Abstract
The inheritance of parental histones across the replication fork is thought to mediate epigenetic memory. Here, we reveal that fission yeast Mrc1 (CLASPIN in humans) binds H3-H4 tetramers and operates as a central coordinator of symmetric parental histone inheritance. Mrc1 mutants in a key connector domain disrupted segregation of parental histones to the lagging strand comparable to Mcm2 histone-binding mutants. Both mutants showed clonal and asymmetric loss of H3K9me-mediated gene silencing. AlphaFold predicted co-chaperoning of H3-H4 tetramers by Mrc1 and Mcm2, with the Mrc1 connector domain bridging histone and Mcm2 binding. Biochemical and functional analysis validated this model and revealed a duality in Mrc1 function: disabling histone binding in the connector domain disrupted lagging-strand recycling while another histone-binding mutation impaired leading strand recycling. We propose that Mrc1 toggles histones between the lagging and leading strand recycling pathways, in part by intra-replisome co-chaperoning, to ensure epigenetic transmission to both daughter cells.
Original language | English |
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Pages (from-to) | 5029-5047.e21 |
Journal | Cell |
Volume | 187 |
Issue number | 18 |
DOIs | |
Publication status | Published - 05 Sept 2024 |
Keywords
- Histones/metabolism
- Schizosaccharomyces/metabolism
- Epigenesis, Genetic
- Schizosaccharomyces pombe Proteins/metabolism
- DNA Replication
- Cell Cycle Proteins/metabolism
- Mutation
- Epigenetic Memory