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#H2A-H2B dimers

2 public questions tagged with this topic.

Regulation of chromatin structure

Which histone chaperone mainly handles H2A-H2B dimers?

Histone chaperones coordinate stepwise deposition of octamer components behind replication fork and at repair sites. NAP1 family members preferentially bind H2A-H2B dimers through acidic C-terminal domain, shielding positively charged surfaces and preventing non-specific DNA interactions. Structural data show NAP1 dimer holds one H2A-H2B dimer, delivering it to tetrasome to complete nucleosome assembly, and also extracts dimers during disassembly. In contrast, CAF-1 and ASF1 handle H3-H4. NAP1 also participates in H2A variant exchange, importin-mediated nuclear import and modulation of remodel

Ref: Mosammaparast et al., PNAS, NAP1 Histone Chaperone Handles H2A-H2B Dimers, Assembly Mechanism

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Regulation of chromatin structure

Which nucleosome remodeling action removes H2A-H2B dimers?

Nucleosome remodeling encompasses sliding, ejection, dimer exchange and loop formation driven by ATP-dependent complexes. Dimer exchange specifically replaces canonical H2A-H2B dimers with variants like H2A.Z or H2A.X without complete octamer disassembly. SWR1 and INO80 complexes mediate this reaction through ATP-driven distortion of DNA at superhelical location 2, transiently opening dimer-tetramer interface and swapping in variant dimer from chaperone-bound pool. This mechanism establishes specialized chromatin domains at promoters and damage sites, altering nucleosome stability and recruitm

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 9: Chromatin Remodeling Complexes, Dimer Exchange

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