Structural and functional analysis of SET8, a histone H4 Lys-20 methyltransferase

• DOI: 10.1101/gad.1318405
• Publication Date: 2005-06-03T00:34:31Z
• Authors: Jean-François Cou...; Evys Collazo; Joseph S. Brunzelle; Raymond C. Trievel
• Keywords: Models, Molecular; 0303 health sciences; Binding Sites; Protein Conformation; Static Electricity; Histone-Lysine N-Methyltransferase; In Vitro Techniques; Crystallography, X-Ray; S-Adenosylhomocysteine; Recombinant Proteins; Substrate Specificity; Histones; 03 medical and health sciences; Catalytic Domain; Mutagenesis, Site-Directed; Humans

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.