The Effect of Long-Wavelenght UV on BrUra substituted E. coli: Correlation between Survival, Strand Breaks, and BrUra-Incorporation

Abstract

If normal E. coli cells are irradiated with 260 nm UV the only photonproducts are thymine dimers (

$$\mathop {TT}\limits^ \wedge $$

). Using BrUra substituted cells DNA single strand breaks are induced as well via a debromination process. Carrier and Setlow (1972) have observed that the relative efficiency per BrUra of producing single strand breaks is decreasing with increasing BrUra substitution, indicating intramolecular energy transfer. Using (313) no such energy transfer should take place, and one would expect a rather simple correlation between loss of biological function and number of strand breaks in the LNA molecule, since under these conditions the amount of

$$\mathop {TT}\limits^ \wedge $$

produced, which are lethal for the cell, is negligible.