Regulation of anti-late RNA synthesis in bacteriophage T4: A delayed early control

Abstract

Bacteriophage T4 make mutually complementary RNA transcripts. The antisense RNA is made in the late region but at early times after infection. It is complementary in base sequence to late messenger RNA and, hence is called anti-late RNA. We have studied some of the physical characteristics and possible regulatory mechanisms involved in the synthesis of these unique early RNA species. Anti-late RNA sediments on 5% to 20% sucrose gradients with an average sedimentation coefficient of 20 to 22 S, comparable to that of late mRNA. The fact that anti-late synthesis becomes refractory to rifampicin before one minute after infection, suggests that it occurs from a class of immediate early promoters in the late regions. Anti-late RNA production is examined under several different conditions of altered early gene expression. In all circumstances where the delayed early gene transcription is altered, anti-late synthesis is also altered. From the data presented here, we postulate that anti-late RNA synthesis is controlled by the same mechanism as that regulating delayed early genes.