Structural highlights
FunctionG8XR50_LEUME Production of extracellular glucans, that are thought to play a key role in the development of the dental plaque because of their ability to adhere to smooth surfaces and mediate the aggregation of bacterial cells and food debris.[ARBA:ARBA00003243] Publication Abstract from PubMedThe alpha-(1-->2) branching sucrase DeltaN123-GBD-CD2 is an enzyme belonging to the Glycoside-Hydrolase family 70 (GH70) that catalyses the transfer of D-glucosyl units from sucrose to dextrans or glucooligosaccharides via the formation of alpha-(1-->2) glucosidic linkages. The first structures of DeltaN123-GBD-CD2 in complex with D-glucose, isomaltosyl or isomaltotriosyl residues were solved. The glucose complex revealed three glucose binding sites in the catalytic gorge and six additional ones at the surface of domains B, IV and V. Soaking with isomaltotriose or glucooligosaccharides led to structures in which isomaltosyl or isomaltriosyl residues were found in glucan binding pockets belonging to domain V. One aromatic residue is systematically identified at the bottom of these pockets in stacking interaction with one glucosyl moiety. The carbohydrate is also maintained by a network of hydrogen bonds and van der Waals interactions. The sequence of these binding pockets is conserved and repeatedly present in the domain V of GH70 glucansucrases known to bind alpha-glucans. These findings provide the first structural evidence of the molecular interaction occurring between isomaltooligosaccharides and the domain V of the GH70 enzymes. Structural insights into the carbohydrate-binding ability of an alpha-(1-->2) branching sucrase from glycoside-hydrolase family 70.,Brison Y, Malbert Y, Czaplicki G, Mourey L, Remaud-Simeon M, Tranier S J Biol Chem. 2016 Feb 10. pii: jbc.M115.688796. PMID:26865636[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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