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Updated: Jul 10, 2026
Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Heterologous expression and biochemical characterization of soluble human xylosyltransferase II
Javier Carrera Casanova1, Joachim Kuhn, Knut Kleesiek
1Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany.
Abstract:
Human xylosyltransferase II (EC 2.4.2.26, XT-II) represents an isoform of xylosyltransferase I (XT-I). Recently, we and others provided first evidence that XT-II is capable of initiating the biosynthesis of glycosaminoglycan chains in proteoglycans. Here, a soluble form of human XT-II was expressed in the yeast Pichia pastoris and the substrate specificity for various acceptors was investigated, pointing to a modified bikunin peptide to be the optimal XT-II acceptor (K(M)=1.9 microM). Furthermore, biochemical characterization of XT-II showed that this enzyme was strongly inhibited by nucleotides and glycosaminoglycans. Its temperature optimum, stability, and ion dependency were further examined, demonstrating necessity for Mg(2+) or Mn(2+) ions for its enzymatic activity. Our data show for the first time that XT-I and XT-II are xylosyltransferases with similar but not identical properties, pointing to their potential role in modulating the cellular proteoglycan pool.
