title: Expression of xylA genes encoding xylose isomerases from Escherichia coli and Streptomyces coelicolor in the methylotrophic yeast Hansenula polymorpha.
abstract: The thermotolerant methylotrophic yeast Hansenula polymorpha is able to ferment xylose to ethanol at high temperatures. H. polymorpha xylose reductase and xylitol dehydrogenase are involved during the first steps of this fermentation. In this article, expression of bacterial xylA genes coding for xylose isomerases from Escherichia coli or Streptomyces coelicolor in the yeast H. polymorpha was shown. The expression was achieved by integration of the xylA genes driven by the promoter of the H. polymorpha glyceraldehyde-3-phosphate dehydrogenase gene ( HpGAP) into the H. polymorpha genome. Expression of the bacterial xylose isomerase genes restored the ability of the H. polymorpha Deltaxyl1 mutant to grow in a medium with xylose as the sole carbon source. This mutant has a deletion of the XYL1 gene encoding xylose reductase and is not able to grow in the xylose medium. The H. polymorpha Deltaxyl1(xylA) transformants displayed xylose isomerase activities, which were near 20% of that of the bacterial host strain. The transformants did not differ from the yeast wild-type strain with respect to ethanol production in xylose medium.
authors.affiliation: Institute of Cell Biology, NAS of Ukraine, Drahomanov Street 14/16, Lviv 79005, Ukraine.
authors.forename: Andriy Y
authors.initials: AY
authors.lastname: Voronovsky
authors.forename: Olena B
authors.initials: OB
authors.lastname: Ryabova
authors.forename: Olena V
authors.initials: OV
authors.lastname: Verba
authors.forename: Olena P
authors.initials: OP
authors.lastname: Ishchuk
authors.forename: Kostyantyn V
authors.initials: KV
authors.lastname: Dmytruk
authors.forename: Andriy A
authors.initials: AA
authors.lastname: Sibirny
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D000431:Ethanol / Q000378:metabolism; D005818:Genetic Engineering; D010843:Pichia / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D048372:Streptomyces coelicolor / Q000235:genetics; D014994:Xylose / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D000431:Ethanol; D014994:Xylose; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase