title: Comparison of activity of OsDmc1A recombinase of rice (Oryza sativa) in presence of Ca2+ and Mg2+ ions.
abstract: Recombinases are known to play an important role in the homology search and strand exchange during meiosis as well as homologous recombination (HR)-mediated DNA repair specifically require Mg2+ ion for their activity. The Ca2+ has been shown to stimulate the strand exchange activity of hDmc1 and ScDmc1 by forming the extended filaments on DNA. Oryza sativa disrupted meiotic cDNA1A (OsDmc1A), a homologue of yeast and human Dmc1 from rice shows the hallmark functions of recombinase. Here, we report the effects of Ca2+ and Mg2+ on OsDmc1A activity from rice (Oryza sativa). OsDmc1A showed a concentration-dependent binding with both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) substrates in presence of Mg2+ or Ca2+. The ssDNA and dsDNA binding activities, as well as renaturation activity of OsDmc1A were similar in the presence of Ca2+ or Mg2+. Increasing the Ca2+ or Mg2+ increased the DNA binding, renaturation and strand exchange of OsDmc1A. But, OsDmc1A showed only a slight stimulation of strand exchange activity in presence of Ca2+, when compared the activity in presence of Mg2+. Electron microscopy showed that OsDmc1A formed ring-like structures in presence of Mg2+ or Ca2+. However, OsDmc1A formed filament like structures with both ss and dsDNA in presence of Mg2+ or Ca2+. Taken together, Ca2+ did not affect OsDmc1A recombinase activity significantly.
authors.forename: Rajani Kant
authors.initials: RK
authors.lastname: Chittela
authors.forename: Michael
authors.initials: M
authors.lastname: Melzer
authors.forename: Jayashree Krishna
authors.initials: JK
authors.lastname: Sainis
mesh_terms: D002118:Calcium / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology*; D045522:Recombinases / Q000378:metabolism*
chemical_list: D045522:Recombinases; D008274:Magnesium; D002118:Calcium