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At least 55 records · Page 3Linked to original sources
PubMed2003

Deciphering tuberactinomycin biosynthesis: isolation, sequencing, and annotation of the viomycin biosynthetic gene cluster.

The tuberactinomycin antibiotics are essential components in the drug arsenal against Mycobacterium tuberculosis infections and are specifically used for the treatment of multidrug-resistant tuberculosis. These antibiotics are also being investigated for their targeting of the catalytic RNAs involved in viral replication and for the treatment of bacterial infections caused by methicillin-resistant Staphylococcus aureus strains and vancomycin-resistant enterococci. We report on the isolation, sequencing, and annotation of the biosynthetic gene cluster for one member of this antibiotic family, viomycin, from Streptomyces sp. strain ATCC 11861. This is the first gene cluster for a member of the tuberactinomycin family of antibiotics sequenced, and the information gained can be extrapolated to all members of this family. The gene cluster covers 36.3 kb of DNA and encodes 20 open reading frames that we propose are involved in the biosynthesis, regulation, export, and activation of viomycin, in addition to self-resistance to the antibiotic. These results enable us to predict the metabolic logic of tuberactinomycin production and begin steps toward the combinatorial biosynthesis of these antibiotics to complement existing chemical modification techniques to produce novel tuberactinomycin derivatives.

Amino Acids↗
PubMed1987

Characterization of suppressible mutations in the viomycin phosphotransferase gene of the Streptomyces enteric plasmid pVE138.

The viomycin phosphotransferase gene (vph) is expressed and confers resistance to viomycin in both Streptomyces spp. and members of the family Enterobacteriaceae. We report the isolation of UGA (opal) and UAG (amber) mutations in the vph gene of shuttle plasmid pVE138. We found that the five UGA mutations in vph resulted in a temperature-sensitive phenotype in Salmonella typhimurium. Su- strains are Vior at 28 degrees C and Vios at 37 degrees C, whereas Su+UGA strains are Vior at both 28 and 37 degrees C. The single amber mutation isolated was not temperature sensitive and resulted in the expected Vios phenotype in Su- strains and Vior in Su+UAG strains.

DNA Restriction Enzymes↗
PubMed1983

Effect of codon shortening and the antibiotics viomycin and sparsomycin upon the behaviour of bound aminoacyl-tRNA. Decoding at the ribosomal A site.

70 S ribosomes were programmed with initiator tRNA and messenger oligonucleotides AUG(U)n and AUG(C)n, where n = 1, 2 or 3. The binding of the ternary complexes [Phe-tRNA X EF-Tu X GTP] and [Pro-tRNA X EF-Tu X GTP] to the programmed ribosomes was studied. If codon-anticodon interaction is restricted to only one basepair, the ternary complex leaves the ribosome before GTP hydrolysis. Two basepairs allow hydrolysis of GTP, but the aminoacyl-tRNA dissociates and is recycled, resulting in wastage of GTP. Three basepairs result in apparently stable binding of aminoacyl-tRNA to the ribosome. The antibiotic sparsomycin weakens the binding by an amount roughly equivalent to one messenger base, while viomycin has the reverse effect.

Antibiotics, Antineoplastic↗
PubMed1978

Qualitative aspects of hydrogen-deuterium exchange in the 1H, 13C, and 15N nuclear magnetic resonance spectra of viomycin in aqueous solution.

The 1H, 13C, and 15N high field nuclear magnetic resonance spectra of the cyclic peptide viomycin have been fully assigned using homo- and heteronuclear double resonance experiments and pH effects. In addition it is shown how the two- and three-bond H-D isotope effects upon carbonyl resonances may assist in their assignment. The resistance to exchange with solvent water of the amide proton involved in the transannular hydrogen bond is observed directly in the 1H spectra, via the isotope effect on a carbonyl resonance in the 13C spectra, and via the one-bond 1H couppling in the 15N spectra.

Carbon Isotopes↗
PubMed1982

The ototoxic interaction of viomycin, capreomycin and polymyxin B with ethacrynic acid.

The ototoxic interaction between the aminoglycoside antibiotics (streptomycin, kanamycin, etc.) and the loop-inhibiting diuretics (ethacrynic acid, furosemide and bumetanide) has been well documented. This interaction causes extensive destruction of the hair cells of the cochlea. Brummett et al. (1974) demonstrated that this interaction did not occur with the non-loop-inhibiting diuretics and kanamycin. The present study was undertaken to determine if antibiotics other than the aminoglycosides could produce the ototoxic interaction when combined with a loop-inhibiting diuretic. Three antibiotics-viomycin, capreomycin, and polymyxin B- when given with ethacrynic acid were found to produce cochlear hair cell damage that was similar to that produced by aminoglycoside antibiotics administered with ethacrynic acid. Therefore, the interaction appears to be specific to the loop-inhibiting diuretics but not specific for the aminoglycoside antibiotics.

Aminoglycosides↗
PubMed1988

The allosteric three-site model for the ribosomal elongation cycle. New insights into the inhibition mechanisms of aminoglycosides, thiostrepton, and viomycin.

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.

Aminoglycosides↗