DSSR-PyMOL cartoon-block schematics: PDB entry 4pog

PDB-id

4pog; DSSR-derived features in text and JSON formats

Class

replication, DNA binding protein-DNA

Method

X-ray (3.203 Å)

Summary

Mcm-ssDNA co-crystal structure

Reference

Froelich CA, Kang S, Epling LB, Bell SP, Enemark EJ (2014): "A conserved MCM single-stranded DNA binding element is essential for replication initiation." Elife, 3, e01993. doi: 10.7554/eLife.01993.

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.