title: A CGTase with high coupling activity using γ-cyclodextrin isolated from a novel strain clustering under the genus Carboxydocella.
abstract: Cyclodextrin glucanotransferases (CGTases; EC 2.4.1.19) have mainly been characterized for their ability to produce cyclodextrins (CDs) from starch in an intramolecular transglycosylation reaction (cyclization). However, this class of enzymes can also catalyze intermolecular transglycosylation via disproportionation or coupling reactions onto a wide array of acceptors and could therefore be valuable as a tool for glycosylation.In this paper, we report the gene isolation, via the CODEHOP strategy, expression and characterization of a novel CGTase (CspCGT13) from a Carboxydocella sp. This enzyme is the first glycoside hydrolase isolated from the genus, indicating starch degradation via cyclodextrin production in the Carboxydocella strain. The fundamental reactivities of this novel CGTase are characterized and compared with two commercial CGTases, assayed under identical condition, in order to facilitate interpretation of the results. The comparison showed that the enzyme, CspCGT13, displayed high coupling activity using γ-CD as donor, despite preferentially forming α- and β-CD in the cyclization reaction using wheat starch as substrate. Comparison of subsite conservation within previously characterized CGTases showed significant sequence variation in subsites -3 and -7, which may be important for the coupling activity.
authors.affiliation: Department of Chemistry, Biotechnology, PO Box 124, Lund SE-221 00, Sweden zubaida.gulshan_kazi@biotek.lu.se.
authors.forename: Kazi Z G
authors.initials: KZ
authors.lastname: Ara
authors.affiliation: Department of Chemistry, Biotechnology, PO Box 124, Lund SE-221 00, Sweden.
authors.forename: Pontus
authors.initials: P
authors.lastname: Lundemo
authors.affiliation: Matís, Vínlandsleið 12, Reykjavík 113, Iceland.
authors.forename: Olafur H
authors.initials: OH
authors.lastname: Fridjonsson
authors.affiliation: Matís, Vínlandsleið 12, Reykjavík 113, Iceland Faculty of Life and Environmental Sciences, University of Iceland, Askja, Reykjavik IS-101, Iceland.
authors.forename: Gudmundur O
authors.initials: GO
authors.lastname: Hreggvidsson
authors.affiliation: Department of Chemistry, Biotechnology, PO Box 124, Lund SE-221 00, Sweden.
authors.forename: Patrick
authors.initials: P
authors.lastname: Adlercreutz
authors.affiliation: Department of Chemistry, Biotechnology, PO Box 124, Lund SE-221 00, Sweden.
authors.forename: Eva Nordberg
authors.initials: EN
authors.lastname: Karlsson
mesh_terms: D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D047408:gamma-Cyclodextrins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D047408:gamma-Cyclodextrins; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase
keywords: CODEHOP; coupling; cyclodextrin glucanotransferase; γ-cyclodextrin