| Structural highlights
Function
[HDAC8_HUMAN] Responsible for the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4). Histone deacetylation gives a tag for epigenetic repression and plays an important role in transcriptional regulation, cell cycle progression and developmental events. Histone deacetylases act via the formation of large multiprotein complexes. May play a role in smooth muscle cell contractility.[1] [2] [3] [4]
Publication Abstract from PubMed
Histone deacetylases (HDACs) regulate cellular processes such as differentiation and apoptosis and are targeted by anticancer therapeutics in development and in the clinic. HDAC8 is a metal-dependent class I HDAC and is proposed to use a general acid-base catalytic pair in the mechanism of amide bond hydrolysis. Here, we report site-directed mutagenesis and enzymological measurements to elucidate the catalytic mechanism of HDAC8. Specifically, we focus on the catalytic function of Y306 and the histidine-aspartate dyads H142-D176 and H143-D183. Additionally, we report X-ray crystal structures of four representative HDAC8 mutants: D176N, D176N/Y306F, D176A/Y306F, and H142A/Y306F. These structures provide a useful framework for understanding enzymological measurements. The pH dependence of kcat/KM for wild-type Co(II)-HDAC8 is bell-shaped with two pKa values of 7.4 and 10.0. The upper pKa reflects the ionization of the metal-bound water molecule and shifts to 9.1 in Zn(II)-HDAC8. The H142A mutant has activity 230-fold lower than that of wild-type HDAC8, but the pKa1 value is not altered. Y306F HDAC8 is 150-fold less active than the wild-type enzyme; crystal structures show that Y306 hydrogen bonds with the zinc-bound substrate carbonyl, poised for transition state stabilization. The H143A and H142A/H143A mutants exhibit activity that is >80000-fold lower than that of wild-type HDAC8; the buried D176N and D176A mutants have significant catalytic effects, with more subtle effects caused by D183N and D183A. These enzymological and structural studies strongly suggest that H143 functions as a single general base-general acid catalyst, while H142 remains positively charged and serves as an electrostatic catalyst for transition state stabilization.
General Base-General Acid Catalysis in Human Histone Deacetylase 8.,Gantt SM Fsgm, Decroos C, Lee MS, Gullett LE, Bowman CM, Christianson DW, Fierke CA Biochemistry. 2016 Jan 25. PMID:26806311[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Hu E, Chen Z, Fredrickson T, Zhu Y, Kirkpatrick R, Zhang GF, Johanson K, Sung CM, Liu R, Winkler J. Cloning and characterization of a novel human class I histone deacetylase that functions as a transcription repressor. J Biol Chem. 2000 May 19;275(20):15254-64. PMID:10748112 doi:http://dx.doi.org/10.1074/jbc.M908988199
- ↑ Buggy JJ, Sideris ML, Mak P, Lorimer DD, McIntosh B, Clark JM. Cloning and characterization of a novel human histone deacetylase, HDAC8. Biochem J. 2000 Aug 15;350 Pt 1:199-205. PMID:10926844
- ↑ Van den Wyngaert I, de Vries W, Kremer A, Neefs J, Verhasselt P, Luyten WH, Kass SU. Cloning and characterization of human histone deacetylase 8. FEBS Lett. 2000 Jul 28;478(1-2):77-83. PMID:10922473
- ↑ Lee H, Rezai-Zadeh N, Seto E. Negative regulation of histone deacetylase 8 activity by cyclic AMP-dependent protein kinase A. Mol Cell Biol. 2004 Jan;24(2):765-73. PMID:14701748
- ↑ Gantt SM Fsgm, Decroos C, Lee MS, Gullett LE, Bowman CM, Christianson DW, Fierke CA. General Base-General Acid Catalysis in Human Histone Deacetylase 8. Biochemistry. 2016 Jan 25. PMID:26806311 doi:http://dx.doi.org/10.1021/acs.biochem.5b01327
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