XYL2/YLR070C Summary Help

Standard Name XYL2 1
Systematic Name YLR070C
Feature Type ORF, Verified
Description Xylitol dehydrogenase; converts xylitol to D-xylulose; expression induced by xylose, even though this pentose sugar is not well utilized by S. cerevisiae; null mutant has cell wall defect (1, 2, 3 and see Summary Paragraph)
Chromosomal Location
ChrXII:275211 to 274141 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All XYL2 GO evidence and references
  View Computational GO annotations for XYL2
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
Large-scale survey
32 total interaction(s) for 25 unique genes/features.
Physical Interactions
  • Affinity Capture-RNA: 1
  • Two-hybrid: 1

Genetic Interactions
  • Negative Genetic: 20
  • Phenotypic Enhancement: 2
  • Positive Genetic: 6
  • Synthetic Growth Defect: 2

Expression Summary
Length (a.a.) 356
Molecular Weight (Da) 38,600
Isoelectric Point (pI) 6.08
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXII:275211 to 274141 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1071 275211..274141 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004060

XYL2 encodes xylitol dehydrogenase, a zinc-containing member of the medium-chain dehydrogenase/reductase superfamily (polyol dehdrogenase family; 4, 5). Although XYL2 deletion mutants have cell wall defects (3), and XYL2 expression is induced in the presence of the sugar xylose (1), it is not entirely clear what role Xyl2p plays in S. cerevisiae. Unlike some fungi, such as Pichia stipitis, S. cerevisiae is unable to utilize or ferment xylose, the pentose sugar that is an abundant component of lignocellulose, one of the structural materials common in plants (1, 2). In fungi that do utilize xylose, xylitol dehydrogenase is part of the fungal xylose utilization pathway, a pathway of cytosolic enzymes that convert xylose to xylulose 5-phosphate (6), which is then used by the pentose phosphate pathway (1).

The construction of S. cerevisiae strains able to ferment xylose from woody plant materials is of major industrial interest, because these strains could be used for the efficient production of biofuels (1, 7, 8). The construction of xylitol-producing S. cerevisiae strains is also of industrial interest, primarily because xylitol tastes sweet but its metabolism is independent of insulin, making it safe for diabetics (9).

About the medium-chain dehydrogenase/reductase (MDR) family

Medium-chain dehydrogenase/reductases (MDRs), sometimes referred to as long-chain dehydrogenases (10), constitute an ancient and widespread enzyme superfamily with members found in Bacteria, Archaea, and Eukaryota (4, 5). Many MDR members are basic metabolic enzymes acting on alcohols or aldehydes, and thus these enzymes may have roles in detoxifying alcohols and related compounds, protecting against environmental stresses such as osmotic shock, reduced or elevated temperatures, or oxidative stress (4). The family also includes the mammalian zeta-crystallin lens protein, which may protect the lens against oxidative damage and enzymes which produce lignocellulose in plants (4).

MDR enzymes typically have subunits of about 350 aa residues and are two-domain proteins, with a catalytic domain and a second domain for binding to the nicotinamide cofactor, either NAD(H) or NADP(H) (4, 5). They contain 0, 1, or 2 zinc atoms (11). When zinc is present, it is involved in catalysis at the active site.

Based on phylogenetic and sequence analysis, the members of the MDR superfamily can be further divided into more closely related subgroups (4, 5). In families which are widespread from prokaryotes to eukaryotes, some members appear conserved across all species, while others appear to be due to lineage specific duplications. Some subgroups are only found in certain taxa. S. cerevisiae contains fifteen (4) or twenty-one (5) members of the MDR superfamily, listed below. The difference in number is due to six sequences that were included as members of the quinone oxidoreductase family by Riveros-Rosas et al. (5) but not by Nordling et al. (4).

Zinc-containing enzyme groups:
- PDH; "polyol" dehydrogenase family - BDH1, BDH2, SOR1, SOR2, XYL2
- ADH; class III alcohol dehydrogenase family - SFA1
- Y-ADH; "yeast" alcohol dehydrogenase family - ADH1, ADH2, ADH3, ADH5
- CADH; cinnamyl alcohol dehydrogenase family - ADH6, ADH7

Non-zinc-containing enzyme groups:
- NRBP; nuclear receptor binding protein (5) or MRF; mitochondrial respiratory function (4) family - ETR1
- QOR; quinone oxidoreductase family - ZTA1 (4, 5), AST1, AST2, YCR102C, YLR460C, YMR152W, YNL134C (5)
- LTD; leukotriene B4 dehydrogenases - YML131W
- ER; enoyl reductases (5) or ACR; acyl-CoA reductase (4) family - no members in S. cerevisiae

Last updated: 2008-08-19 Contact SGD

References cited on this page View Complete Literature Guide for XYL2
1) Richard P, et al.  (1999) Evidence that the gene YLR070c of Saccharomyces cerevisiae encodes a xylitol dehydrogenase. FEBS Lett 457(1):135-8
2) Toivari MH, et al.  (2004) Endogenous xylose pathway in Saccharomyces cerevisiae. Appl Environ Microbiol 70(6):3681-6
3) de Groot PW, et al.  (2001) A genomic approach for the identification and classification of genes involved in cell wall formation and its regulation in Saccharomyces cerevisiae. Comp Funct Genomics 2(3):124-42
4) Nordling E, et al.  (2002) Medium-chain dehydrogenases/reductases (MDR). Family characterizations including genome comparisons and active site modeling. Eur J Biochem 269(17):4267-76
5) Riveros-Rosas H, et al.  (2003) Diversity, taxonomy and evolution of medium-chain dehydrogenase/reductase superfamily. Eur J Biochem 270(16):3309-34
6) Seiboth B, et al.  (2003) D-xylose metabolism in Hypocrea jecorina: loss of the xylitol dehydrogenase step can be partially compensated for by lad1-encoded L-arabinitol-4-dehydrogenase. Eukaryot Cell 2(5):867-75
7) Eliasson A, et al.  (2000) Anaerobic xylose fermentation by recombinant Saccharomyces cerevisiae carrying XYL1, XYL2, and XKS1 in mineral medium chemostat cultures. Appl Environ Microbiol 66(8):3381-6
8) Zhang J, et al.  (2008) Construction of a Recombinant S. cerevisiae Expressing a Fusion Protein and Study on the Effect of Converting Xylose and Glucose to Ethanol. Appl Biochem Biotechnol 150(2):185-92
9) Toivari MH, et al.  (2007) Metabolic Engineering of Saccharomyces cerevisiae for Conversion of D-Glucose to Xylitol and Other Five-Carbon Sugars and Sugar Alcohols. Appl Environ Microbiol 73(17):5471-6
10) Jornvall H, et al.  (1981) Alcohol and polyol dehydrogenases are both divided into two protein types, and structural properties cross-relate the different enzyme activities within each type. Proc Natl Acad Sci U S A 78(7):4226-30
11) Persson B, et al.  (1999) Bioinformatics in studies of SDR and MDR enzymes. Adv Exp Med Biol 463():373-7