In this section
@article{Tomkins:2025,
author = {Tomkins, J and Edwardes, L and Faull, S and Peach, M and Gillespie, P and Leber, V and Schmidt, A and Bounoua, H and Nicholas, S and Camarillo, R and Blow, J and Barr, A and Barnard, A and Speck, C},
journal = {Nature Communications},
title = {Geminin inhibits DNA replication licensing by sterically blocking CDT1-MCM2 interactions},
year = {2025}
}
TY - JOUR
AB - DNA replication is tightly regulated to occur once per cell cycle, with the MCM2-7 helicase loaded onto replication origins only during G1-phase. In higher eukaryotes, geminin negatively regulates this process during S-, G2- and M-phases by binding the essential licensing factor CDT1. Although geminin’s function is crucial for genomic stability, its inhibitory mechanism remains elusive. Here, we utilise a fully reconstituted human DNA replication licensing assay to dissect geminin’s role. AlphaFold modelling provides structural insights into an N-terminal CDT1-binding helix of geminin, which proves essential for inhibition. Structural docking of the CDT1-geminin complex into the ORC-CDC6-CDT1-MCM2-7 (OCCM) assembly shows that geminin’s long coiled-coil domain sterically clashes with the MCM2 C-terminus, rather than directly blocking CDT1 binding to ORC-CDC6-MCM2-7. Shortening the coiled-coil preserves geminin dimerisation and CDT1 binding but abolishes inhibition, confirming its mechanistic role. Surprisingly, geminin is not able to fully inhibit DNA licensing. However, CDK1/2-cyclin A can partially inhibit DNA licensing and, in conjunction with geminin, result in a complete block. These findings uncover geminin’s steric inhibitory mechanism and suggest that a dual CDK-geminin axis controls human DNA replication.
AU - Tomkins,J
AU - Edwardes,L
AU - Faull,S
AU - Peach,M
AU - Gillespie,P
AU - Leber,V
AU - Schmidt,A
AU - Bounoua,H
AU - Nicholas,S
AU - Camarillo,R
AU - Blow,J
AU - Barr,A
AU - Barnard,A
AU - Speck,C
PY - 2025///
SN - 2041-1723
TI - Geminin inhibits DNA replication licensing by sterically blocking CDT1-MCM2 interactions
T2 - Nature Communications
ER -
Dr Anna Barnard
Wellcome Trust Sir Henry Dale Fellow
Department of Chemistry
Imperial College London
Wood Lane
London W12 0BZ
a.barnard@imperial.ac.uk
Tel: +44 (0)20 7594 8551