Title |
The Penicillium chrysogenum transporter PcAraT enables high-affinity, glucose-insensitive l-arabinose transport in Saccharomyces cerevisiae
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Published in |
Biotechnology for Biofuels and Bioproducts, March 2018
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DOI | 10.1186/s13068-018-1047-6 |
Pubmed ID | |
Authors |
Jasmine M. Bracher, Maarten D. Verhoeven, H. Wouter Wisselink, Barbara Crimi, Jeroen G. Nijland, Arnold J. M. Driessen, Paul Klaassen, Antonius J. A. van Maris, Jean-Marc G. Daran, Jack T. Pronk |
Abstract |
l-Arabinose occurs at economically relevant levels in lignocellulosic hydrolysates. Its low-affinity uptake via the Saccharomyces cerevisiae Gal2 galactose transporter is inhibited by d-glucose. Especially at low concentrations of l-arabinose, uptake is an important rate-controlling step in the complete conversion of these feedstocks by engineered pentose-metabolizing S. cerevisiae strains. Chemostat-based transcriptome analysis yielded 16 putative sugar transporter genes in the filamentous fungus Penicillium chrysogenum whose transcript levels were at least threefold higher in l-arabinose-limited cultures than in d-glucose-limited and ethanol-limited cultures. Of five genes, that encoded putative transport proteins and showed an over 30-fold higher transcript level in l-arabinose-grown cultures compared to d-glucose-grown cultures, only one (Pc20g01790) restored growth on l-arabinose upon expression in an engineered l-arabinose-fermenting S. cerevisiae strain in which the endogenous l-arabinose transporter, GAL2, had been deleted. Sugar transport assays indicated that this fungal transporter, designated as PcAraT, is a high-affinity (Km = 0.13 mM), high-specificity l-arabinose-proton symporter that does not transport d-xylose or d-glucose. An l-arabinose-metabolizing S. cerevisiae strain in which GAL2 was replaced by PcaraT showed 450-fold lower residual substrate concentrations in l-arabinose-limited chemostat cultures than a congenic strain in which l-arabinose import depended on Gal2 (4.2 × 10-3 and 1.8 g L-1, respectively). Inhibition of l-arabinose transport by the most abundant sugars in hydrolysates, d-glucose and d-xylose was far less pronounced than observed with Gal2. Expression of PcAraT in a hexose-phosphorylation-deficient, l-arabinose-metabolizing S. cerevisiae strain enabled growth in media supplemented with both 20 g L-1 l-arabinose and 20 g L-1 d-glucose, which completely inhibited growth of a congenic strain in the same condition that depended on l-arabinose transport via Gal2. Its high affinity and specificity for l-arabinose, combined with limited sensitivity to inhibition by d-glucose and d-xylose, make PcAraT a valuable transporter for application in metabolic engineering strategies aimed at engineering S. cerevisiae strains for efficient conversion of lignocellulosic hydrolysates. |
Mendeley readers
Geographical breakdown
Country | Count | As % |
---|---|---|
Unknown | 62 | 100% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Researcher | 9 | 15% |
Student > Bachelor | 7 | 11% |
Student > Ph. D. Student | 7 | 11% |
Professor > Associate Professor | 6 | 10% |
Student > Master | 6 | 10% |
Other | 6 | 10% |
Unknown | 21 | 34% |
Readers by discipline | Count | As % |
---|---|---|
Biochemistry, Genetics and Molecular Biology | 19 | 31% |
Agricultural and Biological Sciences | 11 | 18% |
Engineering | 3 | 5% |
Chemical Engineering | 2 | 3% |
Nursing and Health Professions | 1 | 2% |
Other | 4 | 6% |
Unknown | 22 | 35% |