Inactive T4 progeny virus formation in a temperature-sensitive mutant of Escherichia coli K12

Abstract

We describe a mutant (W22) of Escherichia coli K12 W3350 in which viable T-even phage production is temperature sensitive. The uninfected bacterium is indistinguishable from the wild-type parental strain at both low and high temperatures. We show by electron microscopical observations and in vitro complementation that at the nonpermissive temperature viral particles are produced that are unable to infect a T4-sensitive host because of a functional defect in the tail fibers. The rest of the particle is normal and can be activated by incubation with fiber containing extracts. Necessary and sufficient for the expression of temperature sensitivity is the synthesis of early bacteriophage products at the nonpermissive temperature. We suggest that a host protein is involved in viral morphogenesis.