A Link between ORC-origin binding mechanisms and origin activation time revealed in budding yeast
Timothy Hoggard1, Erika Shor, Carolin A Müller
1Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, United States of America ; Program in Cellular and Molecular Biology, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
Plos Genetics
|September 27, 2013
Summary
The origin recognition complex (ORC) binds DNA to initiate replication. This study classifies ORC-origin interactions, revealing how chromatin influences binding and links it to DNA replication timing.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Eukaryotic DNA replication initiates at specific origins during G1 phase, involving the origin recognition complex (ORC).
- Origin firing times during S-phase are cell-type specific and crucial for genome stability and differentiation.
- The relationship between ORC-origin binding mechanisms and replication timing remains poorly understood.
Purpose of the Study:
- To classify Saccharomyces cerevisiae DNA replication origins based on ORC-binding interaction types.
- To investigate the role of DNA- versus chromatin-dependent ORC binding in origin function.
- To determine if ORC-origin binding mechanisms correlate with origin activation timing.
Main Methods:
- Genome-wide classification of origins into DNA-dependent and chromatin-dependent classes based on in vitro and in vivo ORC-binding strengths.
- Analysis of nucleosome architecture and flanking sequence dependence using plasmid replication assays.
- Correlation of origin classes with their characteristic firing times during S-phase.
Main Results:
- Origins were classified as DNA-dependent or chromatin-dependent based on ORC-binding mechanisms.
- Chromatin-dependent origins exhibited distinct nucleosome architecture and sequence dependence.
- Chromatin-dependent origins were enriched for early S-phase firing, while DNA-dependent origins were enriched for later firing.
Conclusions:
- Novel classification of replication origins based on ORC-binding mechanisms.
- Chromatin features play a significant role in ORC binding and origin selection.
- A direct link exists between ORC-origin interaction types and the regulation of DNA replication timing.
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