title: Effect of codon shortening and the antibiotics viomycin and sparsomycin upon the behaviour of bound aminoacyl-tRNA. Decoding at the ribosomal A site.
abstract: 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.
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D055598:Chemical Phenomena; D002621:Chemistry; D003062:Codon / Q000378:metabolism*; D005815:Genetic Code / Q000187:drug effects*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D012333:RNA, Messenger / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D013033:Sparsomycin / Q000494:pharmacology*; D014756:Viomycin / Q000494:pharmacology*
chemical_list: D000903:Antibiotics, Antineoplastic; D003062:Codon; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl; D013033:Sparsomycin; D006160:Guanosine Triphosphate; D014756:Viomycin