Organization and function of bacteriophage T4 tail. I. Isolation of heat-sensitive T4 tail mutants.

Abstract

Abstract Phage T4 mutants which produce viral particles more sensitive to heating at 55°C than the wild type T4 have been isolated. They map in T4 tail genes 5, 6, 7, 10, 12, 18, 25, 27, and 48. According to the types of morphological alterations of the heat-inactivated particles, they were classified into three groups: 1. A: genes 5 and 12. No obvious change. 2. B: genes 18, 25, and 48. Sheath contracts, but baseplate is left. 3. C: genes 6, 7, 10, 25, and 27. Baseplate attached to the contracted sheath. Heat-sensitivities of Type C mutants only were suppressed by the presence of indole, whereas lower pH suppressed every mutants including Type A and Type B mutants. Heat-inactivated gene 5 mutant particles contract their sheath when mixed with the host cells, whereas gene 12 inactive phage remained unchanged. The analyses of heat-sensitive mutants may identify functional interactions between proteins in the phage particle.