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

17 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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