Phage λ DNA injection into Escherichia coli pel− mutants is restored by mutations in phage genes V or H

Abstract

Escherichia coli pel − mutants block the growth of phage λ by inhibiting DNA injection. λ hp mutants regain the ability to inject into pel − hosts. Most λ hp mutants are not temperature sensitive. All such mutants analyzed (15 independent mutants) lie within gene H. A few percent of the λ hp mutants are temperature sensitive; at 42° they grow neither on pel + nor on pel − hosts. Reversion studies suggest that the hp and the temperature-sensitive phenotypes are due to the same mutation. The λ hpts phage particles are heat stable and inject their DNA at 42°. The thermolabile step appears to be expressed late in infection, during phage assembly. Genetic mapping places all λ hpts mutants tested (13 independent mutants) in gene V. Our data indicate that the major λ phage tail protein V and the minor tail protein H play a role in DNA injection.