title: Modification of linear (β1→3)-linked gluco-oligosaccharides with a novel recombinant β-glucosyltransferase (trans-β-glucosidase) enzyme from Bradyrhizobium diazoefficiens.
abstract: Recently, we have shown that glycoside hydrolases enzymes of family GH17 from proteobacteria (genera Pseudomonas, Azotobacter) catalyze elongation transfer reactions with laminari-oligosaccharides generating (β1→3) linkages preferably and to a lesser extent (β1→6) or (β1→4) linkages. In the present study, the cloning and characterization of the gene encoding the structurally very similar GH17 domain of the NdvB enzyme from Bradyrhizobium diazoefficiens, designated Glt20, as well as its catalytic properties are described. The Glt20 enzyme was strikingly different from the previously investigated bacterial GH17 enzymes, both regarding substrate specificity and product formation. The Azotobacter and Pseudomonas enzymes cleaved the donor laminari-oligosaccharide substrates three or four moieties from the non-reducing end, generating linear oligosaccharides. In contrast, the Glt20 enzyme cleaved donor laminari-oligosaccharide substrates two glucose moieties from the reducing end, releasing laminaribiose and transferring the remainder to laminari-oligosaccharide acceptor substrates creating only (β1→3)(β1→6) branching points. This enables Glt20 to transfer larger oligosaccharide chains than the other type of bacterial enzymes previously described, and helps explain the biologically significant formation of cyclic β-glucans in B. diazoefficiens.
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
authors.forename: Justyna M
authors.initials: JM
authors.lastname: Dobruchowska
authors.affiliation: Matís, Vínlandsleid 12, 113 Reykjavík, Iceland.
authors.forename: Jon O
authors.initials: JO
authors.lastname: Jonsson
authors.affiliation: Matís, Vínlandsleid 12, 113 Reykjavík, Iceland.
authors.forename: Olafur H
authors.initials: OH
authors.lastname: Fridjonsson
authors.affiliation: Prokazyme ehf. Vínlandsleid 10, 113 Reykjavík, Iceland.
authors.forename: Arnthor
authors.initials: A
authors.lastname: Aevarsson
authors.affiliation: Prokazyme ehf. Vínlandsleid 10, 113 Reykjavík, Iceland.
authors.forename: Jakob K
authors.initials: JK
authors.lastname: Kristjansson
authors.affiliation: Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Altenbuchner
authors.affiliation: Institut für Industrielle Genetik, Universität Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: Hildegard
authors.initials: H
authors.lastname: Watzlawick
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.|NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Gerwig
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.affiliation: Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.|NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Johannis P
authors.initials: JP
authors.lastname: Kamerling
authors.affiliation: Matís, Vínlandsleid 12, 113 Reykjavík, Iceland gudmundur.o.hreggvidsson@matis.is.|Department of Biology, University of Iceland, Sturlugata 7, 101 Reykjavík, Iceland.
authors.forename: Gudmundur O
authors.initials: GO
authors.lastname: Hreggvidsson
mesh_terms: D055162:Biocatalysis; D020369:Bradyrhizobium / Q000201:enzymology*; D009844:Oligosaccharides / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D011994:Recombinant Proteins; D001617:beta-Glucosidase
keywords: Bradyrhizobium diazoefficiens; non-Leloir β-glucosyltransferase; oligosaccharide synthesis; structural analysis; β-d-glucans