A WD-repeat Protein Stabilizes ORC Binding to Chromatin

Mol Cell. 2010 Oct 8;40(1):99-111. doi: 10.1016/j.molcel.2010.09.021.

Abstract

Origin recognition complex (ORC) plays critical roles in the initiation of DNA replication and cell-cycle progression. In metazoans, ORC associates with origin DNA during G1 and with heterochromatin in postreplicated cells. However, what regulates the binding of ORC to chromatin is not understood. We have identified a highly conserved, leucine-rich repeats and WD40 repeat domain-containing protein 1 (LRWD1) or ORC-associated (ORCA) in human cells that interacts with ORC and modulates chromatin association of ORC. ORCA colocalizes with ORC and shows similar cell-cycle dynamics. We demonstrate that ORCA efficiently recruits ORC to chromatin. Depletion of ORCA in human primary cells and embryonic stem cells results in loss of ORC association to chromatin, concomitant reduction of MCM binding, and a subsequent accumulation in G1 phase. Our results suggest ORCA-mediated association of ORC to chromatin is critical to initiate preRC assembly in G1 and chromatin organization in post-G1 cells.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Cell Cycle
  • Cell Line, Tumor
  • Cell Proliferation
  • Chromatin Assembly and Disassembly*
  • Conserved Sequence
  • Fluorescent Antibody Technique
  • Heterochromatin / metabolism*
  • Humans
  • Immunoprecipitation
  • Microscopy, Video
  • Molecular Sequence Data
  • Mutation
  • Origin Recognition Complex / genetics
  • Origin Recognition Complex / metabolism*
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • RNA Interference
  • Recombinant Fusion Proteins / metabolism
  • Sequestosome-1 Protein
  • Time Factors
  • Transfection

Substances

  • Adaptor Proteins, Signal Transducing
  • Heterochromatin
  • Origin Recognition Complex
  • Recombinant Fusion Proteins
  • SQSTM1 protein, human
  • Sequestosome-1 Protein