Inactivation and proteolytic cleavage of phage lambda repressor in vitro in an ATP-dependent reaction.

We have reproduced in vitro the inactivation of bacteriophage lambda repressor that occurs in vivo when a lambda lysogen is treated with agents such as ultraviolet radiation that attack DNA. ATP and a divalent cation are required for the inactivation reaction. The ind- repressor is insensitive to the inactivation mechanism. A proteolytic cleavage of repressor accompanies inactivation in vitro, as it does in vivo.