Binding and Partial Denaturing of G-quartet DNA by Cdc13p of Saccharomyces cerevisiae

Abstract The protein Cdc13p binds telomeres in vivo and is essential for the maintenance of the telomeres ofSaccharomyces cerevisiae. In addition, Cdc13p is known to bind single-stranded TG1–3 DNA in vitro. Here we have shown that Cdc13p also binds DNA quadruplex, G-quartet, formed by TG1–3 DNA. Moreover, the binding of Cdc13p causes a partial denaturing of the G-quartet DNA. Formation of DNA quadruplexes may involve the intermolecular association of TG1–3 DNA and inhibit the extension of telomeres by telomerase. Thus, our finding suggests that Cdc13p may disrupt telomere association and facilitate telomere replication.