2ddr: Difference between revisions

[[Image:2ddr.gif|left|200px]]<br /><applet load="2ddr" size="350" color="white" frame="true" align="right" spinBox="true"  

Sphingomyelinase (SMase) from Bacillus cereus (Bc-SMase) hydrolyzes sphingomyelin to phosphocholine and ceramide in a divalent metal ion-dependent manner. Bc-SMase is a homologue of mammalian neutral SMase (nSMase) and mimics the actions of the endogenous mammalian nSMase in causing differentiation, development, aging, and apoptosis. Thus Bc-SMase may be a good model for the poorly characterized mammalian nSMase. The metal ion activation of sphingomyelinase activity of Bc-SMase was in the order Co2+ &gt; or = Mn2+ &gt; or = Mg2+ &gt;&gt; Ca2+ &gt; or = Sr2+. The first crystal structures of Bc-SMase bound to Co2+, Mg2+, or Ca2+ were determined. The water-bridged double divalent metal ions at the center of the cleft in both the Co2+- and Mg2+-bound forms were concluded to be the catalytic architecture required for sphingomyelinase activity. In contrast, the architecture of Ca2+ binding at the site showed only one binding site. A further single metal-binding site exists at one side edge of the cleft. Based on the highly conserved nature of the residues of the binding sites, the crystal structure of Bc-SMase with bound Mg2+ or Co2+ may provide a common structural framework applicable to phosphohydrolases belonging to the DNase I-like folding superfamily. In addition, the structural features and site-directed mutagenesis suggest that the specific beta-hairpin with the aromatic amino acid residues participates in binding to the membrane-bound sphingomyelin substrate.

2DDR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_cereus Bacillus cereus] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Sphingomyelin_phosphodiesterase Sphingomyelin phosphodiesterase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.4.12 3.1.4.12] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2DDR OCA].  

[[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]]

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