title: Enacyloxin IIa, an inhibitor of protein biosynthesis that acts on elongation factor Tu and the ribosome.
abstract: This work analyzes the action of enacyloxin Ila, an inhibitor of bacterial protein biosynthesis. Enacyloxin IIa [IC50 on poly(Phe) synthesis approximately 70 nM] is shown to affect the interaction between elongation factor (EF) Tu and GTP or GDP; in particular, the dissociation of EF-Tu-GTP is strongly retarded, causing the Kd of EF- Tu-GTP to decrease from 500 to 0.7 nM. In its presence, the migration velocity of both GTP- and GDP-bound EF-Tu on native PAGE is increased. The stimulation of EF-Tu-GDP dissociation by EF-Ts is inhibited. EF- Tu-GTP can still form a stable complex with aminoacyl-tRNA (aa-tRNA), but it no longer protects aa-tRNA against spontaneous deacylation, showing that the EF-Tu-GTP orientation with respect to the 3' end of aa-tRNA is modified. However, the EF-Tu-dependent binding of aa-tRNA to the ribosomal A-site is impaired only slightly by the antibiotic and the activity of the peptidyl-transferase center, as determined by puromycin reactivity, is not affected. In contrast, the C-terminal incorporation of Phe into poly(Phe)-tRNA bound to the P-site is inhibited, an effect that is observed if Phe-tRNA is bound to the A-site nonenzymatically as well. Thus, enacyloxin IIa can affect both EF-Tu and the ribosomal A-site directly, inducing an anomalous positioning of aa-tRNA, that inhibits the incorporation of the amino acid into the polypeptide chain. Therefore, it is the first antibiotic found to have a dual specificity targeted to EF-Tu and the ribosome.
authors.affiliation: Groupe de Biophysique-Equipe 2, Ecole Polytechnique, France.
authors.forename: R
authors.initials: R
authors.lastname: Cetin
authors.forename: I M
authors.initials: IM
authors.lastname: Krab
authors.forename: P H
authors.initials: PH
authors.lastname: Anborgh
authors.forename: R H
authors.initials: RH
authors.lastname: Cool
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Sugiyama
authors.forename: K
authors.initials: K
authors.lastname: Izaki
authors.forename: A
authors.initials: A
authors.lastname: Parmeggiani
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D015394:Molecular Structure; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects*; D010444:Peptide Elongation Factor Tu / Q000037:antagonists & inhibitors*; D011090:Polyenes / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects*
chemical_list: D001426:Bacterial Proteins; D011090:Polyenes; D011500:Protein Synthesis Inhibitors; D012346:RNA, Transfer, Amino Acyl; C072734:enacyloxin IIa; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D010444:Peptide Elongation Factor Tu