Journal Article Crucial role of 4-deoxy-L-erythro-5-hexoseulose uronate reductase for alginate utilization revealed by adaptive evolution in engineered Saccharomyces cerevisiae

Matsuoka, Fumiya  ,  Hirayama, Makoto  ,  Kashihara, Takayuki  ,  Tanaka, Hideki  ,  Hashimoto, Wataru  ,  Murata, Kousaku  ,  Kawai, Shigeyuki

72017-06-23 , Springer Nature
代謝改変酵母のアルギン酸モノマー代謝能向上メカニズムの解明--国産海洋バイオマス資源から代替ガソリンや合成ゴム原料を生産するための重要な第一歩--. 京都大学プレスリリース. 2017-06-26.
In brown macroalgae, alginate and D-mannitol are promising carbohydrates for biorefinery. Saccharomyces cerevisiae is widely used as a microbial cell factory, but this budding yeast is unable to utilize either alginate or D-mannitol. Alginate can be depolymerized by both endo-type and exo-type alginate lyases, yielding a monouronate, 4-deoxy-L-erythro-5-hexoseulose uronate (DEH), a key intermediate in the metabolism of alginate. Here, we constructed engineered two S. cerevisiae strains that are able to utilize both DEH and D-mannitol on two different strain backgrounds, and we also improved their aerobic growth in a DEH liquid medium through adaptive evolution. In both evolved strains, one of the causal mutations was surprisingly identical, a c.50A > G mutation in the codon-optimized NAD(P)H-dependent DEH reductase gene, one of the 4 genes introduced to confer the capacity to utilize DEH. This mutation resulted in an E17G substitution at a loop structure near the coenzyme-binding site of this reductase, and enhanced the reductase activity and aerobic growth in both evolved strains. Thus, the crucial role for this reductase reaction in the metabolism of DEH in the engineered S. cerevisiae is demonstrated, and this finding provides significant information for synthetic construction of a S. cerevisiae strain as a platform for alginate utilization.

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