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

Recombination effects of the amber mutation E727 in gene 49, which cod es for endonuclease VII (endo VII), were studied using two-and three-f actor crosses of T4 bacteriophage rII mutants. Two main alterations in the recombination process, related to the absence of endo VII, were r evealed: (1) basic recombination of the nonrepairable type decreased b y several times; (2) differences between repairable (HR) and nonrepair able (LR) markers disappeared, and markers of both types behaved thems elves as LR markers. It was concluded that endo VII recognized mismatc hed regions of the intermediate recombination products and performed t he first stage of their reparation - single-stranded nicking.