Host genes involved in the replication of single-stranded DNA phage phiK.

Using various replication mutants of E. coli, the host genes that participate in the replication of some K12-specific single-stranded DNA phages have been determined. Functional products of dnaE, -F, -G and -Z genes are required for the multiplication of phiK, whereas dnaA, -B, -C(D), H, -I and -P are dispensable for viral replication. In contrast with polB, recA, B, C, or xth functions, host rep activity is essential for phiK. At the restrictive temperature, the yield of phiK was markedly reduced in the ligts7 mutant and partially decreased in a polAts strain. The phage phiK is thus less dependent on the host cells than phiX174 and phiA which require additionally the dnaB, -C(D) and -H functions. Replication of phage St-1 depends on dnaG and -Z gene products, but not on dnaP function. Although not much affected in polAts host, growth of St-1 was significantly diminished in dnaF or ligts7 mutants.