Diverged composition and regulation of the Trypanosoma brucei origin recognition complex that mediates DNA replication initiation

Marques, C. A. , Tiengwe, C., Lemgruber Soares, L. , Damasceno, J. D., Scott, A., Paape, D. , Marcello, L. and McCulloch, R. (2016) Diverged composition and regulation of the Trypanosoma brucei origin recognition complex that mediates DNA replication initiation. Nucleic Acids Research, 44(10), pp. 4763-4784. (doi: 10.1093/nar/gkw147) (PMID:26951375) (PMCID:PMC4889932)

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Initiation of DNA replication depends upon recognition of genomic sites, termed origins, by AAA+ ATPases. In prokaryotes a single factor binds each origin, whereas in eukaryotes this role is played by a six-protein origin recognition complex (ORC). Why eukaryotes evolved a multisubunit initiator, and the roles of each component, remains unclear. In Trypanosoma brucei, an ancient unicellular eukaryote, only one ORC-related initiator, TbORC1/CDC6, has been identified by sequence homology. Here we show that three TbORC1/CDC6-interacting factors also act in T. brucei nuclear DNA replication and demonstrate that TbORC1/CDC6 interacts in a high molecular complex in which a diverged Orc4 homologue and one replicative helicase subunit can also be found. Analysing the subcellular localization of four TbORC1/CDC6-interacting factors during the cell cycle reveals that one factor, TbORC1B, is not a static constituent of ORC but displays S-phase restricted nuclear localization and expression, suggesting it positively regulates replication. This work shows that ORC architecture and regulation are diverged features of DNA replication initiation in T. brucei, providing new insight into this key stage of eukaryotic genome copying.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Marcello, Dr Lucio and Paape, Dr Daniel and De Almeida Marques, Dr Catarina and Damasceno, Dr Jeziel and Scott, Mr Alan and Lemgruber Soares, Dr Leandro and McCulloch, Professor Richard
Authors: Marques, C. A., Tiengwe, C., Lemgruber Soares, L., Damasceno, J. D., Scott, A., Paape, D., Marcello, L., and McCulloch, R.
College/School:College of Medical Veterinary and Life Sciences > School of Infection & Immunity
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Nucleic Acids Research
Publisher:Oxford University Press
ISSN (Online):1362-4962
Published Online:06 March 2016
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Nucleic Acids Research 44(10):4763-4784
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
463981Characterisation of Orc1/Cdc6 and DNA replication initiation in Trypanosoma brucei.Richard McCullochWellcome Trust (WELLCOME)083485/Z/07/ZIII - PARASITOLOGY
606431Kinase dependent control of DNA replication and repair as a drug target in Trypanosoma brucei.Richard McCullochBiotechnology and Biological Sciences Research Council (BBSRC)BB/K006495/1III - PARASITOLOGY
371796The Wellcome Centre for Molecular Parasitology ( Core Support )Andrew WatersWellcome Trust (WELLCOME)085349/Z/08/ZIII - PARASITOLOGY