2c0h | pdb_00002c0h
X-RAY STRUCTURE OF BETA-MANNANASE FROM BLUE MUSSEL MYTILUS EDULIS
Structural highlights
Function[MANA_MYTED] Hydrolyzes 1,4-beta linked polysaccharide backbones of mannans. Hydrolyzes mannohexaose (M6) preferentially to mannotriose (M4) and less preferentially to mannotetraose (M3), mannopentaose (M5), and mannobiose (M2); hydrolyzes M5 preferentially to M2, and M3, and less preferentially to mannotetraose M4; hydrolyzes M4 preferentially to M3, and less preferentially to mannose (M1), plus very little M2. Does not hydrolyze mannobiose or mannotriose. Does not hydrolyze xlyan, starch, cellulose or galactose.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedEndo-beta-1,4-d-mannanase is the key depolymerizing enzyme for beta-1,4-mannan polymers present in the cell walls of plants and some algae, as well as in some types of plant seeds. Endo-1,4-beta-mannanase from blue mussel Mytilus edulis (MeMan5A) belongs to the glycoside hydrolase (GH) family 5 enzymes. The MeMan5A structure has been determined to 1.6A resolution using the multiple-wavelength anomalous dispersion method at the selenium K edge with selenomethionyl MeMan5A expressed in the yeast Pichia pastoris. As expected for GH 5 enzymes, the structure showed a (betaalpha)(8)-barrel fold. An unusually large number of histidine side-chains are exposed on the surface, which may relate to its location within the crystalline style of the digestive tract of the mussel. Kinetic analysis of MeMan5A revealed that the enzyme requires at least six subsites for efficient hydrolysis. Mannotetraose (M4) and mannopentaose (M5) were shown to interact with subsites -3 to +1, and -3 to +2, respectively. A clear kinetic threshold was observed when going from M4 to M5, indicating that the +2 subsite provides important interaction in the hydrolysis of short oligomeric mannose substrates. The catalytic centre motif at subsite -1 found in superfamily GH clan A is, as expected, conserved in MeMan5A, but the architecture of the catalytic cleft differs significantly from other GH 5 enzyme structures. We therefore suggest that MeMan5A represents a new subfamily in GH 5. Three-dimensional crystal structure and enzymic characterization of beta-mannanase Man5A from blue mussel Mytilus edulis.,Larsson AM, Anderson L, Xu B, Munoz IG, Uson I, Janson JC, Stalbrand H, Stahlberg J J Mol Biol. 2006 Apr 14;357(5):1500-10. Epub 2006 Jan 31. PMID:16487541[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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