A New Class of Disordered Elements Controls DNA Replication Through Initiator Self-Assembly

Elife. 2019 Sep 27;8:e48562. doi: 10.7554/eLife.48562.

Abstract

The initiation of DNA replication in metazoans occurs at thousands of chromosomal sites known as origins. At each origin, the Origin Recognition Complex (ORC), Cdc6, and Cdt1 co-assemble to load the Mcm2-7 replicative helicase onto chromatin. Current replication models envisage a linear arrangement of isolated origins functioning autonomously; the extent of inter-origin organization and communication is unknown. Here, we report that the replication initiation machinery of D. melanogaster unexpectedly undergoes liquid-liquid phase separation (LLPS) upon binding DNA in vitro. We find that ORC, Cdc6, and Cdt1 contain intrinsically disordered regions (IDRs) that drive LLPS and constitute a new class of phase separating elements. Initiator IDRs are shown to regulate multiple functions, including chromosome recruitment, initiator-specific co-assembly, and Mcm2-7 loading. These data help explain how CDK activity controls replication initiation and suggest that replication programs are subject to higher-order levels of inter-origin organization.

Keywords: Cdc6; Cdt1; D. melanogaster; DNA replication; ORC; biochemistry; chemical biology; intrinsically disordered; phase separation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Chromatin / metabolism
  • DNA Replication*
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / genetics*
  • Origin Recognition Complex / metabolism*
  • Protein Multimerization

Substances

  • Chromatin
  • Drosophila Proteins
  • Origin Recognition Complex