A tale of two genomes: resolution of dimeric chromosomes in Escherichia coli and Bacillus subtilis

Dimeric chromosomes can be formed during replication of circular bacterial chromosomes by an odd number of homologous recombination events between sis ter chromosomes. In the absence of a compensating recombination reaction su ch dimers cannot be segregated from each other as the cell divides. This re view highlights the shared and divergent mechanisms employed by Escherichia coli and Bacillus subtilis in their effort to resolve and partition dimeri c chromosomes safely. In particular, we discuss the Xer-type recombinases, RecA, FtsK/SpoIIIE, and dif. (C) 2000 Editions scientifiques et medicales E lsevier SAS.