Publications
SSRNJan 2025 DOI:
10.2139/ssrn.5171206

All You Can Eat Yeast: Substituting Hexose Transporters with Atsweet7 Alleviates Glucose Repression, Enabling Simultaneous Utilization of Sugars in Renewable Feedstocks

Kuanyshev, Nurzhan; Dai, Degaulle; Kim, Jungyeon; Kang, Nam Kyu; Cheng, Ming‐Hsun; Singh, Vijay Pratap; Jin, Yong‐Su
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Abstract
Yeast sugar transporters have highly evolved for preferential glucose transport, a 4 significant roadblock for utilizing non-glucose sugars in renewable feedstocks such as 5 lignocellulosic biomass. To enable simultaneous transport of glucose and xylose, 6 primary constituents of plant cell wall hydrolysates, in Saccharomyces cerevisiae, 7 SWEET7p from Arabidopsis thaliana was introduced into an engineered S. cerevisiae 8 capable of fermenting xylose. Specifically, we replaced seven major hexose 9 transporters (HXT1-7) with AtSWEET7 to construct an engineered S. cerevisiae 10 (NKSW7-1) which relies solely on SWEET7p for sugar transport. Remarkably, NKSW7- 11 1 exhibited no glucose repression, simultaneously co-fermenting glucose, mannose, 12 fructose, and xylose not only in a synthetic medium, but also all sugars in bagasse 13 hydrolysate and cane juice mixtures. Continuous culture experiments with NKSW7-1 14 further demonstrated the co-consuming phenotype and alleviation of glucose repression 15 by the SWEET7p expressing S. cerevisiae. In addition to hexose and pentose, the 16 NKSW7-1 strain consumed xylitol as a carbon source. Transcriptomic and metabolomic 17 analysis revealed that the replacement of HXT1-7 with AtSWEET7 led to systemwide 18 reprogramming of the central carbon metabolism, with glucose-repressed genes 19 activated even at high glucose concentrations. This broad transport capacity of 20 SWEET7p, coupled with drastic impact on sugar metabolism, holds significant promise 21 for achieving simultaneous co-utilization of multiple sugars in renewable feedstocks. 22 These findings pave the way for the production of high-value bioproducts beyond 23 ethanol, particularly from emerging, underutilized, and renewable feedstocks.
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