Bacteriophage-specific DNA-binding proteins in P22-lysogenic and in P22-infected Salmonella typhimurium

Crude extracts of Salmonella typhimurium lysogenic for phages P22 or L contain proteins that specifically retain phage DNA on nitrocellulose filters. Three DNA-binding activities were found after infection with P22. One is P22 specific, accounts for the largest proportion of DNA-binding proteins, and corresponds most likely to the c2 repressor. An early transient binding activity measured with both P22 and L DNA was found to be directly related to the expression of genes c1 and c3. A third, late binding activity for P22 and L DNA is related to phage production.