Kinetics and Predicted Structure of a Novel Xylose Reductase from Chaetomium thermophilum

• Main Authors: Julian Quehenberger, Tom Reichenbach, Niklas Baumann, Lukas Rettenbacher, Christina Divne, Oliver Spadiut
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: International Journal of Molecular Sciences
• Subjects: xylose reductase; Chaetomium thermophilum; kinetics; structure; homology model; cofactor binding; stability
• Online Access: http://www.mdpi.com/1422-0067/20/1/185

While in search of an enzyme for the conversion of xylose to xylitol at elevated temperatures, a xylose reductase (XR) gene was identified in the genome of the thermophilic fungus Chaetomium thermophilum. The gene was heterologously expressed in Escherichia coli as a His6-tagged fusion protein and characterized for function and structure. The enzyme exhibits dual cofactor specificity for NADPH and NADH and prefers D-xylose over other pentoses and investigated hexoses. A homology model based on a XR from Candida tenuis was generated and the architecture of the cofactor binding site was investigated in detail. Despite the outstanding thermophilicity of its host the enzyme is, however, not thermostable.