The capacity of yeasts to assimilate xylose or arabinose is strongly dependent on plasma membrane transport proteins. Because pentoses comprise a substantial proportion of available sugars in lignocellulosic hydrolysates, their utilisation is centrally important for the development of second generation biorefineries. Relatively few native pentose transporters have been studied and there is intense interest in expanding the repertoire. To aid the identification of novel transporters, we developed a screening platform in the native pentose-utilising yeast Kluyveromyces marxianus. This involved the targeted deletion of twelve transporters of the major facilitator superfamily (MFS) and application of a synthetic biology pipeline for rapid testing of candidate pentose transporters. Using this K. marxianus ΔPT platform, we identified several K. marxianus putative xylose or arabinose transporter proteins that recovered a null strain's ability to growth on these pentoses. Four proteins of the HGT-family were able to support growth in media with high or low concentrations of either xylose or arabinose, while six HXT-like proteins displayed growth only at high xylose concentrations, indicating solely low affinity transport activity. The study offers new insights into the evolution of sugar transporters in yeast and expands the set of native pentose transporters for future functional and biotechnological studies.

中文翻译：

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使用新筛选平台鉴定马克斯克鲁维酵母中新型戊糖转运蛋白

酵母同化木糖或阿拉伯糖的能力强烈依赖于质膜转运蛋白。由于戊糖在木质纤维素水解物中含有相当大比例的可用糖，因此它们的利用对于第二代生物精炼厂的发展至关重要。研究了相对较少的天然戊糖转运蛋白，并且对扩展库有浓厚的兴趣。为了帮助鉴定新型转运蛋白，我们在天然利用戊糖的酵母克鲁维酵母马克斯酵母中开发了一个筛选平台。这涉及有针对性地删除主要促进剂超家族 (MFS) 的 12 个转运蛋白，并应用合成生物学管道快速测试候选戊糖转运蛋白。使用这个K. marxianus ΔPT 平台，我们鉴定了几种K. marxianus推定的木糖或阿拉伯糖转运蛋白，它们恢复了无效菌株在这些戊糖上的生长能力。HGT 家族的四种蛋白质能够支持在高浓度或低浓度木糖或阿拉伯糖的培养基中生长，而六种 HXT 样蛋白质仅在高木糖浓度下显示生长，这表明亲和转运活性很低。该研究为酵母中糖转运蛋白的进化提供了新的见解，并为未来的功能和生物技术研究扩展了天然戊糖转运蛋白的集合。