A new suppressor of mutations in the DNA repair-recombination genes of bacteriophage T4: sur.

A new mutation designated sur was isolated as a suppressor of a mutation in the uvsX gene of T4 phage. Unlike the other suppressors of mutations in genes involved in DNA repair and recombination, sur has a wide range, suppressing both DNA repair and replication defects in mutations in genes uvsX, uvsY, 46, 47, and 59. However, its suppressor functions may be confined to the uvsX-uvsY DNA repair pathway since sur did not suppress a mutation in the denV gene. The sur mutation results in an increased degradation of host DNA to an acid-soluble form, but this increase was blocked by a mutation in gene 46 (nuclease) indicating that the sur function is involved in an earlier step in the degradation of host DNA. This increased degradation of host DNA might be a reflection of a compensatory increase in an alternate DNA repair activity in the [sur] mutant.