Purification and functional inactivation of the fission yeast MCM^MCM-BP complex

The MCM (mini-chromosome maintenance) complex is the core of the eukaryotic replicative helicase and comprises six proteins, Mcm2-Mcm7. In humans, a variant form of the complex has Mcm2 replaced by the MCM-BP protein. Recent results suggest that a similar complex exists in fission yeast with an essential role in DNA replication and cell cycle progression. Here, we describe the purification and subunit composition of the fission yeast MCM^Mcb1 complex. Using newly generated temperature-sensitive alleles, we show that loss of MCM^Mcb1 function leads to accumulation of DNA damage, checkpoint activation and cell cycle arrest, and provide evidence for a role for MCM^Mcb1 in meiosis.