Role of the G segment in the growth of phage Mu

Abstract

USING the single-burst technique we have been able to show that close to one-half of the cells in a lysogenic culture of phage Mu yield no viable phage after induction. Our experiments were prompted by an intriguing observation concerning the G segment of Mu, a region of 3,000 base pairs found in either orientation in both mature phages and prophages^1,2; it is thought that G inversions are mediated by inverted repeats of approximately 50 base pairs known to be located at the two ends of G (ref. 3). It was observed that progeny phage derived from the induction of lysogenic cultures contain approximately equal numbers of particles with the G segment in either orientation, but virtually all progeny phage derived from lytic cycles of infection have their G segment in one particular orientation⁴.