Structural and functional analysis of SET8, a histone H4 Lys-20 methyltransferase.
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 beta-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.
Couture
Jean-François
JF
Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
Collazo
Evys
E
Brunzelle
Joseph S
JS
Trievel
Raymond C
RC
D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D055672:Static Electricity; D013379:Substrate Specificity
D006657:Histones; D011994:Recombinant Proteins; D012435:S-Adenosylhomocysteine; D011495:Histone-Lysine N-Methyltransferase; C470730:KMT5A protein, human