1. A new class of disordered elements controls DNA replication through initiator self-assembly.
- Author
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Parker, Matthew W, Bell, Maren, Mir, Mustafa, Kao, Jonchee A, Darzacq, Xavier, Botchan, Michael R, and Berger, James M
- Subjects
Chromatin ,Animals ,Drosophila melanogaster ,Drosophila Proteins ,DNA Replication ,Origin Recognition Complex ,Protein Multimerization ,Cdc6 ,Cdt1 ,D. melanogaster ,DNA replication ,ORC ,biochemistry ,chemical biology ,intrinsically disordered ,phase separation ,Biochemistry and Cell Biology - 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.
- Published
- 2019