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Dual initiation sites of protein synthesis on foot‐and‐mouth disease virus RNA are selected following internal entry and scanning of ribosomes in vivo.
Author(s) -
Belsham G.J.
Publication year - 1992
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1992.tb05150.x
Subject(s) - ribosome , internal ribosome entry site , biology , rna , protein biosynthesis , start codon , foot and mouth disease virus , eukaryotic translation , translation (biology) , messenger rna , genetics , gene , virus
The initiation of protein synthesis on foot‐and‐mouth disease virus RNA occurs at two sites separated by 84 nucleotides. Immediately upstream from the first of these sites is the internal ribosome entry site (IRES), which directs the translation of this RNA to be cap‐independent. The utilization of these two initiation sites has been examined using artificial fusion genes in vivo under a variety of conditions. Additional in‐frame AUG codons have been introduced between these two authentic start sites to determine the mechanism by which ribosomes recognize the second start site. The results indicate that following internal entry of ribosomes on the 5′ side of the first initiation codon, many fail to initiate protein synthesis at this position and scan along the RNA to the second initiation site. In the presence or absence of the IRES both initiation sites are efficiently used but the utilization of the two sites is slightly biased towards the second initiation site by the IRES. Furthermore, in the presence of the IRES, protein synthesis initiates at both sites independently of the activity of the cap‐binding complex.