Shapiro 9513728 "Physiological control of Mu-dependent DNA rearrangements" E. coli and Mu genetics will be used to dissect the araB-lacZ fusion system, the first rigorously documented example of physiologically-regulated mutation in bacteria ("adaptive mutation"). In this system, a Mu prophage forms a hybrid protein coding sequence by joining portions of the araB and lacA cistrons. Fusion studies using a non-lethal Mu B-KAN(7701 prophage have uncovered evidence for an activated state preceeding actual fusion formation and suggested that fusion kinetics are determined at two different levels: (1) Mu activation/derepression and (2) differential processing of the strand-transfer complex intermediate in Mu-promoted DNA rearrangements. This project will capitalize on molecular genetic technology and our ability to manipulate both the bacterial and Mu prophage genomes to accomplish two specific aims: (1) identify the nature of pre-fusion intermediates formed by thermal derepression of B-KAN(7701 strains, and (2) identify molecules in the signal transduction system controlling fusion formation. These studies will extend our understanding of how bacteria and other living cells are able to modify the structures of their genomes. In particular, it will illuminate how differences in cellular growth conditions activate and influence the natural genetic engineering systems which all organisms possess. This research will shed new light on evolutionary processes and our ability to modify cells for use in biotechnology. ***
