Structure and Function of the Genome of Coliphage T5

Abstract

Separated strands of ligated DNA of coliphage T5 + and purified specific single‐stranded fragments were used in DNA‐RNA hybridization studies with RNA extracted from cells at various times after infection by T5 + . The ratio of the binding of pre‐early RNA to the heavy (uninterrupted) and light (nicked) strands is about 2 to 1, whereas for early RNA the ratio is about 3 to 1. Most, if not all, late RNA is transcribed from the heavy strand. Pre‐early RNA binds appreciably to a newly discovered small ( M r = 1.5 × 10 6 ) fragment of DNA derived from the light strand as well as to other, larger, fragments. The regions of transcription of the various classes of RNA are discussed in relation to a new model of the chromosome and the genetic and functional maps of T5.