Role of ATP in Excision Repair of Ultraviolet Radiation Damage in Escherichia coli

Abstract

The effect of ATP on the first step of excision repair of ultraviolet damage in DNA has been studied using toluene-treated E. coli. During postirradiation incubation, five to six times more single-strand breaks are formed in DNA in the presence of exogenous ATP than in its absence. The ATP-dependent as well as the ATP-independent endonucleolytic activities appear to be catalyzed by the same enzyme since both activities are almost completely absent in uvrA and uvrB mutants. An ATP-dependent endonucleolytic activity has been detected in nonirradiated toluene-treated E. coli. It is concluded that ATP is required in vivo for either the incision step of repair or an enzymatic reaction preceding it.