How a disordered linker in the Polycomb protein Polyhomeotic tunes phase separation and oligomerization.

Autor:	Gemeinhardt TM; Montreal Clinical Research Institute (IRCM), Montreal, QC, Canada.; Division of Experimental Medicine, McGill University, Montreal, QC, Canada., Regy RM; Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA., Mendiola AJ; Department of Biochemistry and Molecular Genetics, Midwestern University, Glendale, AZ, USA., Ledterman HJ; Department of Biochemistry and Molecular Genetics, Midwestern University, Glendale, AZ, USA., Henrickson A; Department of Chemistry and Biochemistry, The University of Lethbridge, Lethbridge, AB, Canada., Phan TM; Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA., Kim YC; Center for Materials Physics and Technology, Naval Research Laboratory, Washington, DC 20375, USA., Demeler B; Department of Chemistry and Biochemistry, The University of Lethbridge, Lethbridge, AB, Canada.; Department of Chemistry, University of Montana, Missoula, MT, United States., Kim CA; Department of Biochemistry and Molecular Genetics, Midwestern University, Glendale, AZ, USA., Mittal J; Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.; Department of Chemistry, Texas A&M University, College Station, TX, USA.; Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, TX, USA., Francis NJ; Montreal Clinical Research Institute (IRCM), Montreal, QC, Canada.; Division of Experimental Medicine, McGill University, Montreal, QC, Canada.; Department of Biochemistry and Molecular Medicine, University of Montreal, Montreal, QC, Canada.
Jazyk:	angličtina
Zdroj:	BioRxiv : the preprint server for biology [bioRxiv] 2023 Oct 27. Date of Electronic Publication: 2023 Oct 27.
DOI:	10.1101/2023.10.26.564264
Abstrakt:	The Polycomb Group (PcG) complex PRC1 represses transcription, forms condensates in cells, and modifies chromatin architecture. These processes are connected through the essential, polymerizing Sterile Alpha Motif (SAM) present in the PRC1 subunit Polyhomeotic (Ph). In vitro , Ph SAM drives formation of short oligomers and phase separation with DNA or chromatin in the context of a Ph truncation ("mini-Ph"). Oligomer length is controlled by the long disordered linker (L) that connects the SAM to the rest of Ph--replacing Drosophila PhL with the evolutionarily diverged human PHC3L strongly increases oligomerization. How the linker controls SAM polymerization, and how polymerization and the linker affect condensate formation are not know. We analyzed PhL and PHC3L using biochemical assays and molecular dynamics (MD) simulations. PHC3L promotes mini-Ph phase separation and makes it relatively independent of DNA. In MD simulations, basic amino acids in PHC3L form contacts with acidic amino acids in the SAM. Engineering the SAM to make analogous charge-based contacts with PhL increased polymerization and phase separation, partially recapitulating the effects of the PHC3L. Ph to PHC3 linker swaps and SAM surface mutations alter Ph condensate formation in cells, and Ph function in Drosophila imaginal discs. Thus, SAM-driven phase separation and polymerization are conserved between flies and mammals, but the underlying mechanisms have diverged through changes to the disordered linker. Competing Interests: Declaration of interests The authors declare no competing interests.
Databáze:	MEDLINE
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