Structural and functional analysis of SET8, a histone H4 Lys-20 methyltransferase
Abstract
SET8 (also known as PR-SET7) is a histone H4-Lys-20-specific methyltransferase that is implicated in cell-cycle-dependent transcriptional silencing and mitotic regulation in metazoans. Herein we report the crystal structure of human SET8 (hSET8) bound to a histone H4 peptide bearing Lys-20 and the product cofactor S-adenosylhomocysteine. Histone H4 intercalates in the substrate-binding cleft as an extended parallel β-strand. Residues preceding Lys-20 in H4 engage in an extensive array of salt bridge, hydrogen bond, and van der Waals interactions with hSET8, while the C-terminal residues bind through predominantly hydrophobic interactions. Mutational analysis of both the substrate-binding cleft and histone H4 reveals that interactions with residues in the N and C termini of the H4 peptide are critical for conferring substrate specificity. Finally, analysis of the product specificity indicates that hSET8 is a monomethylase, consistent with its role in the maintenance of Lys-20 monomethylation during cell division.
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Article published online ahead of print. Article and publication date are at http://www.genesdev.org/cgi/doi/10.1101/gad.1318405.
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↵3 Corresponding author. E-MAIL rtrievel{at}umich.edu; FAX (734) 763-4581.
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- Accepted May 2, 2005.
- Received March 25, 2005.
- Cold Spring Harbor Laboratory Press