MUTATIONAL ANALYSIS OF A BACTERIOPHAGE-P4 LATE PROMOTER

Transcription from the late P(sid) promoter of satellite bacteriophage P4 is dependent on the bacterial RNA polymerase carrying the sigma-70 subunit and is positively regulated by the product of the P4 delta-gene or the ogr gene of helper bacteriophage P2. Through deletion and mutational analyses of the P(sid) promoter, we identified mutations in the -10 region and in a region of hyphenated dyad symmetry centered around position -55 that inactive P(sid). Most of these mutations alter base pairs that are highly conserved in the five other delta-activated P4 and P2 late promoters. We propose that the P4 delta- and P2 ogr gene products bind the -55 region of the P4 and P2 late promoters.