title: Effects of antibiotics, N-acetylaminoacyl-tRNA and other agents on the elongation-factor-Tu dependent and ribosome-dependent GTP hydrolysis promoted by 2'(3')-O-L-phenylalanyladenosine.
abstract: GTP hydrolysis on elongation factor (EF) Tu . ribosome complexes has been assayed in the presence of 2'(3')-O-L-phenylalanyladenosine (AdoPhe), i.e. the 3'-terminal portion of Phe-tRNAPhe. Several requirements of the reaction have been characterized. Maximal activity is observed at 60-120 mM NH4Cl and 5-15 mM magnesium acetate. The reaction requires the free sulfhydryl group of EF-Tu normally implicated in aminoacyl-tRNA binding. Intact EF-Tu cannot be replaced by a large tryptic fragment of EF-Tu (Mr 39,000) that retains the ability to bind guanosine nucleotides. The aminoglycoside antibiotics, neomycin C and several kanamycins and gentamicins, stimulate the AdoPhe-promoted GTPase. Surprisingly, however, other closely related antibiotics, like neomycin B, paromomycin and ribostamycin, are ineffectual, thus indicating subtle differences in the actions of these antibiotics. AcPhe-tRNAPhe, bound to the ribosomal A-site, stimulates the AdoPhe-promoted GTPase, but this compound or AcTyr-tRNATyr, present in unbound form, strongly inhibits the reaction. These results suggest that N-blocked aminoacyl-tRNAs form ternary complexes with EF-Tu . GTP, which have not been previously detected because of their low stability.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D007700:Kinetics; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects; D010444:Peptide Elongation Factor Tu; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D012346:RNA, Transfer, Amino Acyl / Q000494:pharmacology*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D014357:Trypsin
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D010445:Peptide Elongation Factors; D010446:Peptide Fragments; D012346:RNA, Transfer, Amino Acyl; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D014357:Trypsin; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D010444:Peptide Elongation Factor Tu; D005033:Ethylmaleimide