Enhanced sensitivity of Escherichia coli umuC to photodynamic inactivation by angelicin (isopsoralen).

Escherichia coli umuC cells were inactivated four times more rapidly than umuC+ cells by angelicin (a monofunctional psoralen) plus near-UV irradiation. With other DNA-damaging treatments, either no or much smaller differences in sensitivity were observed. These results show that functions associated with the UmuC+ phenotype contribute to the repair (or tolerance) of some categories of DNA damage more efficiently than others.