High-level functional expression of a fungal xylose isomerase: the key to efficient ethanolic fermentation of xylose by Saccharomyces cerevisiae?
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.
Kuyper
Marko
M
Kluyver Laboratory of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
Harhangi
Harry R
HR
Stave
Ann Kristin
AK
Winkler
Aaron A
AA
Jetten
Mike S M
MS
de Laat
Wim T A M
WT
den Ridder
Jan J J
JJ
Op den Camp
Huub J M
HJ
van Dijken
Johannes P
JP
Pronk
Jack T
JT
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*
D000431:Ethanol; D014994:Xylose; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase