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Dinucleotide codon-anticodon interaction as a minimum requirement for ribosomal as-tRNA binding: stabilisation by viomycin of aa-tRNA in the A site

1980; Oxford University Press; Volume: 8; Issue: 23 Linguagem: Inglês

10.1093/nar/8.23.5813

1362-4962

Reinhard Lührmann,

DNA and Nucleic Acid Chemistry

The requirements for the decoding process at the ribosomal A site have been investigated in the presence of viomycin. For these studies natural mRNA was replaced either by the synthetic oligonucleotide A-U-G(-U)n, with 0≤n≤4, or by a physical mixture of the oligonucleotides A-U-G and various oligo(U) sequences. Thus the effect of the “removal” of selected covalent bonds from the sequence A-U-G(U)n could be studied. When the ribosomal P site contains tRNAfMet, then normally the full hexanucleotide “messenger” A-U-G-U-U-U is needed for the EF-Tu-mediated binding of Phe-tRNA into the A site. However in presence of viomycin the pentanucleotide A-U-G-U-U suffices for this. It is also possible in the presence of viomycin to replace A-U-G-U-U-U with mixtures of A-U-G and U-U-U or A-U-G-U and U-U. In all the above systems the binding of Phe-tRNA required the presence of EF-Tu and GTP. The results suggest that viomycin reinforces interactions between aa-tRNA and the A site after the codon-anticodon recognition step.