title: Filament formation and robust strand exchange activities of the rice DMC1A and DMC1B proteins.
abstract: The DMC1 protein, a meiosis-specific DNA recombinase, catalyzes strand exchange between homologous chromosomes. In rice, two Dmc1 genes, Dmc1A and Dmc1B, have been reported. Although the Oryza sativa DMC1A protein has been partially characterized, however the biochemical properties of the DMC1B protein have not been defined. In the present study, we expressed the Oryza sativa DMC1A and DMC1B proteins in bacteria and purified them. The purified DMC1A and DMC1B proteins formed helical filaments along single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and promoted robust strand exchange between ssDNA and dsDNA over five thousand base pairs in the presence of RPA, as a co-factor. The DMC1A and DMC1B proteins also promoted strand exchange in the absence of RPA with long DNA substrates containing several thousand base pairs. In contrast, the human DMC1 protein strictly required RPA to promote strand exchange with these long DNA substrates. The strand-exchange activity of the Oryza sativa DMC1A protein was much higher than that of the DMC1B protein. Consistently, the DNA-binding activity of the DMC1A protein was higher than that of the DMC1B protein. These biochemical differences between the DMC1A and DMC1B proteins may provide important insight into their functional differences during meiosis in rice.
authors.affiliation: Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, 513 Wasedatsurumaki-cho, Shinjuku-ku, Tokyo 162-0041, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Sakane
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kamataki
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takizawa
authors.forename: Marina
authors.initials: M
authors.lastname: Nakashima
authors.forename: Seiichi
authors.initials: S
authors.lastname: Toki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ichikawa
authors.forename: Shukuko
authors.initials: S
authors.lastname: Ikawa
authors.forename: Takehiko
authors.initials: T
authors.lastname: Shibata
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000595:Amino Acid Sequence; D004247:DNA / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology*; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D045522:Recombinases / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D016415:Sequence Alignment
chemical_list: D010940:Plant Proteins; D045522:Recombinases; D004247:DNA; D000251:Adenosine Triphosphatases