An explanation for origin unwinding in eukaryotes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31282859.
- Also identified by DOI 10.7554/eLife.46515 and PMC identifier 6634965.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Twin CMG complexes are assembled head-to-head around duplex DNA at eukaryotic origins of replication. Mcm10 activates CMGs to form helicases that encircle single-strand (ss) DNA and initiate bidirectional forks. How the CMGs melt duplex DNA while encircling it is unknown. Here we show that <i>S. cerevisiae</i> CMG tracks with force while encircling double-stranded (ds) DNA and that in the presence of Mcm10 the CMG melts long blocks of dsDNA while it encircles dsDNA. We demonstrate that CMG tracks mainly on the 3'-5' strand during duplex translocation, predicting that head-to-head CMGs at an origin exert force on opposite strands. Accordingly, we show that CMGs that encircle double strand DNA in a head-to-head orientation melt the duplex in an Mcm10-dependent reaction.
Medical subject headings
- DNA Replication
- DNA, Fungal
- DNA, Single-Stranded
- Replication Origin