High impact information on XYL2

• Two copies of the XYL2 gene encoding XDH in the diploid yeast Candida tropicalis were sequentially disrupted using the Ura-blasting method [1].
• Following a sequential search for gene targets, we repeated the complementation enrichment process in a XYL1 XYL2 XYL3 background and identified 15 fast-growing transformants, all of which harbored the same plasmid [2].
• To further investigate whether the newly identified PsTAL1 ORF is responsible for the enhanced-growth phenotype, we constructed an expression cassette containing the PsTAL1 ORF under the control of a constitutive promoter and transformed it into an S. cerevisiae recombinant expressing XYL1, XYL2, and XYL3 [2].
• We found that S. cerevisiae can grow on D-xylose when only the endogenous genes GRE3 (YHR104w), coding for a nonspecific aldose reductase, and XYL2 (YLR070c, ScXYL2), coding for a xylitol dehydrogenase (XDH), are overexpressed under endogenous promoters [3].
• The S. cerevisiae genetic background included single integrated copies of P. stipitis XYL1 and XYL2 driven by the S. cerevisiae TDH1 promoter [4].

Biological context of XYL2

• Directed mutagenesis has been used to identify a set of amino acids in the Pichia stipitis xylitol dehydrogenase, encoded by the xylitol dehydrogenase gene XYL2, which is involved in specific NAD binding [5].
• Copy numbers of XYL2 were varied either by integrating XYL2 into the chromosome or by transforming cells with XYL2 in a multicopy vector [6].
• The XYL2 open-reading frame codes for a protein of 363 amino acids with a predicted molecular mass of 38.5 kDa [7].
• The genomic XYL2 gene was isolated and the nucleotide sequence of the 1089 bp structural gene, and of adjacent non-coding regions, was determined [7].

Associations of XYL2 with chemical compounds

• Anaerobic xylose fermentation by recombinant Saccharomyces cerevisiae carrying XYL1, XYL2, and XKS1 in mineral medium chemostat cultures [8].
• Saccharomyces cerevisiae is able to ferment xylose, when engineered with the enzymes xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) [9].
• The mutagenized XYL2 gene could still mediate growth of Saccharomyces cerevisiae transformants on xylose minimal-medium plates when expressed together with the xylose reductase gene (XYL1) [5].
• Secretion of xylulose by strains with multicopy XYL2 and elevated XDH supports the hypothesis that D-xylulokinase limits metabolic flux in recombinant S. cerevisiae [6].
• Xylitol dehydrogenase encoded by gene XYL2 from Pichia stipitis is a member of the medium-chain alcohol dehydrogenase family, as evidenced by the domain organization and a distant homology (24% residue identity with the human class I gamma 1 alcohol dehydrogenase) [10].

Regulatory relationships of XYL2

• A XYL1- and XYL2-containing S. cerevisiae strain overexpressing TAL1 (S104-TAL) showed considerably enhanced growth on xylose compared with a strain containing only XYL1 and XYL2 [11].

Other interactions of XYL2

• In order to enhance xylose utilisation in the XYL1-, XYL2-containing S. cerevisiae strains, the native genes encoding transketolase and transaldolase were also overexpressed [12].

References