Photodynamic damage and its repair in Vibrio cholerae

Abstract

Repair of photodynamic damage induced by acriflavine and visible light has been examined in three strains of Vibrio cholerae differing in their capabilities to repair ultraviolet (UV) light induced DN A damage. Excision repair deficient wild type cells of strain 154 are more sensitive to photodynamic treatment compared to repair proficient cells of strain 569B. However, no difference in their capabilities to repair of damage following photodynamic treatment can be detected. No single-strand breaks in the irradiated cell DNA are observed when the cell survival is more than 10%. Single-strand breaks observed at cell survival less than 5% are not dark repairable even in excision repair proficient wild type cells. Repair of membrane damage can partially account for the recovery observed at low doses. In contrast, radiation-sensitive mutant 569B_s cells which lack both excision and medium-dependent dark repair for UV-lesions are most efficient in repairing damage induced by photodynamic treatment.