited active transport of Ca2+, mediated by respiratory linked substrates as well as by ATP hydrolysis, without affecting respiration and membrane-bound ATPase activity, in inside-out membrane vesicles of Mycobacterium phlei. The extent of inhibition in the uptake of Ca2+, mediated by ATP hydrolysis, increased with increase in ionic radii of these cations. Lanthanide cations did not dissipate the formation of a proton gradient, as measured by determining the effect either on the uptake of [14C]methylamine or energy-linked quenching of the fluorescence of 9-aminoacridine. However, uranyl ion (UO2+(2+)) caused reversal of the energy-linked quenching of 9-aminoacridine. UO2+(2)) concentration yielding 50% of Vmax (S0.5) was approx. 15 microM. Kinetic studies revealed that inhibition in the uptake of Ca2+ was competitive with UO2+(2) while non-competitive with rare-earth metals. It is proposed that inhibition in the uptake of Ca2+ by uranyl ion occurs as a result of UO2+(2) transport into the interior of vesicles in exchange for protons, while lanthanide cations are not being transported but affect the binding of Ca2+ to the membrane, presumably to the Ca2+/H+ antiporter.
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PMID:Interaction of lanthanide cations and uranyl ion with the calcium/proton antiport system in Mycobacterium phlei. 683 72

In the framework of the mycobacterial genome sequencing project, a continuous 37,049 bp sequence from the Mycobacterium leprae chromosome has been determined. Computer analysis revealed 10 complete open reading frames, and nine of their products show similarity to known proteins. Seven of these were identified as the enzyme isocitrate lyase, two P-type ATPase cation transporters, two AMP-binding proteins, the ribosomal protein S1, and DNA polymerase I. Interestingly, the polA gene, encoding DNA polymerase, is flanked by two inverted copies of a new class of the M. leprae specific repetitive sequence, RLEP, and this structure resembles a transposable element. A second copy of this element was found at another locus in the genome, but the two copies were not present in equal amounts and could not be found in all isolates of M. leprae. This is the first evidence for genomic variability in the leprosy bacillus and might ultimately be useful for developing a molecular test capable of distinguishing between strains of M. leprae.
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PMID:The Mycobacterium leprae genome: systematic sequence analysis identifies key catabolic enzymes, ATP-dependent transport systems and a novel polA locus associated with genomic variability. 747 88

The nucleotide sequence of the amidase operon of Pseudomonas aeruginosa has been completed and two new genes identified amiB and amiS. The complete gene order for the operon is thus amiEBCRS. The amiB gene encodes a 42-kDa protein containing an ATP binding motif that shares extensive homology with the Clp family of proteins and also to an open reading frame adjacent to the amidase gene from Rhodococcus erythropolis. Deletion of the amiB gene has no apparent effect on inducible amidase expression and it is thus unlikely to encode a regulatory protein. A maltose-binding protein-AmiB fusion has been purified and shown to have an intrinsic ATPase activity (Km = 174 +/- 15 mM; Vmax = 2.4 +/- 0.1 mM/min/mg), which is effectively inhibited by ammonium vanadate and ADP. The amiS gene encodes an 18-kDa protein with a high content of hydrophobic residues. Hydropathy analysis suggests the presence of six transmembrane helices in this protein. The AmiS sequences is homologous to an open reading frame identified adjacent to the amidase gene from Mycobacterium smegmatis and to the ureI gene from the urease operon of Helicobacter pylori. AmiS and its homologs appear to be a novel family of integral membrane proteins. Together AmiB and AmiS resemble two components of an ABC transporter system.
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PMID:Identification of two new genes in the Pseudomonas aeruginosa amidase operon, encoding an ATPase (AmiB) and a putative integral membrane protein (AmiS). 764 33

Despite the potential role of the macrophage in the eradication of invading microbes, Mycobacterium species have evolved mechanisms to ensure their survival and replication inside the macrophage. Particles phagocytosed by macrophages normally will be delivered into acid lysosomal compartments for degradation. Mycobacterium must, in some way, avoid this fate by modulation of their phagosome. Immunoelectron microscopy of macrophages infected with Mycobacterium avium or Mycobacterium tuberculosis indicates that the vacuolar membrane surrounding the bacilli possesses the late endosomal/lysosomal marker, LAMP-1 (lysosomal-associated membrane protein-1), but lacks the vesicular proton-ATPase. Analysis of the intersection of the bacteria-containing vacuoles with the endocytic network of the macrophage supports previous studies indicating that these bacilli restrict the fusion capability of their intracellular compartments. The occurrence of vesicles containing lipoarabinomannan, discrete from those containing Mycobacterium, indicate that material does traffic out from the mycobacterial vacuole. To compensate for this loss of membrane, the vacuole must remain dynamic and fuse with LAMP-1-containing vesicles to maintain the density of this marker.
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PMID:Intracellular trafficking in Mycobacterium tuberculosis and Mycobacterium avium-infected macrophages. 807 67

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.
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PMID:Mapping of Hsp70-binding sites on protein antigens. 820 Mar 54

The success of Mycobacterium species as pathogens depends on their ability to maintain an infection inside the phagocytic vacuole of the macrophage. Although the bacteria are reported to modulate maturation of their intracellular vacuoles, the nature of such modifications is unknown. In this study, vacuoles formed around Mycobacterium avium failed to acidify below pH 6.3 to 6.5. Immunoelectron microscopy of infected macrophages and immunoblotting of isolated phagosomes showed that Mycobacterium vacuoles acquire the lysosomal membrane protein LAMP-1, but not the vesicular proton-adenosine triphosphatase (ATPase) responsible for phagosomal acidification. This suggests either a selective inhibition of fusion with proton-ATPase-containing vesicles or a rapid removal of the complex from Mycobacterium phagosomes.
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PMID:Lack of acidification in Mycobacterium phagosomes produced by exclusion of the vesicular proton-ATPase. 830 69

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.
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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.
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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.
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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.
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PMID:Differential trafficking of live and dead Mycobacterium marinum organisms in macrophages. 911 92


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