The Penicillium chrysogenum transporter PcAraT enables high-affinity, glucose-insensitive l-arabinose transport in Saccharomyces cerevisiae

摘要: 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 low concentrations of l-arabinose, an important rate-controlling step complete conversion these feedstocks engineered pentose-metabolizing S. strains. Chemostat-based transcriptome analysis yielded 16 putative sugar genes filamentous fungus Penicillium chrysogenum whose transcript were least threefold higher l-arabinose-limited cultures than d-glucose-limited and ethanol-limited cultures. Of five genes, that encoded transport proteins showed over 30-fold level l-arabinose-grown compared to d-glucose-grown cultures, only one (Pc20g01790) restored growth on l-arabinose upon expression l-arabinose-fermenting strain which endogenous transporter, GAL2, had been deleted. Sugar assays indicated this fungal designated as PcAraT, a high-affinity (Km = 0.13 mM), high-specificity l-arabinose-proton symporter does not d-xylose or An l-arabinose-metabolizing GAL2 was replaced PcaraT 450-fold lower residual substrate chemostat congenic import depended (4.2 × 10−3 1.8 g L−1, respectively). Inhibition most abundant sugars hydrolysates, d-glucose far less pronounced observed with Gal2. Expression PcAraT hexose-phosphorylation-deficient, enabled media supplemented both 20 g L−1 d-glucose, completely same condition high affinity specificity for combined limited sensitivity inhibition d-xylose, make valuable application metabolic engineering strategies aimed strains efficient