Identification and characterization of d-arabinose reductase and d-arabinose transporters from Pichia stipitis

Although Pichia stipitis CBS 6054 grows using d-arabinose as the sole carbon source, the hypothetical pathway has not yet been clarified at the molecular level. We herein purified NAD(P)H-dependent d-arabinose reductase from cells grown on d-arabinose, and found that the enzyme was identical to the known d-xylose reductase (XR).

The enzyme activity of XR with d-arabinose was previously reported to be only 1% that with d-xylose. The k cat / K m value with d-arabinose (1.27 min −1 mM −1 ), which was determined using the recombinant enzyme, was 13.6- and 10.5-fold lower than those with l-arabinose and d-xylose, respectively. Among the 34 putative sugar transporters from P. stipitis , only seven genes exhibited uptake ability not only for d-arabinose, but also for d-glucose and other pentose sugars including d-xylose and l-arabinose in Saccharomyces cerevisiae . d-Xylose reductase, encoded by XYL1 gene, plays as an aldose reductase involved not only in d-xylose and l-arabinose but also d-arabinose metabolism.