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

Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
Genes & Development (Impact Factor: 12.64). 07/2005; 19(12):1455-65. DOI: 10.1101/gad.1318405
Source: PubMed

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 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.

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    • "4E47 SAM, 0N6 a SET 1ZKK Histone 4 peptide, SAH SET [387] 2BQZ Histone 4 peptide, SAH, N-methyl-lysine SET [388] "
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    • "PR-Set7 displays robust enzymatic activity toward nucleosomal substrates, but not histone octamers or histone H4 alone. PR-Set7 was shown to be strictly a monomethyltransferase through a combination of nuclear magnetic resonance (NMR), mass spectroscopy, and in vitro experiments (Couture et al. 2005; Xiao et al. 2005). Providing further support and general insight as to how methyltransferases can be monomethyl-specific, crystallographic studies demonstrated that the substrate recognition channel of the enzyme is too narrow to accommodate a trimethylated species. "
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    • "The structures of a number of PKMTs have been reported [20] [21] [22] [23] [24] [25]. These structures collectively highlight a remarkable plasticity in the substrate/peptide binding site and lack of clear structural motifs that correlate with sequence selectivity. "
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