MCM2-7 form double hexamers at licensed origins in Xenopus egg extract

Gambus, Agnieszka, Khoudoli, Guennadi A., Jones, Richard C. and Blow, J. Julian (2011) MCM2-7 form double hexamers at licensed origins in Xenopus egg extract. Journal of Biological Chemistry, 286 (13). pp. 11855-11864. ISSN 0021-9258

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In late mitosis and G1, Mcm2-7 are assembled onto replication origins to license them for initiation in the upcoming S phase. After initiation, Mcm2-7 provide helicase activity to unwind DNA at the replication fork. Here we examine the structure of Mcm2-7 on chromatin in Xenopus egg extracts. We show that prior to replication initiation, Mcm2-7 is present at licensed replication origins in a complex with a molecular mass close to double that of the Mcm2-7 hexamer. This complex has approximately stoichiometric quantities of the 6 Mcm2-7 proteins and we conclude that it consists of a double heterohexamer. This provides a configuration potentially capable of initiating a pair of bidirectional replication forks in S phase. We also show that after initiation, Mcm2-7 associate with Cdc45 and GINS to form a relatively stable CMG (Cdc45-MCM-GINS) complex. The CMG proteins also associate less strongly with other replication proteins, consistent with the idea that a single CMG complex forms the core of the replisome.

Item Type: Article
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Depositing User: LivePure Connector
Date Deposited: 10 Jun 2024 10:31
Last Modified: 10 Jun 2024 10:32
DOI: 10.1074/jbc.M110.199521

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