Identification of ORC1/CDC6-Interacting Factors in Trypanosoma brucei Reveals Critical Features of Origin Recognition Complex Architecture
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Published version
Author(s)
Type
Journal Article
Abstract
DNA Replication initiates by formation of a pre-replication complex on sequences termed origins. In eukaryotes, the pre-
replication complex is composed of the Origin Recognition Complex (ORC), Cdc6 and the MCM replicative helicase in
conjunction with Cdt1. Eukaryotic ORC is considered to be composed of six subunits, named Orc1–6, and monomeric Cdc6
is closely related in sequence to Orc1. However, ORC has been little explored in protists, and only a single ORC protein,
related to both Orc1 and Cdc6, has been shown to act in DNA replication in
Trypanosoma brucei
. Here we identify three
highly diverged putative
T. brucei
ORC components that interact with ORC1/CDC6 and contribute to cell division. Two of
these factors are so diverged that we cannot determine if they are eukaryotic ORC subunit orthologues, or are parasite-
specific replication factors. The other we show to be a highly diverged Orc4 orthologue, demonstrating that this is one of
the most widely conserved ORC subunits in protists and revealing it to be a key element of eukaryotic ORC architecture.
Additionally, we have examined interactions amongst the
T. brucei
MCM subunits and show that this has the conventional
eukaryotic heterohexameric structure, suggesting that divergence in the
T. brucei
replication machinery is limited to the
earliest steps in origin licensing.
replication complex is composed of the Origin Recognition Complex (ORC), Cdc6 and the MCM replicative helicase in
conjunction with Cdt1. Eukaryotic ORC is considered to be composed of six subunits, named Orc1–6, and monomeric Cdc6
is closely related in sequence to Orc1. However, ORC has been little explored in protists, and only a single ORC protein,
related to both Orc1 and Cdc6, has been shown to act in DNA replication in
Trypanosoma brucei
. Here we identify three
highly diverged putative
T. brucei
ORC components that interact with ORC1/CDC6 and contribute to cell division. Two of
these factors are so diverged that we cannot determine if they are eukaryotic ORC subunit orthologues, or are parasite-
specific replication factors. The other we show to be a highly diverged Orc4 orthologue, demonstrating that this is one of
the most widely conserved ORC subunits in protists and revealing it to be a key element of eukaryotic ORC architecture.
Additionally, we have examined interactions amongst the
T. brucei
MCM subunits and show that this has the conventional
eukaryotic heterohexameric structure, suggesting that divergence in the
T. brucei
replication machinery is limited to the
earliest steps in origin licensing.
Editor(s)
Nieduszynski, Conrad A
Date Issued
2012-03-08
Date Acceptance
2012-02-02
Citation
PLoS ONE, 2012, 7 (3)
ISSN
1932-6203
Publisher
Public Library of Science (PLoS)
Journal / Book Title
PLoS ONE
Volume
7
Issue
3
Copyright Statement
© 2012 Tiengwe et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Subjects
MD Multidisciplinary
General Science & Technology
Publication Status
Published
OA Location
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3297607/pdf/pone.0032674.pdf
Article Number
e32674
Date Publish Online
2012-03-08