title: High-level functional expression of a fungal xylose isomerase: the key to efficient ethanolic fermentation of xylose by Saccharomyces cerevisiae?
abstract: Evidence is presented that xylose metabolism in the anaerobic cellulolytic fungus Piromyces sp. E2 proceeds via a xylose isomerase rather than via the xylose reductase/xylitol-dehydrogenase pathway found in xylose-metabolising yeasts. The XylA gene encoding the Piromyces xylose isomerase was functionally expressed in Saccharomyces cerevisiae. Heterologous isomerase activities in cell extracts, assayed at 30 degrees C, were 0.3-1.1 micromol min(-1) (mg protein)(-1), with a Km for xylose of 20 mM. The engineered S. cerevisiae strain grew very slowly on xylose. It co-consumed xylose in aerobic and anaerobic glucose-limited chemostat cultures at rates of 0.33 and 0.73 mmol (g biomass)(-1) h(-1), respectively.
authors.affiliation: Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors.forename: Marko
authors.initials: M
authors.lastname: Kuyper
authors.forename: Harry R
authors.initials: HR
authors.lastname: Harhangi
authors.forename: Ann Kristin
authors.initials: AK
authors.lastname: Stave
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Winkler
authors.forename: Mike S M
authors.initials: MS
authors.lastname: Jetten
authors.forename: Wim T A M
authors.initials: WT
authors.lastname: de Laat
authors.forename: Jan J J
authors.initials: JJ
authors.lastname: den Ridder
authors.forename: Huub J M
authors.initials: HJ
authors.lastname: Op den Camp
authors.forename: Johannes P
authors.initials: JP
authors.lastname: van Dijken
authors.forename: Jack T
authors.initials: JT
authors.lastname: Pronk
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism*; D000693:Anaerobiosis; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D015870:Gene Expression; D020089:Piromyces / Q000201:enzymology / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
chemical_list: D000431:Ethanol; D014994:Xylose; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase