2c0h
|
X-RAY STRUCTURE OF BETA-MANNANASE FROM BLUE MUSSEL MYTILUS EDULIS
OverviewOverview
Endo-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.
About this StructureAbout this Structure
2C0H is a Single protein structure of sequence from Mytilus edulis with SO4 as ligand. Active as Mannan endo-1,4-beta-mannosidase, with EC number 3.2.1.78 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
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
Page seeded by OCA on Mon Nov 5 17:54:38 2007