Mechanism of Replication of φX174 Single-Stranded DNA IX. Requirement for the Escherichia coli dnaG Protein

Abstract

Escherichia coli NY73, possessing a temperature-sensitive mutation in the dnaG locus, was rendered sensitive to bacteriophage φX174 by P1 transduction. φX174 reproduces in this strain at 30 C but not at 40 C. All three stages of φX174 replication, parental replicative form (RF) synthesis, RF replication, and progeny single-stranded DNA synthesis, are thermolabile in this mutant. Competition-annealing data show that both plus- and minus-strand synthesis are equally inhibited after shift up to 40 C during RF replication. We conclude that the dnaG gene product is required for the synthesis of both strands of φX RF during RF replication and of the complementary strand and viral progeny strands during stages I and III, respectively.