8qyv
SWR1-hexasome complex
Structural highlights
FunctionH2A1_YEAST Core component of nucleosome which plays a central role in DNA double strand break (DSB) repair. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.[1] [2] [3] [4] Publication Abstract from PubMedThe yeast SWR1 complex catalyzes the exchange of histone H2A/H2B dimers in nucleosomes with Htz1/H2B dimers. We use cryoelectron microscopy to determine the structure of an enzyme-bound hexasome intermediate in the reaction pathway of histone exchange, in which an H2A/H2B dimer has been extracted from a nucleosome prior to the insertion of a dimer comprising Htz1/H2B. The structure reveals a key role for the Swc5 subunit in stabilizing the unwrapping of DNA from the histone core of the hexasome. By engineering a crosslink between an Htz1/H2B dimer and its chaperone protein Chz1, we show that this blocks histone exchange by SWR1 but allows the incoming chaperone-dimer complex to insert into the hexasome. We use this reagent to trap an SWR1/hexasome complex with an incoming Htz1/H2B dimer that shows how the reaction progresses to the next step. Taken together the structures reveal insights into the mechanism of histone exchange by SWR1 complex. Stabilization of the hexasome intermediate during histone exchange by yeast SWR1 complex.,Jalal ASB, Girvan P, Chua EYD, Liu L, Wang S, McCormack EA, Skehan MT, Knight CL, Rueda DS, Wigley DB Mol Cell. 2024 Aug 28:S1097-2765(24)00669-5. doi: 10.1016/j.molcel.2024.08.015. PMID:39226902[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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