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 → L-arabinose Degradation|
Expected Taxonomic Range: Fungi
Bacteria and fungi generally utilize L-arabinose derived from plant matter via different pathways. The bacterial pathways are shown in L-arabinose degradation I which involves isomerase, kinase and epimerase steps; and in L-arabinose degradation III which involves oxidative, non-phosphorylative steps. The fungal pathway, which involves oxidation and reduction steps followed by a kinase step, is shown here and in the pathway link. The end product of the phosphorylative pathways is D-xylulose 5-phosphate which enters the non-oxidative pentose phosphate pathway as shown in the pathway link ([Richard01a] and in [Verho04, deGroot05] and reviewed in [Seiboth11]).
L-arabinose is present in plants as arabinan, a polysaccharide constituent of plant cell wall heteropolysaccharides. Fungi such as Aspergillus niger initially degrade arabinan to the pentose sugar L-arabinose using an extracellular arabinanolytic enzyme system. They can then catabolize L-arabinose as a carbon source intracellularly (in [deGroot05]). Expression of the extracellular and intracellular enzymes is specifically and coordinately induced by L-arabinose or L-arabitol (reviewed in [Seiboth11]).
About This Pathway
The initial steps in this pathway involve reduction and oxidation reactions that produce xylitol which is degraded as shown in the pathway link. In the fungi Aspergillus niger and Trichoderma reesei, deletion analysis suggested that the first step may be catalyzed by at least two enzymes. In Aspergillus niger it is catalyzed by a reductase encoded by gene larA that has a preferred specificity for L-arabinose. A candidate for the remaining activity in this organism is D-xylose reductase encoded by gene xyrA (not shown). 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 α-D-xylopyranose catabolism (see pathway xylose degradation II). As shown in pathway xylose degradation II, α-D-xylopyranose is also catabolized by fungi to xylitol. The reduction of L-xylulose to xylitol has been shown to be catalyzed by the product of gene lxrA in Aspergillus niger and by the product of gene lxr3 in Trichoderma reesei, with both enzymes being phylogenetically distinct ([Mojzita10a, Metz13] and in [Seiboth11]). Pathway galactose degradation IV shows that some fungi also catabolize the hexose D-galactose to galactitol. Reviewed in [Seiboth11].
Superpathways: superpathway of pentose and pentitol degradation
Metz13: Metz B, Mojzita D, Herold S, Kubicek CP, Richard P, Seiboth B (2013). "A novel L-xylulose reductase essential for L-arabinose catabolism in Trichoderma reesei." Biochemistry 52(14);2453-60. PMID: 23506391
Mojzita10a: Mojzita D, Vuoristo K, Koivistoinen OM, Penttila M, Richard P (2010). "The 'true' L-xylulose reductase of filamentous fungi identified in Aspergillus niger." FEBS Lett 584(16);3540-4. PMID: 20654618
Verho04: Verho R, Putkonen M, Londesborough J, Penttila M, Richard P (2004). "A novel NADH-linked l-xylulose reductase in the l-arabinose catabolic pathway of yeast." J Biol Chem 279(15);14746-51. PMID: 14736891
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
Ishikura01: Ishikura S, Isaji T, Usami N, Kitahara K, Nakagawa J, Hara A (2001). "Molecular cloning, expression and tissue distribution of hamster diacetyl reductase. Identity with L-xylulose reductase." Chem Biol Interact 130-132(1-3);879-89. PMID: 11306103
Martinez08: Martinez D, Berka RM, Henrissat B, Saloheimo M, Arvas M, Baker SE, Chapman J, Chertkov O, Coutinho PM, Cullen D, Danchin EG, Grigoriev IV, Harris P, Jackson M, Kubicek CP, Han CS, Ho I, Larrondo LF, de Leon AL, Magnuson JK, Merino S, Misra M, Nelson B, Putnam N, Robbertse B, Salamov AA, Schmoll M, Terry A, Thayer N, Westerholm-Parvinen A, Schoch CL, Yao J, Barabote R, Barbote R, Nelson MA, Detter C, Bruce D, Kuske CR, Xie G, Richardson P, Rokhsar DS, Lucas SM, Rubin EM, Dunn-Coleman N, Ward M, Brettin TS (2008). "Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina)." Nat Biotechnol 26(5);553-60. PMID: 18454138
Mojzita10: Mojzita D, Penttila M, Richard P (2010). "Identification of an L-arabinose reductase gene in Aspergillus niger and its role in L-arabinose catabolism." J Biol Chem 285(31);23622-8. PMID: 20511228
Nakagawa02: Nakagawa J, Ishikura S, Asami J, Isaji T, Usami N, Hara A, Sakurai T, Tsuritani K, Oda K, Takahashi M, Yoshimoto M, Otsuka N, Kitamura K (2002). "Molecular characterization of mammalian dicarbonyl/L-xylulose reductase and its localization in kidney." J Biol Chem 277(20);17883-91. PMID: 11882650
Rao06: 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
©2014 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493