title: The Escherichia coli DinD protein modulates RecA activity by inhibiting postsynaptic RecA filaments.
abstract: Escherichia coli dinD is an SOS gene up-regulated in response to DNA damage. We find that the purified DinD protein is a novel inhibitor of RecA-mediated DNA strand exchange activities. Most modulators of RecA protein activity act by controlling the amount of RecA protein bound to single-stranded DNA by affecting either the loading of RecA protein onto DNA or the disassembly of RecA nucleoprotein filaments bound to single-stranded DNA. The DinD protein, however, acts postsynaptically to inhibit RecA during an on-going DNA strand exchange, likely through the disassembly of RecA filaments. DinD protein does not affect RecA single-stranded DNA filaments but efficiently disassembles RecA when bound to two or more DNA strands, effectively halting RecA-mediated branch migration. By utilizing a nonspecific duplex DNA-binding protein, YebG, we show that the DinD effect is not simply due to duplex DNA sequestration. We present a model suggesting that the negative effects of DinD protein are targeted to a specific conformational state of the RecA protein and discuss the potential role of DinD protein in the regulation of recombinational DNA repair.
authors.affiliation: Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003, USA.
authors.forename: Lee A
authors.initials: LA
authors.lastname: Uranga
authors.forename: Victoria D
authors.initials: VD
authors.lastname: Balise
authors.forename: Candice V
authors.initials: CV
authors.lastname: Benally
authors.forename: Angelina
authors.initials: A
authors.lastname: Grey
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Lusetti
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D013014:SOS Response, Genetics / Q000502:physiology*
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D029968:Escherichia coli Proteins; C087483:dinD protein, E coli; D011938:Rec A Recombinases