title: Arbutin synthase, a novel member of the NRD1beta glycosyltransferase family, is a unique multifunctional enzyme converting various natural products and xenobiotics.
abstract: Plant glucosyltransferases (GTs) play a crucial role in natural product biosynthesis and metabolization of xenobiotics. We expressed the arbutin synthase (AS) cDNA from Rauvolfia serpentina cell suspension cultures in Escherichia coli with a 6 x His tag and purified the active enzyme to homogeneity. The recombinant enzyme had a temperature optimum of 50 degrees C and showed two different pH optima (4.5 and 6.8 or 7.5, depending on the buffer). Out of 74 natural and synthetic phenols and two cinnamyl alcohols tested as substrates for the AS, 45 were accepted, covering a broad range of structural features. Converting rates comparable to hydroquinone were not achieved. In contrast to this broad acceptor substrate specificity, only pyrimidine nucleotide activated glucose was tolerated as a donor substrate. Nucleotide and amino acid sequence analysis revealed AS to be a new member of the NRD1beta family of glycosyl transferases and placed the enzyme into the group of plant secondary product GTs. Arbutin synthase is therefore the first example of a broad spectrum multifunctional glucosyltransferase.
authors.affiliation: Johannes Gutenberg-University Mainz, Institute of Pharmacy, Department of Pharmaceutical Biology, Staudinger Weg 5, D-55099, Mainz, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Hefner
authors.forename: Joachim
authors.initials: J
authors.lastname: Arend
authors.forename: Heribert
authors.initials: H
authors.lastname: Warzecha
authors.forename: Karsten
authors.initials: K
authors.lastname: Siems
authors.forename: Joachim
authors.initials: J
authors.lastname: Stöckigt
mesh_terms: D000595:Amino Acid Sequence; D001104:Arbutin / Q000096:biosynthesis*; D001483:Base Sequence; D001688:Biological Products / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D016695:Glycosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011926:Rauwolfia / Q000201:enzymology / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D001688:Biological Products; D018076:DNA, Complementary; D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D015262:Xenobiotics; D001104:Arbutin; D016695:Glycosyltransferases