A conserved MCM single-stranded DNA binding element is essential for replication initiation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 24692448.
- Also identified by DOI 10.7554/eLife.01993 and PMC identifier 3970758.
- 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
The ring-shaped MCM helicase is essential to all phases of DNA replication. The complex loads at replication origins as an inactive double-hexamer encircling duplex DNA. Helicase activation converts this species to two active single hexamers that encircle single-stranded DNA (ssDNA). The molecular details of MCM DNA interactions during these events are unknown. We determined the crystal structure of the Pyrococcus furiosus MCM N-terminal domain hexamer bound to ssDNA and define a conserved MCM-ssDNA binding motif (MSSB). Intriguingly, ssDNA binds the MCM ring interior perpendicular to the central channel with defined polarity. In eukaryotes, the MSSB is conserved in several Mcm2-7 subunits, and MSSB mutant combinations in S. cerevisiae Mcm2-7 are not viable. Mutant Mcm2-7 complexes assemble and are recruited to replication origins, but are defective in helicase loading and activation. Our findings identify an important MCM-ssDNA interaction and suggest it functions during helicase activation to select the strand for translocation. DOI: http://dx.doi.org/10.7554/eLife.01993.001.
Medical subject headings
- Conserved Sequence
- DNA Replication
- DNA, Single-Stranded
- Minichromosome Maintenance Proteins