title: Sorbitol dehydrogenase of Aspergillus niger, SdhA, is part of the oxido-reductive D-galactose pathway and essential for D-sorbitol catabolism.
abstract: In filamentous fungi D-galactose can be catabolised through the oxido-reductive and/or the Leloir pathway. In the oxido-reductive pathway D-galactose is converted to d-fructose in a series of steps where the last step is the oxidation of d-sorbitol by an NAD-dependent dehydrogenase. We identified a sorbitol dehydrogenase gene, sdhA (JGI53356), in Aspergillus niger encoding a medium chain dehydrogenase which is involved in D-galactose and D-sorbitol catabolism. The gene is upregulated in the presence of D-galactose, galactitol and D-sorbitol. An sdhA deletion strain showed reduced growth on galactitol and growth on D-sorbitol was completely abolished. The purified enzyme converted D-sorbitol to D-fructose with K(m) of 50±5 mM and v(max) of 80±10 U/mg.
authors.affiliation: VTT Technical Research Centre of Finland, Finland.
authors.forename: Outi M
authors.initials: OM
authors.lastname: Koivistoinen
authors.forename: Peter
authors.initials: P
authors.lastname: Richard
authors.forename: Merja
authors.initials: M
authors.lastname: Penttilä
authors.forename: Laura
authors.initials: L
authors.lastname: Ruohonen
authors.forename: Dominik
authors.initials: D
authors.lastname: Mojzita
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D001483:Base Sequence; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D007700:Kinetics; D007064:L-Iditol 2-Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013012:Sorbitol / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D011994:Recombinant Proteins; D013012:Sorbitol; D007064:L-Iditol 2-Dehydrogenase; D005690:Galactose