Abstract
Genes encoding l-arabinose transporters in Kluyveromyces
marxianus and Pichia guilliermondii were identified by
functional complementation of Saccharomyces cerevisiae
whose growth on l-arabinose was dependent on a
functioning l-arabinose transporter, or by screening a
differential display library, respectively. These
transporters also transport d-xylose and were designated
KmAXT1 (arabinose-xylose transporter) and PgAXT1,
respectively. Transport assays using l-arabinose showed
that KmAxt1p has Km 263mm and Vmax 57nm/mg/min, and
PgAxt1p has Km 0.13mm and Vmax 18nm/mg/min. Glucose,
galactose and xylose significantly inhibit l-arabinose
transport by both transporters. Transport assays using
d-xylose showed that KmAxt1p has Km 27mm and Vmax
3.8nm/mg/min, and PgAxt1p has Km 65mm and Vmax
8.7nm/mg/min. Neither transporter is capable of
recovering growth on glucose or galactose in a S.
cerevisiae strain deleted for hexose and galactose
transporters. Transport kinetics of S. cerevisiae Gal2p
showed Km 371mm and Vmax 341nm/mg/min for l-arabinose,
and Km 25mm and Vmax 76nm/mg/min for galactose. Due to
the ability of Gal2p and these two newly characterized
transporters to transport both l-arabinose and d-xylose,
one scenario for the complete usage of biomass-derived
pentose sugars would require only the low-affinity,
high-throughput transporter Gal2p and one additional
high-affinity general pentose transporter, rather than
dedicated d-xylose or l-arabinose transporters.
Additionally, alignment of these transporters with other
characterized pentose transporters provides potential
targets for substrate recognition engineering.
Original language | English |
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Pages (from-to) | 615-628 |
Journal | Yeast |
Volume | 32 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- arabinose
- xylose
- transport
- yeast
- GAL2