Programming of DNA rearrangements involving mu prophages.

Abstract

Most of the papers in this Symposium provide abundant evidence that changes in DNA sequence organization — and, consequently, changes in the information content of DNA molecules — result from the action of specific biochemical systems. Over the past three decades, detailed in vivo and in vitro studies of how genetic changes occur have radically altered our ideas about the mutational process. Instead of invoking nonspecific chemical events, such as keto-enol tautomerism in purine and pyrimidine bases, we now see specific enzymatic activities as the agents of genetic change. Systems like the SOS response of enteric bacteria (Witkin 1976) show that genetic change is a biochemical process even when there has been direct physicochemical damage to DNA molecules. Some kinds of DNA reorganization, such as homology-dependent general recombination and replicative recombination, involve multiple biochemical steps and the activities of many proteins. There is, therefore, prima facie evidence for regulatory processes...