KOPS: DNA motifs that control <em>E. coli</em> chromosome segregation by orienting the FtsK translocase
Abstract
Bacterial chromosomes are organized in replichores of opposite sequence polarity. This conserved feature suggests a role in chromosome dynamics. Indeed, sequence polarity controls resolution of chromosome dimers in Escherichia coli. Chromosome dimers form by homologous recombination between sister chromosomes. They are resolved by the combined action of two tyrosine recombinases, XerC and XerD, acting at a specific chromosomal site, dif, and a DNA translocase, FtsK, which is anchored at the division septum and sorts chromosomal DNA to daughter cells. Evidences suggest that DNA motifs oriented from the replication origin towards dif provide FtsK with the necessary information to faithfully distribute chromosomal DNA to either side of the septum, thereby bringing the dif sites together at the end of this process. However, the nature of the DNA motifs acting as FtsK orienting polar sequences (KOPS) was unknown. Using genetics, bioinformatics and biochemistry, we have identified a family of DNA motifs in the E. coli chromosome with KOPS activity.
Acknowledgments
We thank J-M Louarn for helpful discussions, M Chandler and S Kennedy for critical reading, S Schbath and S Robin for the development of the statistical tests and P Lebourgeois for technical support. S Bigot and C Lesterlin were supported by MENESR studentships. O. Saleh received a Molswitch European program fellowship. Research was supported by grants from the CNRS ATIP program, from the French research ministry Fundamental microbiology and Reactional dynamics of biological systems ACI programs, from the Young researcher ACI program and from the FRM foundation for medical research.