A new class of disordered elements controls DNA replication through initiator self-assembly

• Published in: eLife Vol. 8
• Main Authors: Parker, Matthew W, Bell, Maren, Mir, Mustafa, Kao, Jonchee A, Darzacq, Xavier, Botchan, Michael R, Berger, James M
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 27.09.2019; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Animals; Binding sites; Biochemistry and Chemical Biology; Cdc6; Cdt1; Cell cycle; Chromatin; Chromatin - metabolism; Chromosomes; Communication; Deoxyribonucleic acid; DNA; DNA biosynthesis; DNA helicase; DNA Replication; Drosophila; Drosophila melanogaster - genetics; Drosophila Proteins - metabolism; Genetic aspects; Glycerol; Insects; intrinsically disordered; Metazoans; Microscopy; Observations; ORC; Organizational communication; Origin recognition complex; Origin Recognition Complex - metabolism; phase separation; Phosphorylation; Protein Multimerization; Proteins; Replication initiation; Self-assembly; United States; United States > US; Cdt1; ORC; DNA replication; phase separation; chemical biology; biochemistry; Cdc6; D. melanogaster; intrinsically disordered
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.48562

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.