title: Calcium ion promotes yeast Dmc1 activity via formation of long and fine helical filaments with single-stranded DNA.
abstract: Dmc1 is specifically required for homologous recombination during meiosis. Here we report that the calcium ion enabled Dmc1 from budding yeast to form regular helical filaments on single-stranded DNA (ssDNA) and activate its strand assimilation activity. Relative to magnesium, calcium increased the affinity of Dmc1 for ATP and but reduces its DNA-dependent ATPase activity. These effects, together with previous studies of other RecA-like recombinases, support the view that ATP binding to Dmc1 protomers is required for functional filament structure. The helical pitch of the Saccharomyces cerevisiae Dmc1-ssDNA helical filament was estimated to be 13.4 +/- 2.5 nm. Analysis of apparently "complete" Dmc1-ssDNA filaments indicated a stoichiometry of 24 +/- 2 nucleotides per turn of the Dmc1 helix. This finding suggests that the number or protomers per helical turn and/or the number of nucleotides bound per Dmc1 protomer differs from that reported previously for Rad51 and RecA filaments. Our data support the view that the active form of Dmc1 protein is a helical filament rather than a ring. We speculate that Ca(2+) plays a significant role in regulating meiotic recombination.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Lee
authors.forename: Yuan-Chih
authors.initials: YC
authors.lastname: Chang
authors.forename: Eurie L
authors.initials: EL
authors.lastname: Hong
authors.forename: Jennifer
authors.initials: J
authors.lastname: Grubb
authors.forename: Chia-Seng
authors.initials: CS
authors.lastname: Chang
authors.forename: Douglas K
authors.initials: DK
authors.lastname: Bishop
authors.forename: Ting-Fang
authors.initials: TF
authors.lastname: Wang
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D010584:Bacteriophage phi X 174 / Q000235:genetics; D002118:Calcium / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D002413:Cations, Divalent; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D015636:Magnesium Chloride / Q000494:pharmacology; D018625:Microscopy, Atomic Force; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D002413:Cations, Divalent; D018797:Cell Cycle Proteins; C513033:DMC1 protein, S cerevisiae; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D015636:Magnesium Chloride; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D002122:Calcium Chloride; D002118:Calcium