THE ROLE OF T4-BACTERIOPHAGE ENDONUCLEASE-VII IN CORRECTION OF MISMATCHED REGIONS

Recombination effects of the amber mutation E727 in gene 49, which codes for endonuclease VII (endo VII), were studied using two-and three-factor crosses of T4 bacteriophage rII mutants. Two main alterations in the recombination process, related to the absence of endo VII, were revealed: (1) basic recombination of the nonrepairable type decreased by several times; (2) differences between repairable (HR) and nonrepairable (LR) markers disappeared, and markers of both types behaved themselves as LR markers. It was concluded that endo VII recognized mismatched regions of the intermediate recombination products and performed the first stage of their reparation - single-stranded nicking.