Nucleotide sequences involved in bacteriophage T4 gene 32 translational self-regulation.

Abstract

The nucleotide sequence of a cloned segment of the bacteriophage T4D chromosome, which contains the regulatory sequences and the structural gene (gene 32) for the single-stranded DNA binding protein (gp32), was determined. The amino acid sequence predicted by translation of the structural gene agreees well with that published for gp32. To localize the nucleotide sequence involved in translational self-regulation of gene 32, a series of plasmids were constructed in which gene 32 is fused to an amino-terminal deletion mutant of the .beta.-galactosidase gene of Escherichia coli. Expression of a .beta.-galactosidase fusion protein that contains only the first 7 amino acids of gp32 is still repressed by gp32. The ribosomal binding site of gene 32 is flanked by a repetitive A + T-rich sequence. Preferential and cooperative binding of gp32 to this region of its mRNA could inhibit translation initiation and, thus, would account for the autoregulation.