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Functional Identification of Arabidopsis ATSIP2 (At3g57520) as an Alkaline α-Galactosidase with a Substrate Specificity for Raffinose and an Apparent Sink-Specific Expression Pattern

Peters, Shaun ; Egert, Aurélie ; Stieger, Bruno ; Keller, Felix

In: Plant and Cell Physiology, 2010, vol. 51, no. 10, p. 1815-1819

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    Titre
    • Functional Identification of Arabidopsis ATSIP2 (At3g57520) as an Alkaline α-Galactosidase with a Substrate Specificity for Raffinose and an Apparent Sink-Specific Expression Pattern
    Auteur
    • Peters, Shaun. Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
    • Egert, Aurélie. Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
    • Stieger, Bruno. Division of Clinical Pharmacology and Toxicology, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland
    • Keller, Felix. Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Plant and Cell Physiology, 2010, vol. 51, no. 10, p. 1815-1819. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:299256
    Summary
    Arabidopsis ATSIP2 has recently been suggested to be a raffinose synthase gene. However, it has high amino acid identity to functionally characterized alkaline α-galactosidases from Cucumis melo and Zea mays. Using the Sf9 insect cell expression system, we demonstrate that recombinant ATSIP2 is a genuine alkaline α-galactosidase with a distinct substrate specificity for raffinose, and not a raffinose synthase. A β-glucuronidase reporter construct using the ATSIP2 promoter shows that ATSIP2 is strongly expressed in sink tissues of Arabidopsis, i.e. sink leaves and non-xylem parts of the root stele, suggesting a physiological function in raffinose phloem unloading