Refining the domain architecture model of the replication origin firing factor Treslin/TICRR.

Pedro Ferreira,Chris P Ponting,Dominik Boos,Luis Sanchez-Pulido,Anika Marko

doi:10.26508/lsa.202101088

Pedro Ferreira, Chris P Ponting + Show 3 more

Open Access

https://doi.org/10.26508/lsa.202101088

Copy DOI

Abstract

Faithful genome duplication requires appropriately controlled replication origin firing. The metazoan origin firing regulation hub Treslin/TICRR and its yeast orthologue Sld3 share the Sld3-Treslin domain and the adjacent TopBP1/Dpb11 interaction domain. We report a revised domain architecture model of Treslin/TICRR. Protein sequence analyses uncovered a conserved Ku70-homologous β-barrel fold in the Treslin/TICRR middle domain (M domain) and in Sld3. Thus, the Sld3-homologous Treslin/TICRR core comprises its three central domains, M domain, Sld3-Treslin domain, and TopBP1/Dpb11 interaction domain, flanked by non-conserved terminal domains, the CIT (conserved in Treslins) and the C terminus. The CIT includes a von Willebrand factor type A domain. Unexpectedly, MTBP, Treslin/TICRR, and Ku70/80 share the same N-terminal domain architecture, von Willebrand factor type A and Ku70-like β-barrels, suggesting a common ancestry. Binding experiments using mutants and the Sld3-Sld7 dimer structure suggest that the Treslin/Sld3 and MTBP/Sld7 β-barrels engage in homotypic interactions, reminiscent of Ku70-Ku80 dimerization. Cells expressing Treslin/TICRR domain mutants indicate that all Sld3-core domains and the non-conserved terminal domains fulfil important functions during origin firing in human cells. Thus, metazoa-specific and widely conserved molecular processes cooperate during metazoan origin firing.

Highlights

Accurate and complete DNA replication guarantees faithful genetic inheritance
Mutations of Treslin/TICRR previously showed that the MTBP/Sld7-binding M domain and the TopBP1/ Dpb11-binding TDIN perform essential functions during origin firing in human cells (Boos et al, 2011, 2013; Kumagai & Dunphy, 2017)
Our insight that Treslin/TICRR and Sld3 share similarity of the M domain (Treslin/ TICRR) and the N terminus (Sld3), respectively, completes the view that the three central domains of Treslin/TICRR, M-domain, STD, and TDIN, constitute a Sld3-like core that is flanked by two Treslin/ TICRR-specific terminal regions, the conserved in Treslins (CIT) and the C-terminal region (Fig 6)

Summary

Introduction

Accurate and complete DNA replication guarantees faithful genetic inheritance. It requires complex regulation of replication origin firing to ensure (1) efficient firing to avoid non-replicated gaps, and (2) appropriately controlled firing in space and time to facilitate the metazoan genome replication program and coordinate replication with other chromatin processes like transcription (Berezney et al, 2000; Ryba et al, 2010; Helmrich et al, 2013; Dileep et al, 2015; Petryk et al, 2016; Boos & Ferreira, 2019).Replication initiation is a two-step process in eukaryotes. Accurate and complete DNA replication guarantees faithful genetic inheritance It requires complex regulation of replication origin firing to ensure (1) efficient firing to avoid non-replicated gaps, and (2) appropriately controlled firing in space and time to facilitate the metazoan genome replication program and coordinate replication with other chromatin processes like transcription (Berezney et al, 2000; Ryba et al, 2010; Helmrich et al, 2013; Dileep et al, 2015; Petryk et al, 2016; Boos & Ferreira, 2019). Pre-RCs are first remodelled into pre-initiation complexes (pre-ICs) (Zou & Stillman, 1998; Yeeles et al, 2015; Miyazawa-Onami et al, 2017) that mature into the active Cdc45-Mcm2-7-GINS-DNA polymerase epsilon (CMGE) helicase (Ilves et al, 2010; Langston et al, 2014; Abid Ali et al, 2017; Douglas et al, 2018). DNA synthesis requires assembly of additional replisome factors and primer synthesis (Yeeles et al, 2017)

Methods

Results

Conclusion