Biosynthesis of reovirus-specified polypeptides: effect of point mutation of the sequences flanking the 5'-proximal AUG initiator codons of the reovirus S1 and S4 genes on the efficiency of mRNA translation.
The effect on translation of site-directed nucleotide substitutions around the 5'-proximal AUG initiation codon of the reovirus s1 mRNA specifying polypeptide sigma 1 and the reovirus s4 mRNA specifying polypeptide sigma 3 was examined. The efficiency of synthesis of the S1-encoded sigma 1 polypeptide and the S4-encoded sigma 3 polypeptide was analyzed in transfected simian COS cells. Mutant s1 mRNAs possessing either GCU AUG G or GCA AUG G sequences surrounding the 5'-proximal sigma 1 AUG were translated with an efficiency comparable to that of the wild-type s1 mRNA which possesses the flanking sequence CCU AUG G. Mutant s4 mRNAs possessing either CCU AUG G or CCA AUG G sequences surrounding the 5'-proximal sigma 3 AUG were translated with an efficiency comparable to that of wild-type s4 mRNA which possesses the flanking sequence GCA AUG G. The s4 mRNAs, both wild-type and mutant, were translated in vivo about five times more efficiently than the s1 mRNAs, both wild-type and mutant. These results suggest that nucleotide positions other than the -3, -2, -1, and +4 positions relative to the 5'-proximal initiator AUG, where the A is +1, play a dominant role in determining the efficiency of translation of these two reovirus mRNAs in vivo.
Munemitsu
S M
SM
Department of Biological Sciences, University of California, Santa Barbara 93106.
Samuel
C E
CE
D003062:Codon; D005786:Gene Expression Regulation; D005814:Genes, Viral; D009154:Mutation; D010452:Peptide Biosynthesis; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D012087:Reoviridae / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000096:biosynthesis* / Q000235:genetics
D003062:Codon; D012333:RNA, Messenger; D012367:RNA, Viral; D011994:Recombinant Proteins; D014764:Viral Proteins