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. 2011 Sep;189(1):23–36. doi: 10.1534/genetics.111.130161

Figure 2 .

Figure 2 

UvrD action resists two RecF-dependent TLD pathways: one RecA dependent and one RecA independent. (A) RecF is partially required for much but not all of the hypersensitivity of ΔuvrD cells to TLD. A ΔuvrD ΔrecF double mutant (SMR11235; purple X) was more resistant to TLD than ΔuvrD (SMR11193; solid orange square; P < 0.05) alone, but not as resistant as ΔrecF (SMR10691; solid green triangle; P < 0.05). Parental (AB2497; solid blue diamond). (B) RecF and RecA function in independent death pathways in the absence of uvrD. The ΔuvrD ΔrecF (SMR12999; purple X) double mutant is more resistant than the ΔuvrD ΔrecA (SMR11202; open green circle; P < 0.05) mutant indicating that, in ∆uvrD cells, RecF plays a role in TLD in addition to loading RecA. The ΔuvrD ΔrecA ΔrecF triple mutant (SMR13001; open blue triangle) is as resistant to TLD as the ΔuvrD ΔrecF double mutant (P = 0.17) but is more resistant than ΔuvrD ΔrecA cells (P < 0.05). ΔuvrD (SMR11193; solid orange square), ΔrecA ΔrecF (SMR13000; solid brown circle), parental (AB2497; solid blue diamond). Data in A and B are from experiments run in parallel, thus can be compared directly. (C) recA801 partially compensates for RecF in TLD, indicating that part of the RecF role in TLD is loading of RecA. Partial suppression of the ΔrecF phenotype (SMR10691; solid green triangle) by recA801 in the ΔrecF recA801 double mutant (SMR11312; brown X; P < 0.05 compared with ∆recF). Therefore, much of the RecF role in TLD is loading RecA onto ssDNA. recA801 (SMR11310; solid pink square), parental (AB2497; solid blue diamond). The data do not exclude the additional RecA-independent role for RecF in TLD shown in B. (D) The RecA-dependent component of RecF-mediated TLD is via SOS activation. lexA(Ind−) recA801 (SMR12994; solid brown circle) cells are as resistant to TLD as lexA(Ind−) cells (epistatic, same pathway). Thus, the sole role of recA801 in TLD is promoting an SOS response. As expected lexA(Ind−) recA801 ΔrecF (SMR12992; open blue square) cells are more resistant to TLD than the lexA(Ind−) recA801 double mutant (P < 0.05, additive effects), reiterating that RecF functions in a pathway in addition to that of loading RecA and promoting SOS. lexA(Ind−) ΔrecF (SMR10692; open green circle). Parental (AB2497; solid blue diamond), recA801 (SMR11310; solid pink square), lexA(Ind−) (SMR10669; solid blue triangle). Data in C and D are from experiments run in parallel, thus can be compared directly. Means ±SEM of three independent experiments.