Model of action of UvrD/uvrD252 in replication mutants (adapted from reference 18). At dnaN(Ts)-blocked forks (right portion), UvrD252 is unable to counteract RecQJFORA, and we propose that UvrD acts by removing RecA from DNA. At dnaE(Ts)-blocked (13) and rep-blocked (this work) forks, UvrD252 can counteract RecQJFORA, and we propose that it acts prior to RecA binding, by preventing it. RarA is shown in parentheses because it is only essential for RecA binding in the dnaE(Ts) mutant and not in the rep mutant. RuvAB is the only way of RFR in the dnaE(Ts) mutant and one of two pathways in the rep mutant. In the dnaN(Ts) mutant, RFR is RuvAB independent and the enzymes that reverse forks are unknown (1).