Process of Infection with Bacteriophage øX174: XXIII. DNA Synthesis in Cells infected by a Coat Protein Mutant

Abstract

Single-stranded progeny DNA is not formed when host cells are infected at the restrictive temperature with a temperature-sensitive coat protein mutant of øX174. Once begun, the synthesis of single-stranded DNA is interrupted when an infected culture is shifted from the permissive to the restrictive temperature. The synthesis of double-stranded “replicative form” DNA is observed under restrictive conditions. Upon shifting an infected culture from restrictive to permissive conditions after 30 minutes of infection, single-stranded DNA synthesis starts almost immediately. In this instance, the initial single-stranded viral DNA is formed out of the pre-formed double-stranded replicative form DNA by degradation of the complementary strand. The attachment of coat protein to the viral strand and the release of the viral strand from the double-stranded precursor appear to take place simultaneously.