Genetic recombination between closely linked markers of bacteriophage T4. II. A mutation which reduces the formation of heteroduplex heterozygotes.

A T4 phage mutant MCO4 was isolated as a mutant that reduced the frequencies of recombinants between multiple closely-linked markers but not those between two markers. MCO4 mutation was a non-lethal, recessive mutation and was located nearby gene 24 and gene 25. MCO4 mutation reduced the frequency of heteroduplex heterozygotes but not the frequency of terminally redundant heterozygotes. Therefore, MCO4 mutation appears to block the formation and/or the extension of heteroduplex regions or to shorten their life-time.