TABLE 2.

Comparison of the RE values of inter-HN2-pTZSV28 and C-pTZSV28 in different E. coli strains to determine a role for DNA Pol II in interstrand cross-link repair^a

Strainb	Genotypec	Plasmidd	RE in expt no.:						RRE (avg)e
			1	2	3	4	5	6
FC40	Wild type		0.64	0.51	0.57	0.60	0.59	0.67	1.00
C600	Wild type		0.56	0.58					1.00
AB1157	Wild type			0.71					1.00
PFB60	ΔpolB		0.094	0.126	0.11	0.10	0.087	0.13	0.18
SC301	ΔpolB		0.100	0.096					0.17
PFB50	uvrA6					0.043	0.022		0.055
BH200	uvrA::Tn10			0.024					0.034
PFB175	ΔpolB uvrA6						0.017		0.028
FC40	Wild type	pBIP			0.56			0.58	1.00
PFB60	ΔpolB	pBIP			0.12			0.17	0.26
FC40	Wild type	pHC206 (polB+)			0.66			0.65	1.00
PFB60	ΔpolB	pHC206 (polB+)			0.57			0.71	0.98

^aInter-HN2-pTZSV28 contains a single nitrogen mustard interstrand cross-link. Inter-HN2-pTZSV28 or its non-cross-link-containing control (C-pTZSV28) was transformed (electroporation) in parallel in triplicate into each of the indicated strains and then plated in duplicate on ampicillin-containing plates. One day later the numbers of ampicillin-resistant colonies were determined, and the average of the six plates for each point was calculated. The RE is defined as the ratio of ampicillin-resistant colonies: [inter-HN2-pTZSV28]/[C-pTZSV28]. 

^bStrain name (see Table 1). 

^cRelevant genotype (see Table 1). Mutant strains are paired as follows: FC40 and PFB60, PFB50, or PFB175; C600 and SC301; and AB1157 and BH200. 

^dPlasmid name (see Table 1). 

^eRRE is defined as follows: (RE in a repair-deficient strain)/(RE in a repair-proficient strain) (see text). Values for the RRE are based on the average for all of the relevant experiments.