Structure of the SET domain histone lysine methyltransferase Clr4.
Min, J., Zhang, X., Cheng, X., Grewal, S.I., Xu, R.M.(2002) Nat Struct Biol 9: 828-832
- PubMed: 12389037 
- DOI: https://doi.org/10.1038/nsb860
- Primary Citation of Related Structures:  
1MVH, 1MVX - PubMed Abstract: 
Methylation of histone H3 lysine 9 is an important component of the 'histone code' for heterochromatic gene silencing. The SET domain-containing Clr4 protein, a close relative of Su(var)3-9 proteins in higher eukaryotes, specifically methylates lysine 9 of histone H3 and is essential for silencing in Schizosaccharomyces pombe. Here we report the 2.3 A resolution crystal structure of the catalytic domain of Clr4. The structure reveals an overall fold rich in beta-strands, a potential active site consisting of a SAM-binding pocket, and a connected groove that could accommodate the binding of the N-terminal tail of histone H3. The pre-SET motif contains a triangular zinc cluster coordinated by nine cysteines distant from the active site, whereas the post-SET region is largely flexible but proximal to the active site. The structure provides insights into the architecture of SET domain histone methyltransferases and establishes a paradigm for further characterization of the Clr4 family of epigenetic regulators.
Organizational Affiliation: 
W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.