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Query: UMLS:C0026918 (Mycobacterium)
 52,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is not known how Mycobacterium leprae obtains energy for survival and growth in the host tissues; the organism does not grow in vitro. In the studies reported here, M. leprae incorporated labelled ATP, which was blocked by cyanide, unlabelled ATP or ADP, but not by adenosine or Pi. It seems that the organism takes up unhydrolysed ATP by an active transport process. The bacterium contained a membrane-bound, vanadate-sensitive E1 E2-ATPase (which creates a transmembrane potential driving transport of solutes into cells). The enzyme was not inhibited by N-ethylmaleimide, suggesting that it is not an F0F1-ATPase which catalyses ATP synthesis. Apparently, M. leprae derives energy-rich compounds from the host cell.
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PMID:Active transport of ATP and presence of a vanadate-sensitive membrane-bound ATPase in Mycobacterium leprae. 183 12

A number of mycobacterial proteins have been shown to induce strong humoral and cellular immune responses, including the 70-kDa antigen (p70) of Mycobacterium leprae and Mycobacterium bovis. On the basis of sequence homology and an ATP binding ability, p70 has previously been tentatively allocated to the 70-kDa family of heat shock proteins (hsp70). We have purified the M. bovis p70 antigen and described ATPase and Ca(2+)-dependent autophosphorylating activities. These co-purified with p70 on gel chromatography and were up-regulated by native proteins and down-regulated by peptides. Inhibitory peptides were shown to bind p70. These data imply close functional similarities of mycobacterial p70 to other members of the hsp70 family, the Escherichia coli homologue dnaK in particular.
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PMID:Characterization of the functional properties of the 70-kDa protein of Mycobacterium bovis. 183 49

Electron transport particles prepared from Mycobacterium phlei were depleted of bound coupling factors by washing with water in the absence of inorganic ions. The depleted electron transport particles were void of latent ATPase activity and were capable of oxidation, but were unable to support coupled phosphorylation. Nevertheless, the depleted electron transport particles were capable of substrate-induced active transport of proline. Changes in pH in response to substrate oxidation were measured in normal and depleted electron particles with bromthymol blue. A bromthymol blue response upon substrate oxidation was not observed with depleted electron transport particles. The level of oxidative phosphorylation with succinate or NADH oxidation was not reduced in the presence of proline, and proline did not have an effect upon the proton gradients formed by the oxidation of either succinate or NADH.
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PMID:Relationship of a proton gradient to the active transport of proline with membrane vesicles from Mycobacterium phlei. 436 28

Interaction of N,N'-dicyclohexylcarbodiimide (DCCD) with ATPase of Mycobacterium phlei membranes results in inactivation of ATPase activity. The rate of inactivation of ATPase was pseudo-first order for the initial 30-65% inactivation over a concentration range of 5-50 microM DCCD. The second-order rate constant of the DCCD-ATPase interaction was k = 8.5 X 10(5) M-1 X min(-1). The correlation between the initial binding of [14C]DCCD and 100% inactivation of ATPase activity shows 1.57 nmol DCCD bound per mg membrane protein. The proteolipid subunit of the F0F1-ATPase complex in membranes of M. phlei with which DCCD covalently reacts to inhibit ATPase was isolated by labeling with [14C]DCCD. The proteolipid was purified from the membrane in free and DCCD-modified form by extraction with chloroform/methanol and subsequent chromatography on Sephadex LH-20. The polypeptide was homogeneous on SDS-acrylamide gel electrophoresis and has an apparent molecular weight of 8000. The purified proteolipid contains phosphatidylinositol (67%), phosphatidylethanolamine (18%) and cardiolipin (8%). Amino acid analysis indicates that glycine, alanine and leucine were present in elevated amounts, resulting in a polarity of 27%. Cysteine and tryptophan were lacking. Butanol-extracted proteolipid mediated the translocation of protons across the bilayer, in K+-loaded reconstituted liposomes, in response to a membrane potential difference induced by valinomycin. The proton translocation was inhibited by DCCD, as measured by the quenching of fluorescence of 9-aminoacridine. Studies show that vanadate inhibits the proton gradient driven by ATP hydrolysis in membrane vesicles of M. phlei by interacting with the proteolipid subunit sector of the F0F1-ATPase complex.
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PMID:Purification and functional properties of the DCCD-reactive proteolipid subunit of the H+-translocating ATPase from Mycobacterium phlei. 622 56

We have measured the inhibitory potencies of local anesthetics (procaine, lidocaine, tetracaine and dibucaine) on ATP-mediated H+-translocation, Ca2+-transport and ATPase activity in membrane vesicles from Mycobacterium phlei. Procaine and lidocaine up to 1 mM concentration did not inhibit ATP-dependent H+-translocation, Ca2+-transport and ATPase activity. However, tetracaine and dibucaine at 0.2 mM concentration caused dissipation of the proton gradient, measured by the reversal of the quenching of fluorescence of quinacrine, and inhibition of active Ca2+-transport. Tetracaine (1 mM) inhibited membrane-bound ATPase activity without affecting solubilized F1-ATPase activity. Studies show that these local anesthetics do not prevent the inactivation of F0-F1 ATPase by dicyclohexylcarbodiimide (DCCD). Binding of [14C]DCCD to F0-proteolipid component remained unchanged in the presence of tetracaine indicating that DCCD and tetracaine do not share common binding sites on the F0-proteolipid sector. The inhibition of H+-translocation and membrane-bound ATPase activity by tetracaine was substantially additive in the presence of vanadate.
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PMID:Studies on the mechanism of action of local anesthetics on proton translocating ATPase from Mycobacterium phlei. 623 Oct 50

The optimal pH range was from 7.0 to 7.5 in oxidative phosphorylation coupled to nitrate reduction. A cell-free extract of Escherichia coli showed weak myokinase activity. Oxidative phosphorylation coupled to nitrate reduction occurred with fractions of cell-free extracts of Mycobacterium avium. Soluble and particulate fractions separated from the cell-free extract of the organism were necessary for oxidative phosphorylation coupled to nitrate reduction. Each soluble fraction could be replaced by that obtained from another organism, e.g. Escherichia coli, Pseudomonas aeruginosa, and Mycobacterium avium. This suggests the existence of coupling factors common to these soluble fractions, and the possibility that the coupling factors are ATPase and components of the ATP-Pi exchange reaction. The P/NO3- ratio depended more on soluble fractions than on particulate fractions. Both phosphorylation and nitrate reduction activity were reduced by washing particulate fractions of Escherichia coli with 0.1 M KCl, while the P/NO3- ratio slightly increased.
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PMID:Oxidative phosphorylation coupled with nitrate respiration. IV. Replacement of soluble fraction from Escherichia coli, Pseudomonas aeruginosa and Mycobacterium avium. 677 36

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


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