1. Identification of ORC1/CDC6-Interacting Factors in Trypanosoma brucei Reveals Critical Features of Origin Recognition Complex Architecture
- Author
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Richard Burchmore, J. David Barry, Lucio Marcello, Helen Farr, Calvin Tiengwe, Stephen D. Bell, Richard McCulloch, Catarina Gadelha, and Nieduszynski, CA
- Subjects
General Science & Technology ,Protein subunit ,Molecular Sequence Data ,Trypanosoma brucei brucei ,Origin Recognition Complex ,lcsh:Medicine ,Cell Cycle Proteins ,Sequence alignment ,Trypanosoma brucei ,Biochemistry ,Microbiology ,DNA replication factor CDT1 ,03 medical and health sciences ,Nucleic Acids ,Molecular Cell Biology ,parasitic diseases ,MD Multidisciplinary ,Amino Acid Sequence ,lcsh:Science ,ORC1 ,Biology ,Phylogeny ,030304 developmental biology ,Genetics ,0303 health sciences ,Multidisciplinary ,biology ,Chromosome Biology ,lcsh:R ,030302 biochemistry & molecular biology ,DNA Helicases ,DNA replication ,Helicase ,DNA ,Genomics ,biology.organism_classification ,Protein Subunits ,biology.protein ,Origin recognition complex ,lcsh:Q ,RNA Interference ,Protein Multimerization ,Sequence Alignment ,Cell Division ,Research Article ,Protein Binding - 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.
- Published
- 2012