title: AFM studies on the role of the protein RdgC in bacterial DNA recombination.
abstract: Genetic studies of rdgC in different bacterial systems suggest that it may play a role in replication and recombination. However, the exact function of the corresponding protein, RdgC, is unknown. In this study, we have imaged complexes of RdgC with both linear and supercoiled circular plasmid DNA using atomic force microscopy. We confirm that RdgC does not target any specific sequences in double-stranded DNA, as has been suggested from biochemical data. However, we detect an increased affinity of the protein to DNA ends, and an ability to promote bending of DNA. Similar binding preferences have been reported for enzymes involved in recombination. Protein complexes with supercoiled plasmid DNA further enabled us to study the effect of RdgC on DNA superstructure. At high concentrations of protein we observed promotion of DNA condensation. Recombination is largely enhanced by close contacts of distant regions along the DNA strands, as can occur, for instance, through condensation. Our data thus support a possible function of RdgC as a midwife of recombination.
authors.affiliation: Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Tessmer
authors.forename: Timothy
authors.initials: T
authors.lastname: Moore
authors.forename: Robert G
authors.initials: RG
authors.lastname: Lloyd
authors.forename: Anna
authors.initials: A
authors.lastname: Wilson
authors.forename: Dorothy A
authors.initials: DA
authors.lastname: Erie
authors.forename: Stephanie
authors.initials: S
authors.lastname: Allen
authors.forename: Saul J B
authors.initials: SJ
authors.lastname: Tendler
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D020836:Protein Structure, Quaternary; D011995:Recombination, Genetic
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; C103478:RdgC protein, E coli