FIGURE 1.

TLS bypass of THF and CPD lesions by polymerases on oligonucleotide primer templates. The indicated concentrations of DNA polymerases were incubated with the CPD ([5′-³²P]CG18:CG17CPD), THF ([5′-³²P]CG18:CG17THF), and undamaged ([5′-³²P]CG18:CG16) primer templates for 10 min at 37 °C, and the DNA products were processed and analyzed as described under “Experimental Procedures.” The white asterisks correspond to the position of the CPD or THF lesion, accordingly, in the template strand. P denotes the position of the unextended primer. The extent of bypass (mean and standard deviation from three experiments) is given as the percentage of total radioactivity in extended primer species. Representative gels are shown. A, Pol IV bypasses both a THF and CPD lesion. B, Pol II bypasses a THF, but not a CPD, lesion. C, Pol III* does not bypass either a THF or CPD lesion. D, inactivation of the 3′ → 5′ proofreading exonuclease of Pol II stimulates TLS. E, Pol IV ΔC5, but not Pol IV F13V, bypasses a CPD lesion. F, Pol IV ΔC5, but not Pol IV F13V, bypasses a THF lesion. G, Pol IV F13V is active on an undamaged primer template. H, Pol IV L1 (LF domain variant) is active in TLS. Representative gels are shown.