title: Dynamic structures of Bacillus subtilis RecN-DNA complexes.
abstract: Genetic and cytological evidences suggest that Bacillus subtilis RecN acts prior to and after end-processing of DNA double-strand ends via homologous recombination, appears to participate in the assembly of a DNA repair centre and interacts with incoming single-stranded (ss) DNA during natural transformation. We have determined the architecture of RecN-ssDNA complexes by atomic force microscopy (AFM). ATP induces changes in the architecture of the RecN-ssDNA complexes and stimulates inter-complex assembly, thereby increasing the local concentration of DNA ends. The large CII and CIII complexes formed are insensitive to SsbA (counterpart of Escherichia coli SSB or eukaryotic RPA protein) addition, but RecA induces dislodging of RecN from the overhangs of duplex DNA molecules. Reciprocally, in the presence of RecN, RecA does not form large RecA-DNA networks. Based on these results, we hypothesize that in the presence of ATP, RecN tethers the 3'-ssDNA ends, and facilitates the access of RecA to the high local concentration of DNA ends. Then, the resulting RecA nucleoprotein filaments, on different ssDNA segments, might promote the simultaneous genome-wide homology search.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma de Madrid, Darwin 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Humberto
authors.initials: H
authors.lastname: Sanchez
authors.forename: Paula P
authors.initials: PP
authors.lastname: Cardenas
authors.forename: Shige H
authors.initials: SH
authors.lastname: Yoshimura
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
authors.forename: Juan C
authors.initials: JC
authors.lastname: Alonso
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism / Q000648:ultrastructure*; D004260:DNA Repair; D004262:DNA Restriction Enzymes / Q000378:metabolism / Q000648:ultrastructure*; D004277:DNA, Single-Stranded / Q000378:metabolism / Q000648:ultrastructure*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry; D018625:Microscopy, Atomic Force; D011938:Rec A Recombinases / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases; D004262:DNA Restriction Enzymes; C047879:RecN protein, Bacteria; D015252:Deoxyribonucleases, Type II Site-Specific; C044346:GGATC-specific type II deoxyribonucleases; D008274:Magnesium