This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rozsa, F. W. Articles by Arber, W. Search for Related Content PubMed PubMed Citation Articles by Rozsa, F. W. Articles by Arber, W.

 Previous Article  |  Next Article 

J. Bacteriol., 03 1995, 1159-1168, Vol 177, No. 5
Copyright © 1995, American Society for Microbiology

Cin-mediated recombination at secondary crossover sites on the Escherichia coli chromosome

FW Rozsa, P Viollier, M Fussenegger, R Hiestand-Nauer and W Arber
Department of Microbiology, University of Basel, Switzerland.

The Cin recombinase is known to mediate DNA inversion between two wild- type cix sites flanking genetic determinants for the host range of bacteriophage P1. Cin can also act with low frequency at secondary (or quasi) sites (designated cixQ) that have lower homology to either wild- type site. An inversion tester sequence able to reveal novel operon fusions was integrated into the Escherichia coli chromosome, and the Cin recombinase was provided in trans. Among a total of 13 Cin-mediated inversions studied, three different cixQ sites had been used. In two rearranged chromosomes, the breakpoints of the inversions were mapped to cixQ sites in supB and ompA, representing inversions of 109 and 210 kb, respectively. In the third case, a 2.1-kb inversion was identified at a cixQ site within the integrated sequences. This derivative itself was a substrate for a second inversion of 1.5 kb between the remaining wild-type cix and still another cixQ site, thus resembling a reversion. In analogy to that which is known from DNA inversion on plasmids, homology of secondary cix sites to wild-type recombination sites is not a strict requirement for inversion to occur on the chromosome. The chromosomal rearrangements which resulted from these Cin-mediated inversions were quite stable and suffered no growth disadvantage compared with the noninverted parental strain. The mechanistic implications and evolutionary relevance of these findings are discussed.