title: Bacillus subtilis DprA recruits RecA onto single-stranded DNA and mediates annealing of complementary strands coated by SsbB and SsbA.
abstract: Naturally transformable bacteria recombine internalized ssDNA with a homologous resident duplex (chromosomal transformation) or complementary internalized ssDNAs (plasmid or viral transformation). Bacillus subtilis competence-induced DprA, RecA, SsbB, and SsbA proteins are involved in the early processing of the internalized ssDNA, with DprA physically interacting with RecA. SsbB and SsbA bind and melt secondary structures in ssDNA but limit RecA loading onto ssDNA. DprA binds to ssDNA and facilitates partial dislodging of both single-stranded binding (SSB) proteins from ssDNA. In the absence of homologous duplex DNA, DprA does not significantly increase RecA nucleation onto protein-free ssDNA. DprA facilitates RecA nucleation and filament extension onto SsbB-coated or SsbB plus SsbA-coated ssDNA. DprA facilitates RecA-mediated DNA strand exchange in the presence of both SSB proteins. DprA, which plays a crucial role in plasmid transformation, anneals complementary strands preferentially coated by SsbB to form duplex circular plasmid molecules. Our results provide a mechanistic framework for conceptualizing the coordinated events modulated by SsbB in concert with SsbA and DprA that are crucial for RecA-dependent chromosomal transformation and RecA-independent plasmid transformation.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain.
authors.forename: Tribhuwan
authors.initials: T
authors.lastname: Yadav
authors.forename: Begoña
authors.initials: B
authors.lastname: Carrasco
authors.forename: James
authors.initials: J
authors.lastname: Hejna
authors.forename: Yuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
authors.forename: Juan C
authors.initials: JC
authors.lastname: Alonso
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D055162:Biocatalysis; D002876:Chromosomes, Bacterial; D004277:DNA, Single-Stranded / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D011485:Protein Binding; D011938:Rec A Recombinases / Q000378:metabolism*; D011995:Recombination, Genetic
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; C093815:DprA protein, bacteria; D008565:Membrane Proteins; D011938:Rec A Recombinases
keywords: DNA Recombination; DNA Transformation; DNA-binding Protein; Gene Transfer; Homologous Recombination; RecA; RecO; SSbA