An Inactive Geminin Mutant That Binds Cdt1

Genes

Marissa Suchyta²  Benoit Miotto¹  Thomas J. McGarry² 

[1] Epigenetics and Cell Fate, Sorbonne Paris Cité, University Paris Diderot, UMR 7216 CNRS, Paris 75013, France; E-Mail:;Department of Medicine, Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University Chicago, IL 60610, USA; E-Mail:

关键词: DNA replication;    pre-replication complex;    Cdt1;    geminin;    HBO1;   

DOI  :  10.3390/genes6020252

来源: mdpi

【 摘 要 】

The initiation of DNA replication is tightly regulated in order to ensure that the genome duplicates only once per cell cycle. In vertebrate cells, the unstable regulatory protein Geminin prevents a second round of DNA replication by inhibiting the essential replication factor Cdt1. Cdt1 recruits mini-chromosome maintenance complex (MCM2-7), the replication helicase, into the pre-replication complex (pre-RC) at origins of DNA replication. The mechanism by which Geminin inhibits MCM2-7 loading by Cdt1 is incompletely understood. The conventional model is that Geminin sterically hinders a direct physical interaction between Cdt1 and MCM2-7. Here, we describe an inactive missense mutant of Geminin, Geminin^AWA, which binds to Cdt1 with normal affinity yet is completely inactive as a replication inhibitor even when added in vast excess. In fact, Geminin^AWA can compete with Geminin^WT for binding to Cdt1 and prevent it from inhibiting DNA replication. Geminin^AWA does not inhibit the loading of MCM2-7 onto DNA in vivo, and in the presence of Geminin^AWA, nuclear DNA is massively over-replicated within a single S phase. We conclude that Geminin does not inhibit MCM loading by simple steric interference with a Cdt1-MCM2-7 interaction but instead works by a non-steric mechanism, possibly by inhibiting the histone acetyltransferase HBO1.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.