The crystal structure of the N-terminal domain of the Pyrococcus furiosus
minichromosome maintenance (MCM) protein as a double hexamer is described. The
MCM complex is a ring-shaped helicase that unwinds DNA at the replication fork
of eukaryotes and archaea. Prior to replication initiation, the MCM complex
assembles as an inactive double hexamer at specific sites of DNA. The presented
structure is highly consistent with previous MCM double-hexamer structures and
shows two MCM hexamers with a head-to-head interaction mediated by the
N-terminal domain. Minor differences include a diminished head-to-head
interaction and a slightly reduced inter-hexamer rotation.
