Gene 49 endonuclease VII is not essential for multiplicity reactivation of bacteriophage T4.

Endonuclease VII, the product of phage T4 gene 49, has been shown previously to resolve Holliday structures in vitro. Two different processes, genetic recombination and multiplicity reactivation are presumed to have Holliday structure intermediates. Other workers have shown that genetic recombination is reduced in a gene 49 mutant infection. However, in the present study, multiplicity reactivation of UV-irradiated ts or amber mutant phage defective in gene 49 was nearly identical to that of UV-irradiated wild-type phage T4. Thus endonuclease VII is not thought to be essential for multiplicity reactivation of phage T4.