2cdo
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STRUCTURE OF AGARASE CARBOHYDRATE BINDING MODULE IN COMPLEX WITH NEOAGAROHEXAOSE
OverviewOverview
Carbohydrate recognition is central to the biological and industrial, exploitation of plant structural polysaccharides. These insoluble polymers, are recalcitrant to microbial degradation, and enzymes that catalyze this, process generally contain non-catalytic carbohydrate binding modules, (CBMs) that potentiate activity by increasing substrate binding. Agarose, a repeat of the disaccharide, 3,6-anhydro-alpha-L-galactose-(1,3)-beta-D-galactopyranose-(1,4), is the, dominant matrix polysaccharide in marine algae, yet the role of CBMs in, the hydrolysis of this important polymer has not previously been explored., Here we show that family 6 CBMs, present in two different beta-agarases, bind specifically to the non-reducing end of agarose chains, recognizing, only the first repeat of the disaccharide. The crystal structure of one of, these modules Aga16B-CBM6-2, in complex with neoagarohexaose, reveals the, mechanism by which the protein displays exquisite specificity, targeting, the equatorial O4 and the axial O3 of the anhydro-L-galactose. Targeting, of the CBM6 to the non-reducing end of agarose chains may direct the, appended catalytic modules to areas of the plant cell wall attacked by, beta-agarases where the matrix polysaccharide is likely to be more, amenable to further enzymic hydrolysis.
About this StructureAbout this Structure
2CDO is a Single protein structure of sequence from Saccharophagus degradans with , and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Family 6 carbohydrate binding modules in beta-agarases display exquisite selectivity for the non-reducing termini of agarose chains., Henshaw J, Horne-Bitschy A, van Bueren AL, Money VA, Bolam DN, Czjzek M, Ekborg NA, Weiner RM, Hutcheson SW, Davies GJ, Boraston AB, Gilbert HJ, J Biol Chem. 2006 Jun 23;281(25):17099-107. Epub 2006 Apr 6. PMID:16601125
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