title: The Hypocrea jecorina (syn. Trichoderma reesei) lxr1 gene encodes a D-mannitol dehydrogenase and is not involved in L-arabinose catabolism.
abstract: The Hypocrea jecorina LXR1 was described as the first fungal L-xylulose reductase responsible for NADPH dependent reduction of L-xylulose to xylitol in L-arabinose catabolism. Phylogenetic analysis now reveals that LXR1 forms a clade with fungal D-mannitol 2-dehydrogenases. Lxr1 and the orthologous Aspergillus niger mtdA are not induced by L-arabinose but expressed at low levels during growth on different carbon sources. Deletion of lxr1 does not affect growth on L-arabinose and L-xylulose reductase activity remains unaltered whereas D-mannitol 2-dehydrogenase activities are reduced. We conclude that LXR1 is a D-mannitol 2-dehydrogenase and that a true LXR1 is still awaiting discovery.
authors.affiliation: Research Area Gene Technology and Applied Biochemistry, Institute of Chemical Engineering, TU Vienna, Getreidemarkt 9, A-1060 Wien, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Metz
authors.forename: Ronald P
authors.initials: RP
authors.lastname: de Vries
authors.forename: Stefan
authors.initials: S
authors.lastname: Polak
authors.forename: Verena
authors.initials: V
authors.lastname: Seidl
authors.forename: Bernhard
authors.initials: B
authors.lastname: Seiboth
mesh_terms: D001089:Arabinose / Q000378:metabolism*; D005800:Genes, Fungal; D008354:Mannitol Dehydrogenases / Q000235:genetics* / Q000378:metabolism; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics*
chemical_list: D001089:Arabinose; D008354:Mannitol Dehydrogenases