title: Identification of DNA motifs implicated in maintenance of bacterial core genomes by predictive modeling.
abstract: Bacterial biodiversity at the species level, in terms of gene acquisition or loss, is so immense that it raises the question of how essential chromosomal regions are spared from uncontrolled rearrangements. Protection of the genome likely depends on specific DNA motifs that impose limits on the regions that undergo recombination. Although most such motifs remain unidentified, they are theoretically predictable based on their genomic distribution properties. We examined the distribution of the "crossover hotspot instigator," or Chi, in Escherichia coli, and found that its exceptional distribution is restricted to the core genome common to three strains. We then formulated a set of criteria that were incorporated in a statistical model to search core genomes for motifs potentially involved in genome stability in other species. Our strategy led us to identify and biologically validate two distinct heptamers that possess Chi properties, one in Staphylococcus aureus, and the other in several streptococci. This strategy paves the way for wide-scale discovery of other important functional noncoding motifs that distinguish core genomes from the strain-variable regions.
authors.affiliation: INRA, UR888, Unité des Bactéries Lactiques et pathogènes Opportunistes, Jouy en Josas, France.
authors.forename: David
authors.initials: D
authors.lastname: Halpern
authors.forename: Hélène
authors.initials: H
authors.lastname: Chiapello
authors.forename: Sophie
authors.initials: S
authors.lastname: Schbath
authors.forename: Stéphane
authors.initials: S
authors.lastname: Robin
authors.forename: Christelle
authors.initials: C
authors.lastname: Hennequet-Antier
authors.forename: Alexandra
authors.initials: A
authors.lastname: Gruss
authors.forename: Meriem
authors.initials: M
authors.lastname: El Karoui
mesh_terms: D001419:Bacteria / Q000235:genetics; D001483:Base Sequence; D003434:Crossing Over, Genetic; D004269:DNA, Bacterial / Q000235:genetics*; D016680:Genome, Bacterial; D008957:Models, Genetic; D011995:Recombination, Genetic
chemical_list: D004269:DNA, Bacterial