aurodox and mocimycin

The elfamycins are a class of naturally occurring antibiotics not currently used in the therapy of human disease. Enterococcus faecium and closely related species (Enterococcus durans and Enterococcus hirae) are susceptible to these antibiotics, while isolates of Enterococcus faecalis and other enterococcal species are highly resistant. Among enterococci, susceptibility or resistance to elfamycins appears to be determined by the bacterial protein synthesis elongation factor EF-Tu. Elfamycin susceptibility may be a useful adjunct for rapidly distinguishing E. faecalis and E. faecium in the clinical microbiology laboratory and/or as a supplementary test for use in determining the species of enterococci.

Topics: Anti-Bacterial Agents; Aurodox; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Enterococcus; Enterococcus faecium; Pyridones

In a previous study (C. C. Hall, J. D. Watkins, and N. H. Georgopapadakou, Antimicrob. Agents Chemother. 33:322-325, 1989), the elongation factor Tu (EF-Tu) from Staphylococcus aureus was found to be insensitive to a series of kirromycin analogs which were inhibitory to the EF-Tu from Escherichia coli. In the present study, the EF-Tu from S. aureus was partially purified and characterized. Its apparent molecular mass was approximately 41,000 Da, and the enzyme copurified with EF-Ts (molecular mass, 34,000 Da). S. aureus EF-Tu differed from its E. coli counterpart in that it bound negligible amounts of [3H]GDP, in addition to being insensitive to pulvomycin and aurodox (50% inhibitory concentrations, approximately 100 and 1,000 microM, respectively, versus 2 and 0.2 microM, respectively, for E. coli). The results are consistent with the formation of a stable EF-Tu.EF-Ts complex that affects the interaction of EF-Tu with guanine nucleotides and inhibitors.

Topics: Adenosine Triphosphatases; Aminoglycosides; Anti-Bacterial Agents; Aurodox; Chromatography, DEAE-Cellulose; Drug Resistance, Microbial; Escherichia coli; Guanosine Diphosphate; Guanosine Triphosphate; Molecular Weight; Peptide Biosynthesis; Peptide Elongation Factor Tu; Peptides; Pyridones; Staphylococcus aureus

Six kirromycin analogs (elfamycins) were compared on the basis of their inhibition of Escherichia coli poly(U)-directed poly(Phe) synthesis and stimulation of elongation factor Tu (EF-Tu)-associated GTPase activity. The elfamycins tested were kirromycin, aurodox, efrotomycin, phenelfamycin A, unphenelfamycin, and L-681,217. The last three lack the pyridone ring present in the other elfamycins. All the elfamycins inhibited poly(U)-dependent poly(Phe) synthesis and stimulated EF-Tu-associated GTPase activity, suggesting that the pyridone ring is not essential for activity. The six elfamycins were also examined in a poly(U)-directed, poly(Phe)-synthesizing system derived from Staphylococcus aureus and had 50% inhibitory concentrations of greater than or equal to 1 mM. When S. aureus ribosomes and E. coli elongation factors were combined in a hybrid poly(Phe)-synthesizing system, aurodox produced essentially complete inhibition of poly(Phe) synthesis with a 50% inhibitory concentration of 0.13 microM. This suggests that the observed high MICs of kirromycin and its congeners in S. aureus reflect a kirromycin-resistant EF-Tu rather than permeability constraints.

Topics: Anti-Bacterial Agents; Aurodox; Escherichia coli; GTP Phosphohydrolase-Linked Elongation Factors; Hybridization, Genetic; Peptide Elongation Factor Tu; Phenylalanine; Phosphorus Radioisotopes; Pyridones; Staphylococcus aureus

The activities of kirromycin oxime, aurodox 2,4-dinitrophenylhydrazone and four O-derivatives of aurodox have been compared to those of kirromycin (mocimycin) and its natural N-methyl analog aurodox in the in vitro system of E. coli. All synthetic derivatives were able to inhibit protein biosynthesis like the original antibiotics. Moreover, the analogs did promote all the effects of kirromycin on the reactions dependent on elongation factor Tu. From these results it can be concluded that the acidic hydroxyl and keto functions of kirromycin and aurodox are not directly involved in the action of the antibiotics on elongation factor Tu and can, thus, be chemically modified without loss of activity. In most cases, however, derivatization lowered the affinity of the antibiotic for elongation factor Tu. This suggests that the pyridone moiety of kirromycin and aurodox and the first part of its side chain should play a role in the association of these antibiotics with elongation factor Tu.

Topics: Anti-Bacterial Agents; Aurodox; Bacterial Proteins; Enzyme Activation; Escherichia coli; GTP Phosphohydrolase-Linked Elongation Factors; Guanosine Diphosphate; Guanosine Triphosphate; Peptide Elongation Factors; Pyridones; RNA, Transfer, Amino Acyl