This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Degradation/Utilization/Assimilation → Carbohydrates Degradation → Sugars Degradation → Xylose Degradation|
Expected Taxonomic Range: Fungi
The pentose α-D-xylopyranose (D-xylose, wood sugar) is a major monosaccharide component of xylan, a polysaccharide found in plant cell walls. Fungi degrade xylan via an extracellularly secreted xylanolytic enzyme system. Two endoxylanases cleave the xylan main chain, which is composed of β-1,4-linked D-xylose residues, to xylo-oligosaccharides and D-xylose. The oligosaccharides are further cleaved by β-xylosidase to D-xylose (in [Hasper00]). α-D-xylopyranose is further catabolized to D-xylulose 5-phosphate which enters the non-oxidative pentose phosphate pathway, as shown here and in the pathway link [Hasper00, deGroot05].
About This Pathway
The initial step in this pathway involves reduction of α-D-xylopyranose to produce xylitol which is degraded as shown in the pathway link. In Trichoderma reesei , the first step appears to be mainly catalyzed by aldose reductase encoded by gene xyl1 which also catalyzes the first step in L-arabinose catabolism in this organism (see pathway L-arabinose degradation II). In addition, this aldose reductase catalyzes the first step in D-galactose degradation in some fungi (see pathway galactose degradation IV). Reviewed in [Seiboth11].
Superpathways: superpathway of pentose and pentitol degradation
Hasper00: Hasper AA, Visser J, de Graaff LH (2000). "The Aspergillus niger transcriptional activator XlnR, which is involved in the degradation of the polysaccharides xylan and cellulose, also regulates D-xylose reductase gene expression." Mol Microbiol 36(1);193-200. PMID: 10760176
Akel09: Akel E, Metz B, Seiboth B, Kubicek CP (2009). "Molecular regulation of arabinan and L-arabinose metabolism in Hypocrea jecorina (Trichoderma reesei)." Eukaryot Cell 8(12);1837-44. PMID: 19801419
Chen09a: Chen LC, Huang SC, Chuankhayan P, Chen CD, Huang YC, Jeyakanthan J, Pang HF, Men LC, Chen YC, Wang YK, Liu MY, Wu TK, Chen CJ (2009). "Purification, crystallization and preliminary X-ray crystallographic analysis of xylose reductase from Candida tropicalis." Acta Crystallogr Sect F Struct Biol Cryst Commun 65(Pt 4);419-21. PMID: 19342796
Fernandes09: Fernandes S, Tuohy MG, Murray PG (2009). "Xylose reductase from the thermophilic fungus Talaromyces emersonii: cloning and heterologous expression of the native gene (Texr) and a double mutant (TexrK271R + N273D) with altered coenzyme specificity." J Biosci 34(6);881-90. PMID: 20093741
Lee03d: Lee JK, Koo BS, Kim SY (2003). "Cloning and characterization of the xyl1 gene, encoding an NADH-preferring xylose reductase from Candida parapsilosis, and its functional expression in Candida tropicalis." Appl Environ Microbiol 69(10);6179-88. PMID: 14532079
Neuhauser97: Neuhauser W, Haltrich D, Kulbe KD, Nidetzky B (1997). "NAD(P)H-dependent aldose reductase from the xylose-assimilating yeast Candida tenuis. Isolation, characterization and biochemical properties of the enzyme." Biochem J 326 ( Pt 3);683-92. PMID: 9307017
Nidetzky03: Nidetzky B, Bruggler K, Kratzer R, Mayr P (2003). "Multiple forms of xylose reductase in Candida intermedia: comparison of their functional properties using quantitative structure-activity relationships, steady-state kinetic analysis, and pH studies." J Agric Food Chem 51(27);7930-5. PMID: 14690376
Rao06a: Rao RS, Jyothi ChP, Prakasham RS, Sarma PN, Rao LV (2006). "Xylitol production from corn fiber and sugarcane bagasse hydrolysates by Candida tropicalis." Bioresour Technol 97(15);1974-8. PMID: 16242318
Seiboth07: Seiboth B, Gamauf C, Pail M, Hartl L, Kubicek CP (2007). "The D-xylose reductase of Hypocrea jecorina is the major aldose reductase in pentose and D-galactose catabolism and necessary for beta-galactosidase and cellulase induction by lactose." Mol Microbiol 66(4);890-900. PMID: 17924946
Verduyn85: Verduyn C, Van Kleef R, Frank J, Schreuder H, Van Dijken JP, Scheffers WA (1985). "Properties of the NAD(P)H-dependent xylose reductase from the xylose-fermenting yeast Pichia stipitis." Biochem J 226(3);669-77. PMID: 3921014
Woodyer05: Woodyer R, Simurdiak M, van der Donk WA, Zhao H (2005). "Heterologous expression, purification, and characterization of a highly active xylose reductase from Neurospora crassa." Appl Environ Microbiol 71(3);1642-7. PMID: 15746370
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