RESUMO
Individual ribosomal proteins S4, S9 and S13 were tested for their ability to interact with tRNA and synthetic polynucleotides. All three proteins bind to immobilized to Sepharose poly(A) and poly(U), while S4 and S13 form stoichiometric (1:1) complexes with tRNA in solution. We show that only the polynucleotide X S13 complexes are able to select their cognate tRNAs. In particular, the affinity of tRNAPhe to the binary poly(U) X S13 complex is about three orders of magnitude higher than that for poly(U) alone.
Assuntos
Escherichia coli/genética , RNA de Transferência/genética , Proteínas Ribossômicas/genética , Ribossomos/metabolismo , Cinética , Poli A/metabolismo , Poli U/metabolismo , Ligação Proteica , Aminoacil-RNA de Transferência/genética , Proteínas Ribossômicas/metabolismoRESUMO
Polyadenylic acid, polycytidylic acid, polyuridylic acid or phage MS2 RNA, immobilized on Sepharose, form a complex with Escherichia coli ribosomal proteins. Regardless of their particular nucleotide composition, all four polynucleotides bind an invariable set of proteins consisting of S1, S3, S4, S5, S9, S13, L2 and L17. We found that these polynucleotide . protein complexes bind tRNA. Furthermore, it was possible to show that the poly(A) . protein and poly(U) . protein complexes select efficiently their cognate tRNAs, tRNALys and tRNAPhe respectively. This important functional property of the polynucleotide . protein complexes suggests that these ribosomal proteins belong in the ribosome to a functional domain responsible for the decoding of mRNA.
