Conformational change of elongation factor Tu (EF-Tu) induced by antibiotic binding. Crystal structure of the complex between EF-Tu.GDP and aurodox.
(1/16)
Aurodox is a member of the family of kirromycin antibiotics, which inhibit protein biosynthesis by binding to elongation factor Tu (EF-Tu). We have determined the crystal structure of the 1:1:1 complex of Thermus thermophilus EF-Tu with GDP and aurodox to 2.0-A resolution. During its catalytic cycle, EF-Tu adopts two strikingly different conformations depending on the nucleotide bound: the GDP form and the GTP form. In the present structure, a GTP complex-like conformation of EF-Tu is observed, although GDP is bound to the nucleotide-binding site. This is consistent with previous proposals that aurodox fixes EF-Tu on the ribosome by locking it in its GTP form. Binding of EF-Tu.GDP to aminoacyl-tRNA and mutually exclusive binding of kirromycin and elongation factor Ts to EF-Tu can be explained on the basis of the structure. For many previously observed mutations that provide resistance to kirromycin, it can now be understood how they prevent interaction with the antibiotic. An unexpected feature of the structure is the reorientation of the His-85 side chain toward the nucleotide-binding site. We propose that this residue stabilizes the transition state of GTP hydrolysis, explaining the acceleration of the reaction by kirromycin-type antibiotics. (+info)
Induction of resistance to aurodox by aurodox in the antibiotic-producing culture, Streptomyces goldiniensis.
(2/16)
The sensitivity of protein and aurodox synthesis to aurodox was examined in relationship to the development of resistance to aurodix on Streptomyces goldiniensis during fermentation. It was found that the culture remains sensitive to the antibiotic as long as no aurodox is present in the medium. Resistance only develops when aurodox is present, either exogenously added or endogenously synthesized by the culture. These observations suggest that the development of resistance is an inducible process, and evidence is presented indicating that aurodox induces a specific resistance system in S. goldiniensis. (+info)
A83016F, a new member of the aurodox family.
(3/16)
A new member of the aurodox family of antibiotics, A83016F, has been isolated from an unidentified actionmycete designated A83016. The structure and relative stereochemistry of A83016F were elucidated by NMR examination of the parent compound and its diacetate derivative. A83016F exhibits only weak antimicrobial activity. (+info)
Comparison of the Tu elongation factors from Staphylococcus aureus and Escherichia coli: possible basis for elfamycin insensitivity.
(4/16)
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. (+info)
The structure of heneicomycin.
(5/16)
The antibiotic heneicomycin (1), C44H62N2O11, was isolated from cultures of Streptomyces filipinensis as an amorphous yellow powder. Mass spectral and NMR analysis showed the compound to be a deoxy modification of aurodox (2), a member of the elfamycin antibiotic family. A marked change in mass spectral fragmentation compared to aurodox and 1H NMR couplings indicated the absence of the hydroxyl at position 30 of aurodox (position 3 of the tetrahydropyran). (+info)
Antibiotic SB22484: a novel complex of the aurodox group. I. Taxonomy of the producing organism, isolation of the antibiotics and chemical and biological characterization.
(6/16)
Antibiotic SB22484 is a novel member of the aurodox type antibiotic group produced in submerged-fermentation cultures of Streptomyces sp. NRRL 15496. The antibiotic complex is composed of two pairs of isomers with MW's of 752 and 766. The individual isomers, which were separated by preparative HPLC, equilibrate to a mixture of the isomer pair when left in aqueous solution. In vitro, SB22484 antibiotics strongly inhibited neisseriae and were also active against Streptococci, Ureaplasma urealyticum and Haemophilus influenzae. (+info)
Antibiotic SB22484: a novel complex of the aurodox group. II. Structure elucidation of the four factors.
(7/16)
SB22484, active against Neisseriae gonorrhoeae and Neisseriae meningitidis, is a complex of four factors, designed 1 through 4, which from two pairs of isomers, 1 and 3, and 2 and 4. Factors 1 and 3 account for 65% of the complex, factor 3 being the predominant one. On the basis of the existing and implemented correlations between structure and physico-chemical characteristics (UV and IR spectroscopies, ionization properties, MS as FAB and as negative and positive CI, 1H NMR spectroscopy as 2D COSY and NOESY) in the aurodox field, the complete structures were assigned. Factor 3 can be described as N-[7-[5(R)-[7-[1,2-dihydro-4-hydroxy-1H-2-oxo-3-pyridinyl]-6-methyl- 7-oxo-1(E),3(E),5(E)-heptatrienyl]tetrahydro-3(S),4(R)-dihydrox yfuran-2 (S)-yl]-6(S)-methoxy-5,7(R)-dimethyl-2(E),4(E)-heptadienyl]-alpha (S)-methyl-5(S)-methyltetrahydro-2(S),4(S or R)-dihydroxy-6(S)-[1(E), 3(Z)-pentadienyl]-2H-pyran-2-acetamide. Factor 1 is an epimer of factor 3 with the opposite configuration at the anomeric center. Factors 2 and 4 have an ethyl group instead of the methyl group alpha to the acetamide moiety and are in the same stereochemical relationship as the pair 1 and 3. (+info)
Effects of elfamycins on elongation factor Tu from Escherichia coli and Staphylococcus aureus.
(8/16)
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. (+info)