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United States Department of Agriculture

Agricultural Research Service

Title: Cloning, Sequencing and Analysis of An Aldose (Xylose) Reductase Gene from the Xylose-Fermenting Yeast Pachysolen Tannophilus

item Shepherd, Hurley

Submitted to: Yeast
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 6, 1996
Publication Date: N/A

Interpretive Summary: Xylose is an abundant sugar found in plants which can be recovered easily. Conversion of xylose to ethanol would enhance the value of agricultural residues, but an efficient method has not been developed. An enzymatic pathway for the conversion has been identified in a yeast, Pachysolen tannophilus. A key enzyme in this pathway has been cloned and the DNA sequence analyzed. Control elements have been located and characterized. This work should lead to an understanding of how to increase expression of this gene or other fungal genes involved in the production of economically useful products.

Technical Abstract: A xylose reductase gene was isolated from the xylose-fermenting yeast Pachysolen tannophilus as a cDNA clone by selecting clones that hybridized specifically to xylose-inducible messenger RNA. Use of the cDNA clone as a probe in Northern hybridizations identified a single xylose-inducible message large enough to encode a 36 kD protein. A corresponding genomic clone was isolated as a 3 kbp EcoR1 fragment that specifically hybridized to the cDNA clone. The sequence of the cDNA and the largest open reading frame of the genomic clone are identical. The predicted translation product is 317 amino acid residues with a calculated mass of 36.2 kD, equivalent to that reported for purified P. tannophilus xylose reductase. There is also considerable sequence similarity to, and features of, a superfamily of oxidoreductases. The pattern of expression of the mRNA corresponds to the pattern of expression of xylose reductase activity in cultures grown in various sugars.

Last Modified: 4/22/2015
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