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The EMBO Journal Jul 1995Several examples of inhibition of the function of a ribozyme or RNA-protein complex have shown that certain antibiotics can interact specifically with RNA. There are,...
Several examples of inhibition of the function of a ribozyme or RNA-protein complex have shown that certain antibiotics can interact specifically with RNA. There are, however, few examples of antibiotics that have a positive, rather than a negative, effect on the function of an RNA. We have found that micromolar concentrations of viomycin, a basic, cyclic peptide antibiotic of the tuberactinomycin group, enhance the cleavage of a ribozyme derived from Neurospora VS RNA. Viomycin decreases by an order of magnitude the concentration of magnesium required for cleavage. It also stimulates an otherwise insignificant transcleavage reaction by enhancing interactions between RNA molecules. The ability of viomycin to enhance some RNA-mediated reactions but inhibit others, including translation and Group I intron splicing, demonstrates the potential for natural selection by small molecules during evolution in the 'RNA world' and may have broader implications with respect to ribozyme expression and activity in contemporary cells.
Topics: Enviomycin; Magnesium Chloride; Models, Molecular; Neurospora; Nucleic Acid Conformation; RNA Processing, Post-Transcriptional; RNA, Catalytic; RNA, Fungal; Viomycin
PubMed: 7621836
DOI: 10.1002/j.1460-2075.1995.tb07327.x -
Antimicrobial Agents and Chemotherapy Nov 1992Aqueous solutions of 0.02% isoniazid, 0.2% streptomycin, 0.2% para-aminosalicylate, and 0.5% ethambutol and ethylene glycol solutions of 0.5% ethionamide stored at 3 to...
Aqueous solutions of 0.02% isoniazid, 0.2% streptomycin, 0.2% para-aminosalicylate, and 0.5% ethambutol and ethylene glycol solutions of 0.5% ethionamide stored at 3 to 7 degrees C remained stable for 1 year, as did aqueous solutions of 0.05% ethionamide hydrochloride, 0.05% kanamycin, 0.05% viomycin, and 0.1% capreomycin stored at -20 degrees C. The ethambutol and capreomycin solutions were tested by microbiologic methods; the other solutions were tested by both spectrophotometric and microbiologic methods. Prepared susceptibility testing media made with cycloserine, rifampin, and the above solutions incorporated into Middlebrook 7H10 medium showed acceptable stability when stored at 3 to 7 degrees C for 1 month. During incubation of the test medium at 37 degrees C, approximately half of the activity of isoniazid, ethionamide, ethambutol, cycloserine, and rifampin was lost after periods ranging from 2 to 4 days for ethambutol to 2 weeks for rifampin.
Topics: Antitubercular Agents; Chemistry, Pharmaceutical; Cold Temperature; Drug Stability; Drug Storage; Freezing; Isoniazid; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Solutions; Temperature; Time Factors
PubMed: 1489183
DOI: 10.1128/AAC.36.11.2398 -
FEBS Letters Jan 1992AcPhe2-tRNA(Phe) synthesized in 70S ribosomes after consecutive binding of AcPhe-tRNA(Phe) at the P sites and EF-Tu-directed binding of Phe-tRNA(Phe) at the A sites is...
AcPhe2-tRNA(Phe) synthesized in 70S ribosomes after consecutive binding of AcPhe-tRNA(Phe) at the P sites and EF-Tu-directed binding of Phe-tRNA(Phe) at the A sites is able to react quantitatively with puromycin in the absence of EF-G. A detailed study of the kinetics of the puromycin reaction, its comparison with that of spontaneous translocation, the use of antibiotic viomycin as an effective inhibitor of spontaneous translocation revealed that, besides spontaneous translocation, this peptidyl-tRNA could react with puromycin being located at the A site. This leads to the conclusion that the transpeptidation reaction per se triggers conformational changes in the ribosomal complex bringing the 3'-end of a newly synthesized peptidyl-tRNA nearer to the peptidyl-site of the peptidyltransferase center. This is detected functionally as the ability of such an A site bound peptidyl-tRNA to react with puromycin. This reaction is highly pronounced at elevated (25 degrees C) temperature but can be hardly detected at 0 degrees C.
Topics: Binding Sites; Models, Biological; Protein Biosynthesis; Puromycin; RNA, Transfer, Amino Acyl; RNA, Transfer, Phe; Ribosomes
PubMed: 1733779
DOI: 10.1016/0014-5793(92)80380-y -
Microbiology and Immunology 1992Bacteriostatic and bactericidal activities of rifampicin, isoniazid, streptomycin, enviomycin and ethambutol against Mycobacterium tuberculosis, Mycobacterium avium--M.... (Comparative Study)
Comparative Study
Bacteriostatic and bactericidal activity of antituberculosis drugs against Mycobacterium tuberculosis, Mycobacterium avium-Mycobacterium intracellulare complex and Mycobacterium kansasii in different growth phases.
Bacteriostatic and bactericidal activities of rifampicin, isoniazid, streptomycin, enviomycin and ethambutol against Mycobacterium tuberculosis, Mycobacterium avium--M. intracellulare complex and Mycobacterium kansasii were studied in different growth phases. Bacteriostatic activities of the drugs were similar in different growth phases, except isoniazid. M. tuberculosis was much less susceptible to isoniazid in the lag phase than in the log and the stationary phases. In contrast, bactericidal activity was influenced by the growth phase. M. tuberculosis was killed by isoniazid, streptomycin and rifampicin. The bactericidal activity of isoniazid was strongest. The bactericidal activity of isoniazid and streptomycin was most marked in the log phase. M. avium complex and M. kansasii resisted the bactericidal activity, but some strains of M. avium complex were killed by streptomycin and enviomycin, and the activities of these two drugs were most marked in the lag phase.
Topics: Antitubercular Agents; Cell Division; Enviomycin; Ethambutol; Isoniazid; Microbial Sensitivity Tests; Mycobacterium; Mycobacterium avium Complex; Rifampin; Streptomycin
PubMed: 1406364
DOI: 10.1111/j.1348-0421.1992.tb02035.x -
Journal of Bacteriology Jan 1992Several versatile promoter-probe vectors have been constructed for Streptomyces strains which utilize the production of blue-green light as a measure of transcription...
Several versatile promoter-probe vectors have been constructed for Streptomyces strains which utilize the production of blue-green light as a measure of transcription activity. Three plasmid vectors (two high and one low copy number) and two transposons are described. The multicopy plasmids pRS1106 and pRS1108 contain a transcription terminator and multiple-cloning polylinker upstream of promoterless luciferase (lux) and neomycin resistance reporter genes. Plasmid pHI90 is similar in structure to the pRS vectors except that its single copy number is an advantage for regulation studies or situations in which overexpression is otherwise toxic to the cell. The two transposons carry a promoterless lux cassette cloned such that transposition into a target DNA and fusion to the target's transcription unit occur simultaneously. Tn5351 was created by inserting the luciferase genes near the right end of the viomycin resistance transposon Tn4563. Tn5353 carries the luciferase genes near the right end of a neomycin resistance transposon derived from Tn4556. The size of Tn5353 was minimized by deleting nonessential transposon sequences, making this element small enough to be cloned into phi C31 bacteriophages for efficient transposon delivery to target cells of Streptomyces strains. The two Tnlux transposons have been used to generate Streptomyces coelicolor morphological mutants and to monitor transcription from chromosomal promoters during development.
Topics: Chromosomes, Bacterial; Cloning, Molecular; DNA Probes; DNA Transposable Elements; Genetic Vectors; Luciferases; Mutation; Plasmids; Promoter Regions, Genetic; Recombination, Genetic; Streptomyces; Vibrio
PubMed: 1309525
DOI: 10.1128/jb.174.2.367-376.1992 -
The Journal of Antibiotics Mar 1989The appropriate location and orientation of the kanamycin resistance gene (kmr) cloned on multicopy plasmids were determined by subcloning experiments. The transcription...
The appropriate location and orientation of the kanamycin resistance gene (kmr) cloned on multicopy plasmids were determined by subcloning experiments. The transcription start site was identified by high-resolution S1 mapping and the kmr mRNA was shown to have a long leader of about 400 bp. An additional transcript upstream of the kmr gene was also detected, which ran in the opposite direction and overlapped 2 to 3 nucleotides with the kmr transcript. The presumptive promoter region of this physiologically unidentified RNA was similar to the Escherichia coli promoter consensus sequence both in the -10 and -35 regions, whereas the putative promoter region of the kmr gene exhibited sequence similarities in the -10 region to the promoters of the endoglycosidase H (endoH) and the viomycin phosphotransferase (vph) genes from Streptomyces.
Topics: Base Sequence; Chromosome Mapping; Drug Resistance, Microbial; Kanamycin; Molecular Sequence Data; Promoter Regions, Genetic; Streptomyces; Transcription, Genetic
PubMed: 2708135
DOI: 10.7164/antibiotics.42.413 -
The Journal of Biological Chemistry Sep 1988According to the allosteric three-site model for the ribosomal elongation cycle (Rheinberger, H.J. and Nierhaus, K.H. (1986) J. Biol. Chem. 261, 9133-9139), two types of...
According to the allosteric three-site model for the ribosomal elongation cycle (Rheinberger, H.J. and Nierhaus, K.H. (1986) J. Biol. Chem. 261, 9133-9139), two types of A site (aminoacyl-tRNA site) occupation exist. First is the A site occupation after initiation (i-type), with only one site, the P site (peptidyl-tRNA site), being prefilled with a tRNA (initiator tRNA). Second is the A site occupation after an elongation cycle (e-type), with two prefilled sites, namely the P and E sites containing peptidyl-tRNA and deacylated tRNA, respectively. The individual reactions of the elongation cycle were tested, including both types of A site occupation in the presence of various antibiotics. A test system was used allowing the functional studies to be made with quantitative tRNA binding at 6 mM Mg2+. The following results were obtained: 1) thiostrepton (5 x 10(-6) M) induced a complete block of both EF-(elongation factor) G dependent and EF-G independent translocation, in agreement with older observations. The A-site occupation of the e-type was severely inhibited in contrast to that of the i-type. Thus, thiostrepton blocks the allosteric transitions in both directions, i.e. the transition from pre- to post-translocational state (translocation) and that from the post- to the pre-translocational state (A site occupation of the e-type). In addition the ribosomal binding of EF-G.[3H] GMPPNP was inhibited by about 60%. 2) Similarly, viomycin (5 x 10(-5) M) appears to be an inhibitor of both allosteric transitions, since it strongly inhibited the e-type (but not the i-type) A site occupation in addition to translocation. 3) The aminoglycosides streptomycin, hygromycin B, neomycin, kanamycin, and gentamicin prevented A site occupation of the e-type (residual activity below 15%). Neomycin and hygromycin, in addition, blocked the translocation reaction. Only marginal effects were observed with A site occupation of the i-type. It appears that the inhibition of the A site binding of the e-type (allosteric transition from the post- to the pretranslocational state) is the predominant effect of the misreading-inducing aminoglycosides.
Topics: Aminoglycosides; Anti-Bacterial Agents; Escherichia coli; Galactosyltransferases; Guanylyl Imidodiphosphate; Lincomycin; Magnesium; Models, Genetic; Peptide Elongation Factor G; Peptide Elongation Factors; RNA, Transfer, Amino Acid-Specific; RNA, Transfer, Phe; Ribosomes; Thiostrepton; Viomycin
PubMed: 2843509
DOI: No ID Found -
The Journal of Antibiotics Sep 1988
Topics: Binding Sites; Peptide Chain Elongation, Translational; RNA, Transfer, Phe; Viomycin
PubMed: 2846488
DOI: 10.7164/antibiotics.41.1277 -
The Journal of Antibiotics May 1988Deoxypheganomycin D, a specific inhibitor of mycobacteria, inhibits the growth in vitro of Mycobacterium smegmatis ATCC 607 (M. 607) bacteriostatically at concentrations...
Deoxypheganomycin D, a specific inhibitor of mycobacteria, inhibits the growth in vitro of Mycobacterium smegmatis ATCC 607 (M. 607) bacteriostatically at concentrations as high as 7 X 10(-5) M. It shows no cross-resistance to paromomycin, capreomycin, viomycin, streptothricin, kanamycin and streptomycin. Deoxypheganomycin D at 2.8 X 10(-7) M where the cell growth of M. 607 is only partially inhibited does not significantly inhibit DNA, RNA or protein synthesis but leads to marked decrease (13% of control) in [14C]glycerol-derived radioactivity in cell-walls. In the presence of 7 X 10(-6) M deoxypheganomycin D, the influx of leucine but not thymidine is affected while the reverse is true with efflux. The data suggest that the effect of deoxypheganomycin D on M. 607 may be related to both the cell membrane and specific mycobacterial lipid like components of the cell-wall.
Topics: Amino Acids; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Bacterial Proteins; Cell Membrane Permeability; Cell Wall; DNA, Bacterial; Mycobacterium; Nucleic Acid Precursors; Peptides
PubMed: 3384753
DOI: 10.7164/antibiotics.41.675 -
Journal of Bacteriology Oct 1987A 6.8-kilobase-pair (kbp) transposable element (Tn4556) was found in a neomycin-producing strain of Streptomyces fradiae. This element was first observed in two 30.3-kbp...
A 6.8-kilobase-pair (kbp) transposable element (Tn4556) was found in a neomycin-producing strain of Streptomyces fradiae. This element was first observed in two 30.3-kbp plasmids (pUC1123 and pUC1124) which arose when a thiostrepton resistance gene (1 kbp) was ligated with the BclI-2 fragment (22.5 kbp) that contains the origin of replication of phage SF1. The Tn4556 segment was deleted when these plasmids were transduced into another S. fradiae host with phage SF1. These deletion plasmids (pUC1210 and pUC1211) had copy numbers of less than 1 per chromosome and were unstable. In contrast, pUC1123 and pUC1124, with copy numbers of 12 to 15 per chromosome, respectively, were relatively stable. When pUC1210 and pUC1211 were reintroduced into S. fradiae by protoplast transformation, the Tn4556 element transposed again to the plasmids at numerous new locations in either of two orientations. A copy of Tn4556 was found in the S. fradiae chromosome by hybridization studies. It appears that Tn4556 originated from the chromosome, transposed into unstable pUC1210 and pUC1211, and made stable plasmids. A temperature-sensitive hybrid plasmid carrying a viomycin resistance derivative of Tn4556 (pMT660::Tn4556::vph) was constructed. When Streptomyces lividans UC8390 containing the hybrid plasmid was grown at 39 degrees C, Tn4556::vph (Tn4560) transposed to random positions in the host chromosome.
Topics: Cloning, Molecular; DNA Restriction Enzymes; DNA Transposable Elements; DNA, Bacterial; Drug Resistance, Microbial; Genes, Bacterial; Genetic Vectors; Nucleic Acid Hybridization; Plasmids; Streptomyces; Thiostrepton; Transduction, Genetic; Transformation, Bacterial
PubMed: 2820925
DOI: 10.1128/jb.169.10.4436-4441.1987