Genetic requirements for hyper-recombination by very short patch mismatch repair: involvement of Escherichia coli DNA polymerase I.

It has been established that very short patch (VSP) mismatch repair, depending in Escherichia coli on MutL, MutS and Dcm functions, is responsible for the hyper-recombinogenic effect of a class of genetic markers. We show that VSP repair requires the presence of the complete DNA polymerase I enzyme. The absence of endonuclease activities involved in the repair of base-loss sites, Nth, Nfo and Xth, does not affect VSP repair. Implications for the mechanism of the VSP repair are discussed.