1gym

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spinqualitylabelsall models 1gym, resolution 2.2Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

PHOSPHATIDYLINOSITOL-SPECIFIC PHOSPHOLIPASE C IN COMPLEX WITH GLUCOSAMINE-(ALPHA-1-6)-MYO-INOSITOL

Overview

Numerous proteins on the external surface of the plasma membrane are, anchored by glycosylated derivatives of phosphatidylinositol (GPI), rather, than by hydrophobic amino acids embedded in the phospholipid bilayer., These GPI anchors are cleaved by phosphatidylinositol-specific, phospholipases C (PI-PLCs) to release a water-soluble protein with an, exposed glycosylinositol moiety and diacylglycerol, which remains in the, membrane. We have previously determined the crystal structure of Bacillus, cereus PI-PLC, the enzyme which is widely used to release GPI-anchored, proteins from membranes, as free enzyme and also in complex with, myo-inositol [Heinz, D.W., Ryan, M. Bullock, T.L., & Griffith, O. H., (1995) EMBO J. 14, 3855-3863]. Here we report the refined 2.2 A crystal, structure of this enzyme complexed with a segment of the core of all GPI, anchors, glucosaminyl(alpha 1-->6)-D-myo-inositol [GlcN-(alpha 1-->6)Ins, ]. The myo-inositol moiety of GlcN(alpha 1-->6)Ins is well-defined and, occupies essentially the same position in the active site as does free, myo-inositol, which provides convincing evidence that the enzyme utilizes, the same catalytic mechanism for cleavage of PI and GPI anchors. The, myo-inositol moiety makes several specific hydrogen bonding interactions, with active site residues. In contrast, the glucosamine moiety lies, exposed to solvent at the entrance of the active site with minimal, specific protein contacts. The glucosamine moiety is also less, well-defined, suggesting enhanced conformational flexibility. On the basis, of the positioning of GlcN(alpha 1-->6)Ins in the active site, it is, predicted that the remainder of the GPI-glycan makes little or no specific, interactions with B. cereus PI-PLC. This explains why B. cereus PI-PLC can, cleave GPI anchors having variable glycan structures.

About this Structure

1GYM is a Single protein structure of sequence from Bacillus cereus with MYG as ligand. Active as Phosphatidylinositol diacylglycerol-lyase, with EC number 4.6.1.13 Full crystallographic information is available from OCA.

Reference

Crystal structure of phosphatidylinositol-specific phospholipase C from Bacillus cereus in complex with glucosaminyl(alpha 1-->6)-D-myo-inositol, an essential fragment of GPI anchors., Heinz DW, Ryan M, Smith MP, Weaver LH, Keana JF, Griffith OH, Biochemistry. 1996 Jul 23;35(29):9496-504. PMID:8755729

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