David Dressler

Mechanism of replication of phi-X-174 single stranded DNA.

Progeny single stranded DNA seems to arise by displacement of plus strand material from precursor RF-type molecules during the asymmetric synthesis of new plus strand material.

The DNA Replication Cycle of the Isometric Phages

It is just twenty years since Robert Sinsheimer reported the results of his initial studies on a small and previously uncharacterized virus, ϕ X174. It is one of the ironies of research that a virus initially so different and odd should gradually emerge as a system offering some of the deepest insights into a major area of molecular biology, DNA replication. In contrast to the disruptive entrance into the host cell of larger viruses such as T4 and T7, bacteriophage ϕ X and the related isometric phage G4 set to work quietly, not disturbing the host cell except for an eventual cessation of bacterial DNA synthesis (Tessman 1966; Stone 1970). Even in the midst of this seeming order, however, the virus diverts the host sufficiently to generate a thousandfold replication of itself—a process which is readily observed if one studies a mutant virus that does not lyse the host prematurely. The host cell supplies almost all of the enzymatic machinery required for the viral DNA replication cycle. It is precisely for this reason that the single-stranded (SS) DNA phages are able to serve as a window into the DNA replication apparatus of Escherichia coli. The way in which the viral chromosome is processed during its replication reveals the reaction mechanisms of many host enzymes that normally play a role in bacterial DNA synthesis but which are commandeered by the virus after infection. In this article we will consider the various steps in the ϕ X and G4 replication cycles and discuss the...

Preface/Front Matter

The single-stranded DNA phages are among the smallest organisms known. They have been tremendously valuable in elucidating several fundamental life processes, especially DNA replication and gene organization. Indeed, overlapping genes were discovered in single-stranded phages. This book is based on an international meeting held at Cold Spring Harbor in August 1977 and contains a comprehensive and up-to-date account of what is known about the life process of the single-stranded phages. The meeting was made possible by generous support from the National Science Foundation and from the Cold Spring Harbor Laboratory. The tireless efforts of Nancy Ford are responsible for seeing the production of this volume through to its completion. Without the encouragement of Dr. James D. Watson the book would not have been attempted.