Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

RNA polymerase (nucleosidetriphosphate: RNA nucleotidyltransferase DNA-dependent), EC 2.7.7.6) was purified approximately 200 fold from Mycobacterium tuberculosis H37RV cells. The purified enzyme has a molecular weight of about 330 000-350 000 and is composed of four subunits. The subunits beta', beta and sigma have molecular weights different from those of Escherichia coli polymerase; the fourth, alpha subunit has a similar weight. The purified enzyme is a thousand-fold more sensitive to rifampicin, a potent antitubercular drug than the E. coli RNA polymerase, probably because of the difference in the beta subunits. This, with other data presented in this paper, indicate that the RNA polymerase of M. tuberculosis differs in its properties from that of E. coli.
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PMID:Purification and properties of DNA-dependent RNA polymerase from Mycobacterium tuberculosis H37RV. 81 87

A strain of Mycobacterium intracellulare that exhibited natural resistance to rifampin was isolated. The ribonucleic acid polymerase was found to be susceptible to rifampin. Studies with Tween 80 suggested that a permeability barrier against rifampin was present in the intact organism. A type strain of Mycobacterium smegmatis, ATCC 607, considered resistant to rifampin also demonstrated a permeability barrier. The possibility that rifampin resistance in naturally occurring strains of mycobacteria and variable levels of resistance in strains of certain species of this organism are due to permeability barriers is discussed.
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PMID:Permeability barrier to rifampin in mycobacteria. 87 32

DNA fragments from Mycobacterium paratuberculosis were cloned in the promoter probe plasmid pKO1. Of 957 recombinant DNA clones, 24 induced synthesis of galactokinase (the reporter gene) when these plasmids were transformed into an Escherichia coli strain deficient for the enzyme. A DNA insert from one putative promoter-containing plasmid, designated pAG5, was sequenced and shown to contain, a characteristic RNA polymerase binding site, a probable ribosomal binding site and a putative open reading frame.
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PMID:Molecular cloning and characterization of Mycobacterium paratuberculosis promoters in Escherichia coli. 145 29

Strains of a new type of slowly growing scotochromogenic mycobacterium were isolated repeatedly from sphagnum vegetation and surface water of moors in New Zealand. These strains grew at 31 and 22 degrees C but not at 37 degrees C and possessed catalase, acid phosphatase, and arylsulfatase activities. They did not split amides, and most of them were susceptible to antituberculotic drugs. Furthermore, they did not tolerate 0.1% NaOH2 and 0.2% picric acid and did not grow on compounds used as single carbon sources and single nitrogen and carbon sources. The internal similarity of the strains as determined by numerical taxonomy methods was 96.6% +/- 3.09%. The whole-mycolate pattern is unique in that it has not been found previously in 23 species of slowly growing mycobacteria. Evaluation of long-reverse-transcriptase-generated stretches of the primary structure of the 16S rRNA confirmed that these organisms belong to the genus Mycobacterium. The phylogenetic position of these bacteria is unique; they are situated between slowly growing pathogenic and rapidly growing saprophytic species. The strains are not pathogenic for mice, guinea pigs, and rabbits, but they provoke a nonspecific hypersensitivity reaction to bovine tuberculin. Hence, they are considered members of a new species of nonpathogenic, slowly growing mycobacteria, for which the name Mycobacterium cookii is proposed. Strain NZ2 is the type strain; a culture of this strain has been deposited in the American Type Culture Collection as strain ATCC 49103.
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PMID:Mycobacterium cookii sp. nov. 169 63

At least two transcriptional initiation sites were observed in rRNA operon of Mycobacterium bovis BCG at approximately -187 and -265. The former transcriptional signal was recognized by Escherichia coli RNA polymerase, whereas the later was not.
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PMID:Analysis of the promoter region in the rRNA operon from Mycobacterium bovis BCG. 172 95

Two long stretches of the 16S from Mycobacterium leprae were sequenced using reverses transcriptase and the chain termination technique. Homology values were calculated for 11 cultivable mycobacteria and a phylogenetic tree constructed from evolutionary distance values (Knuc). Slow and fast growing mycobacteria used in this study form a taxonomic unit but were phylogenetically well separated. It could be confirmed that M. leprae is a true member of the slowly growing pathogenic mycobacteria branching off intermediate to other members of this subgroup. Comparison of the 16 rRNA primary structures reveals that the nucleotide sequence of M. leprae contains regions of sufficient variation to serve as potential target sites for DNA probes. Here we describe the designation of a DNA oligonucleotide and its use in dot blot hybridization experiments were it was directed against bulk RNA isolated from several mycobacteria.
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PMID:The primary structure of the 16SrRNA of Mycobacterium leprae: its use in phylogeny and development of DNA probes. 247 6

The biochemical mechanism of resistance to kanamycin, viomycin, and rifampin in five clinical isolates of Mycobacterium tuberculosis was studied. Resistance to viomycin and kanamycin was attributed to altered ribosomes, whereas resistance to rifampin was attributed to an alteration of RNA polymerase. Ribosomal resistance was, however, not the only way of expressing resistance to viomycin and kanamycin.
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PMID:Alteration of ribosomes and RNA polymerase in drug-resistant clinical isolates of Mycobacterium tuberculosis. 392 38

Deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) isolated from a rifampin-sensitive strain of Mycobacterium smegmatis was 90% inhibited by 1 mug of rifampin per ml; enzyme from a rifampin-resistant mutant was not affected by this concentration of antibiotic. Inhibition of phenylalanine-1-(14)C incorporation by rifampin in growing cultures was complete about 6 min after addition of antibiotic. Under the same conditions, uracil-2-(14)c incorporated was blocked after 1.5 to 2 min. Rifampin kills M. smegmatis very slowly. When rifampin-inhibited cultures were transferred to a rifampin-free medium, there was a partial resumption of uracil-2-(14)C incorporation, even in the presence of chloramphenicol. We conclude that a primary event in the inhibition of M. smegmatis by rifampin is the block of DNA-dependent RNA polymerase.
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PMID:Mechanism of action of rifampin on Mycobacterium smegmatis. 494 61

A new derivative of rifamycin SV, R-75-1, inhibits RNA synthesis in Mycobacterium smegmatis ATCC 607 (M607) at a concentration 10 times lower than rifampicin (RFP). However, both R-75-1 and RFP inhibit RNA polymerase reaction by 50% at the same concentration level (0.05 approximately 0.1 microgram/ml). Both inhibit the initiation process of RNA synthesis. E. coli RNA polymerase of the RFP-resistant strain was resistant to R-75-1. RFP was not inactivated by M607 cell extracts. The inhibitory effect of R-75-1 is markedly diminished if mycobacteria are grown in the medium containing Tween 80. On the basis of these results, the greater activity of R-75-1 to mycobacteria is suggested to be due to the better permeability than RFP.
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PMID:Biochemical study of R-75-1, a new semi-synthetic rifamycin. 616 32

The mechanism of antimicrobial activity of KRM-1648 (KRM), a new rifamycin derivative with potent antimycobacterial activity, was studied. Both KRM and rifampin (RMP) inhibited RNA polymerases from Escherichia coli and Mycobacterium avium at low concentrations: the 50% inhibitory concentrations (IC50s) of KRM and RMP for E. coli RNA polymerase were 0.13 and 0.10 micrograms/ml, respectively, while the IC50s for M. avium RNA polymerase were 0.20 and 0.07 microgram/ml. Both KRM and RMP exerted weak inhibitory activity against Mycobacterium fortuitum RNA polymerase, rabbit thymus RNA polymerases, E. coli DNA polymerase I, and two types of reverse transcriptases. Uptake of 14C-KRM by M. avium reached 18,000 dpm/mg (dry weight) 1.5 h after incubation, while uptake by E. coli cells was slight. KRM was much more effective in inhibiting uptake of 14C-uracil than was RMP (IC50 of KRM, 0.04 microgram/ml; IC50 of RMP, 0.12 microgram/ml). These findings suggest, first, that the potent antimycobacterial activity of KRM is due to inhibition of bacterial RNA polymerase and, second, that the activity of KRM against target organisms depends on target cell wall permeability.
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PMID:Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648. 749 91


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