Control of gene expression in the P2-related template coliphages

Abstract

The PstI fragment (65.5% to 77.4%) of coliphage 186, known genetically to encode the major control genes, has been sequenced, and an analysis performed to assess coding capacity, transcription-translation signals, and to identify any other significant features. Our analysis indicates that the region encodes: (1) seven genes, including the int and cI genes, which overlap, the late control gene B, and two genes, named CP75 and CP76, encoding potential DNA-binding proteins; (2) a promoter pB and terminator tB for the rightward transcription of the B gene, and we predict the existence of this transcript in a lysogen; (3) a promoter pL and terminator tL for leftward transcription that encodes the int and cI genes, and represents the presumed lysogenic transcript; (4) a promoter pR for rightward transcription to give the presumed (early) lytic transcript that is overlapping and convergent with the lysogenic transcript; and finally (5), a potential operator site for repressor binding in the region of the pR promoter. Preliminary evidence is presented to support this analysis.