title: DIDS, a chemical compound that inhibits RAD51-mediated homologous pairing and strand exchange.
abstract: RAD51, an essential eukaryotic DNA recombinase, promotes homologous pairing and strand exchange during homologous recombination and the recombinational repair of double strand breaks. Mutations that up- or down-regulate RAD51 gene expression have been identified in several tumors, suggesting that inappropriate expression of the RAD51 activity may cause tumorigenesis. To identify chemical compounds that affect the RAD51 activity, in the present study, we performed the RAD51-mediated strand exchange assay in the presence of 185 chemical compounds. We found that 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) efficiently inhibited the RAD51-mediated strand exchange. DIDS also inhibited the RAD51-mediated homologous pairing in the absence of RPA. A surface plasmon resonance analysis revealed that DIDS directly binds to RAD51. A gel mobility shift assay showed that DIDS significantly inhibited the DNA-binding activity of RAD51. Therefore, DIDS may bind near the DNA binding site(s) of RAD51 and compete with DNA for RAD51 binding.
authors.affiliation: Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Ishida
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takizawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kainuma
authors.forename: Jin
authors.initials: J
authors.lastname: Inoue
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Mikawa
authors.forename: Takehiko
authors.initials: T
authors.lastname: Shibata
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tashiro
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kurumizaka