P22 antirepressor protein prevents in vivo recA-dependent proteolysis of P22 repressor

Abstract

A method was developed to demonstrate recA-dependent P22-repressor breakdown in vivo by SDS-polyacrylamide electrophoresis of unfractionated extracts of phage-infected, lysogenic Salmonella typhimurium strains TA1530 rec+ and TA1530 recA1-. The antirepressor of P22 is not cleaved by recA protein. Under conditions of unregulated ant-overproduction (Harvey et al. 1981) antirepressor protects c2-repressor in vivo against proteolytic cleavage by recA protein.

Separating Functions of the Phage-Encoded Quorum-Sensing-Activated Antirepressor Qtip

“…Strikingly, early work on phage P22 showed that an Ant-overproducing P22 mutant that was exposed to UV light to induce RecA-dependent autoproteolysis did not undergo autoproteolysis, which is unlike a similarly treated non-Ant-overproducing P22 prophage (Prell and Harvey, 1983). This experiment suggested that Ant production ''protects'' C2 from autoproteolysis (Prell and Harvey, 1983). The experiment did not address whether the effect was direct or indirect.…”

“…cI VP882 and P22 C2 are curious in this regard because both possess autoproteolytic activity and are subject to inactivation by antirepressors (Qtip and Ant, respectively). Strikingly, early work on phage P22 showed that an Ant-overproducing P22 mutant that was exposed to UV light to induce RecA-dependent autoproteolysis did not undergo autoproteolysis, which is unlike a similarly treated non-Ant-overproducing P22 prophage (Prell and Harvey, 1983). This experiment suggested that Ant production ''protects'' C2 from autoproteolysis (Prell and Harvey, 1983).…”

Bacteriophage lambda: Early pioneer and still relevant

“…The first of these to be discovered was the P22 antirepressor (Ant), which binds to repressor and causes it to release repression (Susskind and Botstein, 1975). Transcription of the ant gene in a prophage is kept off by two additional phage-encoded repressors, Mnt and Arc, and a small antisense RNA, Sar, that controls the translation of ant mRNA (Prell and Harvey, 1983; Liao et al , 1987; Wu et al , 1987; Schaefer and McClure, 1997). Salmonella lambdoid phage gifsy-1 encodes an antirepressor GfoR that is repressed by the host LexA repressor (Lemire et al , 2011).…”

Separating Functions of the Phage-Encoded Quorum-Sensing-Activated Antirepressor Qtip

“…showed that an Ant-overproducing P22 mutant that was exposed to UV light to induce RecAdependent autoproteolysis did not undergo autoproteolysis, which is unlike a similarly treated non-Ant-overproducing P22 prophage (Prell and Harvey, 1983). This experiment suggested that Ant production "protects" C2 from autoproteolysis (Prell and Harvey, 1983). The experiment did not address whether the effect was direct or indirect.…”