Structural mechanism of helicase loading onto replication origin DNA by ORC-Cdc6.

ABSTRACT: DNA replication origins serve as sites of replicative helicase loading. In all eukaryotes, the six-subunit origin recognition complex (Orc1-6; ORC) recognizes the replication origin. During late M-phase of the cell-cycle, Cdc6 binds to ORC and the ORC-Cdc6 complex loads in a multistep reaction and, with the help of Cdt1, the core Mcm2-7 helicase onto DNA. A key intermediate is the ORC-Cdc6-Cdt1-Mcm2-7 (OCCM) complex in which DNA has been already inserted into the central channel of Mcm2-7. Until now, it has been unclear how the origin DNA is guided by ORC-Cdc6 and inserted into the Mcm2-7 hexamer. Here, we truncated the C-terminal winged-helix-domain (WHD) of Mcm6 to slow down the loading reaction, thereby capturing two loading intermediates prior to DNA insertion in budding yeast. In "sem

SUBMITTER: Yuan Z 

PROVIDER: S-EPMC7395460 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature