4psw
From Proteopedia
Revision as of 14:42, 4 August 2016
Crystal structure of histone acetyltransferase complex
Structural highlights
Function[HAT1_YEAST] Catalytic component of the histone acetylase B (HAT-B) complex. Acetylates 'Lys-12' of free histone H4 in the cytoplasm. The complex is also found in the nucleus, however it is not certain that it modifies histone H4 when packaged in chromatin. Histone H4 'Lys-12' acetylation is required for telomeric silencing. Has intrinsic substrate specificity that modifies lysine in recognition sequence GXGKXG. Involved in DNA double-strand break repair.[1] [2] [3] [4] [5] [V8PGJ1_OPHHA] Core component of nucleosome. 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 (By similarity).[SAAS:SAAS001951_004_106348][RuleBase:RU000528] [HAT2_YEAST] Regulatory subunit of the histone acetylase B (HAT-B) complex. The complex acetylates 'Lys-12' of histone H4 which is required for telomeric silencing. HAT2 is required for high affinity binding of the acetyltransferase to histone H4, for the nuclear location of HAT1 and for the HAT1-HIF1 interaction. Alone, it is unable to bind to H4, requiring HAT1 for high affinity interaction with the histone tail. HAT2 has also a HAT1 independent function in life-span regulation.[6] [7] [8] [9] Publication Abstract from PubMedPost-translational modifications of histones are significant regulators of replication, transcription, and DNA repair. Particularly, newly synthesized histone H4 in H3/H4 heterodimers becomes acetylated on N-terminal lysine residues prior to its incorporation into chromatin. Previous studies have established that the histone acetyltransferase (HAT) complex Hat1p/Hat2p medicates this modification. However, the mechanism of how Hat1p/Hat2p recognizes and facilitates the enzymatic activities on the newly assembled H3/H4 heterodimer remains unknown. Furthermore, Hat2p is a WD40 repeat protein, which is found in many histone modifier complexes. However, how the WD40 repeat proteins facilitate enzymatic activities of histone modification enzymes is unclear. In this study, we first solved the high-resolution crystal structure of a Hat1p/Hat2p/CoA/H4 peptide complex and found that the H4 tail interacts with both Hat1p and Hat2p, by which substrate recruitment is facilitated. We further discovered that H3 N-terminal peptides can bind to the Hat2p WD40 domain and solved the structure of the Hat1p/Hat2p/CoA/H4/H3 peptide complex. Moreover, the interaction with Hat2p requires unmodified Arg2/Lys4 and Lys9 on the H3 tail, suggesting a novel model to specify the activity of Hat1p/Hat2p toward newly synthesized H3/H4 heterodimers. Together, our study demonstrated the substrate recognition mechanism by the Hat1p/Hat2p complex, which is critical for DNA replication and other chromatin remodeling processes. Hat2p recognizes the histone H3 tail to specify the acetylation of the newly synthesized H3/H4 heterodimer by the Hat1p/Hat2p complex.,Li Y, Zhang L, Liu T, Chai C, Fang Q, Wu H, Agudelo Garcia PA, Han Z, Zong S, Yu Y, Zhang X, Parthun MR, Chai J, Xu RM, Yang M Genes Dev. 2014 Jun 1;28(11):1217-27. doi: 10.1101/gad.240531.114. Epub 2014 May , 16. PMID:24835250[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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