Thymineless death and its relation to UV sensitivity in Escherichia coli.

Abstract

Thymineless death in various strains of E. coli was examined and compared with sensitivity to UV irradiation and mitomycin (MC) treatment; E. coli B, a strain ultrasensitive to UV and MC, displayed a new unexpected sensitivity to thymine deprivation. Instead of the usual delayed response to thymine starvation, death commenced immediately and at an exponential rate about twice that ultimately obtained in B/r. Thymineless death in UV-and MC-ultrasensitive strains of E. coli K12 proceeded with the usual lag of about 50 min. before the onset of cell death. A single defect in (DNA) repair cannot satisfactorily account for both ultrasensitivity to thymineless death and ultrasensitivity to either UV or MC.