Activation of the MCM2-7 Helicase by Association With Cdc45 and GINS Proteins

Mol Cell. 2010 Jan 29;37(2):247-58. doi: 10.1016/j.molcel.2009.12.030.

Abstract

MCM2-7 proteins provide essential helicase functions in eukaryotes at chromosomal DNA replication forks. During the G1 phase of the cell cycle, they remain loaded on DNA but are inactive. We have used recombinant methods to show that the Drosophila MCM2-7 helicase is activated in complex with Cdc45 and the four GINS proteins (CMG complex). Biochemical activities of the MCM AAA+ motor are altered and enhanced through such associations: ATP hydrolysis rates are elevated by two orders of magnitude, helicase activity is robust on circular templates, and affinity for DNA substrates is improved. The GINS proteins contribute to DNA substrate affinity and bind specifically to the MCM4 subunit. All pairwise associations among GINS, MCMs, and Cdc45 were detected, but tight association takes place only in the CMG. The onset of DNA replication and unwinding may thus occur through allosteric changes in MCM2-7 affected by the association of these ancillary factors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Animals
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism*
  • DNA / metabolism
  • DNA Replication
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / metabolism*
  • Drosophila Proteins / physiology
  • Drosophila melanogaster / enzymology*
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / metabolism
  • Enzyme Activation
  • Models, Biological
  • Molecular Sequence Data
  • Sequence Alignment

Substances

  • Cdc45 protein, Drosophila
  • Cell Cycle Proteins
  • Drosophila Proteins
  • Adenosine Triphosphate
  • DNA