Structural highlights
Publication Abstract from PubMedThe reuteransucrase GTFA from Lactobacillus reuteri 121, which belongs to glycosyl hydrolase family GH70, synthesizes branched alpha-glucans with both alpha-1,6- and alpha-1,4-glycosidic linkages (reuteran) from sucrose. The crystal structure of GTFA-DeltaN, a 118 kDa fragment of GTFA comprising residues 745-1763 and including the catalytic domain, was determined at 3.6 A resolution by molecular replacement. The crystals have large solvent channels and an unusually high solvent content of 85%. GTFA-DeltaN has the same domain arrangement and domain topologies as observed in previously determined GH70 glucansucrase structures. The architecture of the GTFA-DeltaN active site and binding pocket confirms that glucansucrases have a conserved substrate specificity for sucrose. However, this first crystal structure of an alpha-1,6/alpha-1,4-specific glucansucrase shows that residues from conserved sequence motif IV (1128-1136 in GTFA-DeltaN) contribute to the acceptor-binding subsites and that they display differences compared with other structurally characterized glucansucrases. In particular, the structure clarifies the importance of residues following the transition-state stabilizer for product specificity, and especially residue Asn1134, which is in a position to interact with sugar units in acceptor subsite +2. Structure of the alpha-1,6/alpha-1,4-specific glucansucrase GTFA from Lactobacillus reuteri 121.,Pijning T, Vujicic-Zagar A, Kralj S, Dijkhuizen L, Dijkstra BW Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Dec 1;68(Pt 12):1448-54., doi: 10.1107/S1744309112044168. Epub 2012 Nov 14. PMID:23192022[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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