Identification and radiochemical purification of the recA protein of Escherichia coli K-12.

Abstract

The product of the recA gene of E. coli was identified by labeling proteins synthesized in UV-treated cells after infection with specialized .lambda. transducing phages carrying the recA gene. Following infection of UV-treated cells by .lambda.precA which carries the recA+ gene, a major protein with a MW of 43,000 is detected on polyacrylamide gels containing sodium dodecyl sulfate. This protein is also made after infection of suppressing hosts by .lambda.precA99 which carries an amber recA- mutation, but is not synthesized after infection of nonsuppressing hosts by this transducing phage. A spontaneous recA+ revertant of .lambda.precA99 induces synthesis of this protein after infection of a nonsuppressing host. The product of the recA gene is a soluble protein found in a complex with a MW of .apprx. 150,000 after mild detergent lysis of cells.