Klemm R D, Austin R J, Bell S P
Massachusetts Institute of Technology, Department of Biology, Cambridge 02139, USA.
Cell. 1997 Feb 21;88(4):493-502. doi: 10.1016/s0092-8674(00)81889-9.
The Origin Recognition Complex (ORC) is a six-protein assembly that specifies the sites of DNA replication initiation in S. cerevisiae. Origin recognition by ORC requires ATP. Here, we demonstrate that two subunits, Orc1p and Orc5p, bind ATP and that Orc1p also hydrolyzes ATP. ATP binding and hydrolysis by Orc1p are both regulated by origin DNA in a sequence-specific manner. ATP binding to Orc1p, but not ATP hydrolysis, is responsible for the ATP dependence of the ORC-origin interaction, indicating that ATP is a cofactor that locks ORC on origin DNA. These data demonstrate that occupancy of the Orc1p ATP-binding site has a profound effect on ORC function and that ATP hydrolysis by Orc1p has the potential to drive transitions between different functional states of ORC.
起始识别复合物（ORC）是一种由六个蛋白质组成的装配体，它指定了酿酒酵母中DNA复制起始的位点。ORC对起始位点的识别需要ATP。在此，我们证明了两个亚基Orc1p和Orc5p结合ATP，并且Orc1p还能水解ATP。Orc1p的ATP结合和水解均由起始DNA以序列特异性方式调节。ATP与Orc1p的结合而非ATP水解，是ORC与起始位点相互作用对ATP依赖性的原因，这表明ATP是将ORC锁定在起始DNA上的辅助因子。这些数据表明，Orc1p的ATP结合位点的占据对ORC功能有深远影响，并且Orc1p的ATP水解有可能驱动ORC不同功能状态之间的转变。
