L-xylo-3-hexulose reductase is the missing link in the oxidoreductive pathway for D-galactose catabolism in filamentous fungi

Dominik Mojzita, S. Herold, B. Metz, B. Seiboth, Peter Richard (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    18 Citations (Scopus)

    Abstract

    In addition to the well established Leloir pathway for the catabolism of D-galactose in fungi, the oxidoreductive pathway has been recently identified. In this oxidoreductive pathway, D-galactose is converted via a series of NADPH-dependent reductions and NAD+-dependent oxidations into D-fructose. The pathway intermediates include galactitol, L-xylo-3-hexulose, and D-sorbitol. This study identified the missing link in the pathway, the L-xylo-3-hexulose reductase that catalyzes the conversion of L-xylo-3-hexulose to D-sorbitol. In Trichoderma reesei (Hypocrea jecorina) and Aspergillus niger, we identified the genes lxr4 and xhrA, respectively, that encode the L-xylo-3-hexulose reductases. The deletion of these genes resulted in no growth on galactitol and in reduced growth on D-galactose. The LXR4 was heterologously expressed, and the purified protein showed high specificity for L-xylo-3-hexulose with a Km = 2.0 ± 0.5 mM and a Vmax = 5.5 ± 1.0 units/mg. We also confirmed that the product of the LXR4 reaction is D-sorbitol.
    Original languageEnglish
    Pages (from-to)26010-26018
    Number of pages8
    JournalJournal of Biological Chemistry
    Volume287
    Issue number31
    DOIs
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

    Keywords

    • Aspergillus niger
    • Trichoderma reesei
    • Hypocrea jecorina
    • D-galactose metabolism
    • D-galactose
    • L-xylo-3-hexulose
    • L-xylo-3-hexulose reductase
    • xhrA
    • lxr4

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