Author(s): Hasper AA, Visser J, de Graaff LH
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Abstract Screening of an Aspergillus niger differential cDNA library, constructed by subtracting cDNA fragments of a xlnR loss-of-function mutant from wild-type cDNA fragments, resulted in the cloning of the gene encoding D-xylose reductase (xyrA). Northern blot analysis using an A. niger wild-type strain, a xlnR multiple-copy strain and a xlnR loss-of-function mutant confirmed that the xyrA gene is regulated by XlnR, the transcriptional activator of the xylanolytic enzyme system in A. niger. D-xylose reductase catalyses the NADPH-dependent reduction of D-xylose to xylitol, which is the first step in D-xylose catabolism in fungi. Until now, XlnR was shown to control the transcription of genes encoding extracellular hydrolytic enzymes involved in cellulose and xylan degradation. In the present study, we show that A. niger is able to harmonize its sugar metabolism and extracellular xylan degradation via XlnR by regulating the expression of XyrA.
This article was published in Mol Microbiol
and referenced in Fungal Genomics & Biology