MCM-BP regulates unloading of the MCM2-7 helicase in late S phase

Genes Dev. 2011 Jan 15;25(2):165-75. doi: 10.1101/gad.614411. Epub 2010 Dec 31.

Abstract

Origins of DNA replication are licensed by recruiting MCM2-7 to assemble the prereplicative complex (pre-RC). How MCM2-7 is inactivated or removed from chromatin at the end of S phase is still unclear. Here, we show that MCM-BP can disassemble the MCM2-7 complex and might function as an unloader of MCM2-7 from chromatin. In Xenopus egg extracts, MCM-BP exists in a stable complex with MCM7, but is not associated with the MCM2-7 hexameric complex. MCM-BP accumulates in nuclei in late S phase, well after the loading of MCM2-7 onto chromatin. MCM-BP immunodepletion in Xenopus egg extracts inhibits replication-dependent MCM dissociation without affecting pre-RC formation and DNA replication. When excess MCM-BP is incubated with Xenopus egg extracts or immunopurified MCM2-7, it binds to MCM proteins and promotes disassembly of the MCM2-7 complex. Recombinant MCM-BP also releases MCM2-7 from isolated late-S-phase chromatin, but this activity is abolished when DNA replication is blocked. MCM-BP silencing in human cells also delays MCM dissociation in late S phase. We propose that MCM-BP plays a key role in the mechanism by which pre-RC is cleared from replicated DNA in vertebrate cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carrier Proteins / metabolism
  • Cell Cycle Proteins / metabolism
  • Cell Nucleus / metabolism
  • Chromatin / metabolism
  • Chromosomal Proteins, Non-Histone / metabolism*
  • DNA Helicases / metabolism*
  • Gene Silencing
  • HeLa Cells
  • Humans
  • Minichromosome Maintenance Complex Component 2
  • Protein Binding
  • Protein Transport
  • RNA, Small Interfering / metabolism
  • S Phase / physiology*
  • Xenopus Proteins / metabolism*

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • MCMBP protein, Xenopus
  • RNA, Small Interfering
  • Xenopus Proteins
  • DNA Helicases
  • Mcm2 protein, Xenopus
  • Minichromosome Maintenance Complex Component 2