Polarisation of prokaryotic chromosomes.
In many prokaryotes, asymmetrical mutational or selective pressures have caused compositional skews between complementary strands of replication arms, especially sensitive in the distribution of guanine and cytosine. In Escherichia coli, most of the guanine/cytosine skew is caused by mutation rates differing on leading and lagging strands, but contribution of skewed functionally important guanine-rich motifs (Chi and Rag sites), which control chromosome repair or positioning, is noticeable. Interference between replication and gene expression plays a minor role. The situation may be different in other bacteria. Studies of chromosome processing and bacterial taxonomy might profit from consideration of chromosome polarisation.
Lobry
Jean R
JR
Laboratoire de Biométrie et Biologie évolutive, CNRS UMR 5558, Université Claude Bernard, 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne cedex, France. lobry@biomserv.univ-lyon1.fr
Louarn
Jean-Michel
JM
D001482:Base Composition; D002876:Chromosomes, Bacterial / Q000737:chemistry / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D019143:Evolution, Molecular; D008957:Models, Genetic