HOST-VIRUS INTERACTIONS IN THE CONTROL OF T4-PREREPLICATIVE TRANSCRIPTION .2. INTERACTION BETWEEN TABC (RHO) MUTANTS AND T4 MOT MUTANTS

In this paper we describe bacterial mutants (tabG) that reinforce the effect of T4 mot mutants (Mattson et al., 1978) tsG1 and amG1. tabG mutants map close to or in the Escherichia coli RNA polymerase rpoB gene. We explore the effect of mot-deficient T4 infections in tabC mutants (Caruso et al., 1979). We find that: (1) in such infections the synthesis of most T4 proteins of molecular weight greater than 24,000 is inhibited; (2) T4-specific transcription is largely restricted to those species that have been defined as immediate early. We conclude that most tabC bacterial mutants affect transcription of T4 prereplicative genes and confirm that T4 mot mutants also affect transcription of T4 prereplicative genes. We discuss a model where many (most) T4 prereplicative genes are transcribed in two alternative modes: from a rho (tabC)-sensitive, mot-independent early promoter and from a tabC-insensitive, mot-dependent, middle promoter. © 1979.