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In vitro specificities of Arabidopsis co‐activator histone acetyltransferases: implications for histone hyperacetylation in gene activation
Author(s) -
Earley Keith W.,
Shook Molly S.,
BrowerToland Brent,
Hicks Leslie,
Pikaard Craig S.
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2007.03264.x
Subject(s) - histone acetyltransferases , acetylation , sap30 , histone h4 , histone h2a , histone octamer , biology , histone , histone methyltransferase , hdac4 , histone h3 , histone deacetylase 2 , hdac11 , biochemistry , microbiology and biotechnology , histone deacetylase , gene , nucleosome
Summary In genetic hybrids displaying nucleolar dominance, acetylation of lysines 5, 8, 12 and 16 of histone H4 (H4K5, H4K8, H4K12, H4K16) and acetylation of histone H3 on lysines 9 and 14 (H3K9, H3K14) occurs at the promoters of active ribosomal RNA (rRNA) genes, whereas silenced rRNA genes are deacetylated. Likewise, histone hyperacetylation correlates with the active state of transgenes and of endogenous plant genes involved in physiological processes, including cold tolerance, light‐responsiveness and flowering. To investigate histone hyperacetylation dynamics we used sodium butyrate, a histone deacetylase inhibitor known to switch silent rRNA genes on, in order to enrich the pool of acetylated histones. Mass spectrometric analyses revealed unique mono‐ (K16Ac), di‐ (K12Ac, K16Ac), tri‐ (K8Ac, K12Ac, K16Ac), and tetra‐acetylated (K5Ac, K8Ac, K12Ac, K16Ac) histone H4 isoforms, suggesting that H4 hyperacetylation occurs in a processive fashion, beginning with lysine 16 and ending with lysine 5. Using a combination of molecular and mass spectrometric assays we then determined the specificities of seven of the nine functional co‐activator type histone acetyltransferases (HATs) in Arabidopsis thaliana : specifically HATs of the CBP (HAC1, HAC5, HAC12), GNAT (HAG1, HAG2), and MYST families (HAM1, HAM2) . Specific HATs acetylate histone H4K5 (HAM1, HAM2), H4K12 (HAG2), and H3K14 (HAG1), suggesting that acetylation of these lysines may have special regulatory significance. Other acetylation events, including histone H3K9 acetylation, are likely to result from the activities of the broad‐specificity HAC1, HAC5, and HAC12 histone acetyltransferases.