DOMAINS IN HUMAN INTERFERON ALPHA-1 GENE CONTAINING TANDEMS OF ARGININE CODONS AGG PLAY THE ROLE OF TRANSLATIONAL INITIATORS IN ESCHERICHIA-COLI

The AGG and AGA are the least used arginine codons in E. coli but they are the most preferable ones in eukaryotes, The low expression of som e eucaryotic genes (such as human alpha-1 interferon gene) which conta in clusters of AGG codons is explained either by the limited pool of t he tRNA(AGG) (Varenne and Lazdunski, 1986) or by the competition of th ese clusters with the Shine-Dalgarno (SD) sequence (Ivanov et al., 199 2), The aim of the present study is to demonstrate the in vivo capacit y of AGG tandems to bind to bacterial ribosomes, The two tandems of AG G codons (Arg(12) Arg(13) and Arg(163) Arg(164)) of hIF alpha(1) with their surrounding nucleotides were cloned in a bacterial expression pl asmid containing a strong promoter and a reporter gene (chloramphenico l acetyltransferase, CAT) devoid of a ribosome binding site, The resul ts obtained showed that both AGG tandems initiated translation of the CAT mRNA with an efficiency equal to that of the consensus SD sequence and several fold higher than the native SD sequence of the CAT gene.