Repair of phage lambda DNA damaged by near ultraviolet light plus 8-methoxypsoralen.

Treatment of phage lambda with 8-methoxypsoralen plus near ultraviolet light (PUVA) and its subsequent infection and growth on various mutant and non-mutant hosts were investigated. A number of Escherichia coli DNA repair-deficient mutants, particularly those deficient in genes producing proteins known to participate in interstrand crosslink repair, were used as hosts to assess the roles of these gene products in the activation of phage affected by PUVA. Results show that puvA, uvrA, uvrD, recA, recO, sulA and recN of E. coli are involved in the repair process. Based on the data presented it is proposed that phage lambda DNA is repaired, following PUVA damage, using the recombinational repair process. This may be in agreement with the recombinational model of the repair of E. coli DNA.