title: Identification of the RecA protein-loading domain of RecBCD enzyme.
abstract: Genetic recombination in Escherichia coli is stimulated by the recombination hotspot Chi (chi), a regulatory element that modifies the activities of the RecBCD enzyme and leads to loading of the DNA strand exchange protein, RecA, onto the chi-containing DNA strand. The RecBC enzyme, which lacks the RecD subunit, loads RecA protein constitutively, in a manner that is independent of chi. Using a truncated RecBC enzyme lacking the 30 kDa C-terminal domain of the RecB subunit, we show that this domain is necessary for RecA protein-loading. We propose that this domain harbors a site that interacts with RecA protein, recruiting it to single-stranded DNA during unwinding. This ability of a translocating enzyme to deliver material (RecA protein) to a specific target site (the chi sequence) parallels that of other cellular motor proteins.
authors.affiliation: Section of Microbiology, Graduate Group in Biochemistry, University of California, Davis, CA, 95616, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Churchill
authors.forename: S C
authors.initials: SC
authors.lastname: Kowalczykowski
mesh_terms: D020029:Base Pairing / Q000235:genetics; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding; D011938:Rec A Recombinases / Q000378:metabolism*; D011995:Recombination, Genetic / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D020035:Holoenzymes; D011938:Rec A Recombinases; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli; D004265:DNA Helicases