7jwf

Publication Abstract from PubMed

alpha-Linked galactose is a common carbohydrate motif in nature that is processed by a variety of glycoside hydrolases from different families. Terminal Galalpha1-3Gal motifs are found as a defining feature of different blood group and tissue antigens, as well as the building block of the marine algal galactan lambda-carrageenan. The blood group B antigen and linear alphaGal epitope can be processed by glycoside hydrolases in family GH110, while the presence of genes encoding GH110 enzymes in polysaccharide utilization loci from marine bacteria suggest a role in processing lambda-carrageenan. However, the structure-function relationships underpinning the alpha-1,3-galactosidase activity within family GH110 remain unknown. Here we focus on a GH110 enzyme (PdGH110B) from the carrageenolytic marine bacterium Pseudoalteromonas distincta U2A. We showed the enzyme was active on Galalpha1-3Gal (alphaG2), but not the blood group B antigen. X-Ray crystal structures in complex with galactose and unhydrolyzed alphaG2 revealed the parallel beta-helix fold of the enzyme and the structural basis of its inverting catalytic mechanism. Moreover, an examination of the active site reveals likely adaptations that allow accommodation of fucose in blood group B active GH110 enzymes or, in the case of PdGH110, accommodation of the sulfate groups found on lambda-carrageenan. Overall, this work provides insight into the first member of a predominantly marine clade of GH110 enzymes whilst also illuminating the structural basis of alpha-1,3-galactoside processing by the family as a whole.

The structure of a family 110 glycoside hydrolase provides insight into the hydrolysis of alpha-(1,3)-galactosidic linkages in lambda-carrageenan and blood group antigens.,McGuire BE, Hettle A, Vickers C, King DT, Vocadlo DJ, Boraston AB J Biol Chem. 2020 Oct 30. pii: RA120.015776. doi: 10.1074/jbc.RA120.015776. PMID:33127644^[1]

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