1peg: Difference between revisions

[[Image:1peg.gif|left|200px]]<br /><applet load="1peg" size="350" color="white" frame="true" align="right" spinBox="true"  

DIM-5 is a SUV39-type histone H3 Lys9 methyltransferase that is essential for DNA methylation in N. crassa. We report the structure of a ternary complex including DIM-5, S-adenosyl-L-homocysteine, and a substrate H3 peptide. The histone tail inserts as a parallel strand between two DIM-5 strands, completing a hybrid sheet. Three post-SET cysteines coordinate a zinc atom together with Cys242 from the SET signature motif (NHXCXPN) near the active site. Consequently, a narrow channel is formed to accommodate the target Lys9 side chain. The sulfur atom of S-adenosyl-L-homocysteine, where the transferable methyl group is to be attached in S-adenosyl-L-methionine, lies at the opposite end of the channel, approximately 4 A away from the target Lys9 nitrogen. Structural comparison of the active sites of DIM-5, an H3 Lys9 trimethyltransferase, and SET7/9, an H3 Lys4 monomethyltransferase, allowed us to design substitutions in both enzymes that profoundly alter their product specificities without affecting their catalytic activities.

1PEG is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Neurospora_crassa Neurospora crassa] with <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=SAH:'>SAH</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Histone-lysine_N-methyltransferase Histone-lysine N-methyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.1.43 2.1.1.43] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PEG OCA].  

[[Category: Horton, J R.]]

[[Category: Khan, S I.]]

[[Category: Selker, E U.]]

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