2xom

Publication Abstract from PubMed

The microbial enzymes that depolymerize plant cell wall polysaccharides, ultimately promoting energy liberation and carbon recycling, are typically complex in their modularity and often contain carbohydrate-binding modules (CBMs). Here, through analysis of an unknown module from a Thermotoga maritima endo-beta-1,4-galactanase, we identify a new family of CBMs that are most frequently found appended to proteins with beta-1,4-galactanase activity. Polysaccharide microarray screening, immunofluorescence microscopy, and biochemical analysis of the isolated module demonstrate the specificity of the module, here called TmCBM61, for beta-1,4-linked galactose-containing ligands, making it the founding member of family CBM61. The ultra-high resolution X-ray crystal structures of TmCBM61 (0.95 and 1.4 A resolution) in complex with beta-1,4-galactotriose reveal the molecular basis of the specificity of the CBM for beta-1,4-galactan. Analysis of these structures provides insight into the recognition of an unexpected helical galactan conformation through a mode of binding that resembles the recognition of starch.

Recognition of the helical structure of beta-1,4-galactan by a new family of carbohydrate-binding modules.,Cid M, Pedersen HL, Kaneko S, Coutinho PM, Henrissat B, Willats WG, Boraston AB J Biol Chem. 2010 Nov 12;285(46):35999-6009. Epub 2010 Sep 8. PMID:20826814^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.