Control of lysogenization by phage P22. II. Mutations (clyA) in the cl gene that cause increased lysogenization.

(Received 10 NovembPr IYSO, and in revised form 24 April 19X1) p12 cly mutants lysogenize at very high frequency after infection of wild-type Salmonella. One class of P22 cly mutations, clyA mutations, are shown to map within the P22 cl gene and to increase the activity of t,he cl gene product during establishment of lysogeny. The P22 clyil mutations also appear to affect c%-repressor gene expression in cis and to cause a Cro-phenotype, despite the fart) that the cZyA mutations map far downstream (with respect to transcription) of the end of the l'Z2 cm gene.