The bacteriophage T4 regA gene: primary sequence of a translational repressor (original) (raw)

The regA gene product of bacteriophage T4 is an autogenously controlled translational regulatory protein that plays a role in differential inhibition (translational repression) of a subpopulation of T4-encoded "early" mRNA species. The structural gene for this polypeptide maps within a cluster of phage DNA replication genes, (genes 45-44-62-regA-43-42), all but one of which (gene 43) are under regA-mediated translational control. We have cloned the T4 regA gene, determine its nucleotide sequence, and identified the amino-terminal residues of a plasmid-encoded, hyperproduced regA protein. The results suggest that the T4 regA gene product is a 122 amino acid polypeptide that is mildly basic and hydrophilic in character; these features are consistent with known properties of regA protein derived from T4-infected cells. Computer-assisted analyses of e nucleotide sequences of the regA gene and its three upstream neighbors (genes 45, 44, and 62) suggest tWe existence of three translational initiation units in this four-gene cluster; one for gene 45, one for genes 44, 62 and regA, and one that serves only the egA gene. The analyses also suggest that the gene 44-62 translational unit harbors a stable RNA structure that obligates translational coupling of these two genes.