title: Chi recombination activity in phage lambda decays as a function of genetic distance.
abstract: In Escherichia coli, chi is a recombination hotspot that stimulates RecBCD-dependent exchange at and to one side of itself. chi activity is highest at chi and decreases with distance from chi. The decrease in chi activity may be a simple property of the physical distance over which chi can stimulate recombination. Alternatively, the decay in chi activity with distance may reflect the high likelihood that chi-stimulated recombination occurs in a single chi-proximal act, to the exclusion of additional chi-stimulated exchanges more distal to chi. To test the models, we determined if chi activity decreases as a function of physical distance (i.e., DNA base pairs) or genetic distance (homologous DNA base pairs). Our results indicate that chi activity decays as a function of genetic distance. In addition, we found that the sbcB gene product (exonuclease I, a 3'-->5' ssDNA exonuclease) modulates the distance over which chi can act. In contrast, the recJ gene product (a 5'-->3' ssDNA exonuclease) does not alter the decay of chi activity.
authors.affiliation: Institute of Molecular Biology, University of Oregon, Eugene 97403-1229, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Myers
authors.forename: M M
authors.initials: MM
authors.lastname: Stahl
authors.forename: F W
authors.initials: FW
authors.lastname: Stahl
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D010582:Bacteriophage lambda / Q000235:genetics*; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000378:metabolism; D008957:Models, Genetic; D011995:Recombination, Genetic; D012689:Sequence Homology, Nucleic Acid
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; D004265:DNA Helicases