A single amino acid change in the L-arabitol dehydrogenase (LadA) from Aspergillus niger broadens its substrate specificity and increases its activity

Blanca Trejo-Aguilar1, Lucy Rutten2, Cecile Ribot3, Manuela Pail1, Han A.B. Wösten1, Ronald P. de Vries1

Author address: 

1Microbiology, Utrecht University, Utrecht, Netherlands, 2Crystal and Structural Chemistry, Utrecht University, Utrecht, Netherlands, 3CNRS-UCB-INSA-Bayer CropScience, Lyon, France


L-arabitol dehydrogenase and xylitol dehydrogenase are part of the fungal pentose catabolic pathway. They are related to sorbitol dehydrogenases from higher eukaryotes. Phylogenetic analysis of L-arabitol dehydrogenases (LAD), xylitol dehydrogenases (XDH) and sorbitol dehydrogenases (SDH) shows that XDHs are more similar to SDHs than LADs. By modeling A. niger LadA and XdhA on the structure of human SDH, we identified two residues in XdhA that were hypothesized to be important for the activity on D-sorbitol. Mutagenesis of one of these residues in LadA resulted in a nearly complete enzyme inactivation for reasons unknown. The other mutation resulted in increased affinity and activity for L-arabitol and sorbitol, demonstrating that this residue is not only important for activity on sorbitol, but also improves the general activity of the enzyme.

abstract No: 


Full conference title: 

    • ECFG 9th (2008)