Human histone acetyltransferase HAT1 preferentially acetylates H4 molecules in H3.1-H4 dimers over H3.3-H4 dimers.

In mammalian cells, canonical histone H3 (H3.1) and H3 variant (H3.3) differ by five amino acids and are assembled, along with histone H4, into nucleosomes via distinct nucleosome assembly pathways. H3.1-H4 molecules are assembled by histone chaperone CAF-1 in a replication-coupled process, whereas H3.3-H4 are assembled via HIRA in a ...
replication-independent pathway. Newly synthesized histone H4 is acetylated at lysine 5 and 12 (H4K5, 12) by histone acetyltransferase 1 (HAT1). However, it remains unclear whether HAT1 and H4K5, 12ac differentially regulate these two nucleosome assembly processes. Here, we show that HAT1 binds and acetylates H4 in H3.1-H4 molecules preferentially over H4 in H3.3-H4. Depletion of Hat1, the catalytic subunit of HAT1 complex, results in reduced H3.1 occupancy at H3.1 enriched genes and reduced association of Importin 4 with H3.1, but not H3.3. Finally, depletion of Hat1 or CAF-1p150 leads to changes in expression of a H3.1 enriched gene. These results indicate that HAT1 differentially impacts nucleosome assembly of H3.1-H4 and H3.3-H4.
Date: Jan. 07, 2012
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