Effect of codon shortening and the antibiotics viomycin and sparsomycin upon the behaviour of bound aminoacyl-tRNA Decoding at the ribosomal A site

Abstract70 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·EF-Tu·GTP] and [Pro-tRNA·EF-Tu·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