Protein engineering of α-ketoisovalerate decarboxylase for improved isobutanol production in Synechocystis PCC 6803

作者：Rui Miao, Hao Xie, Felix M. Ho, Peter Lindblad · 发表于：Metabolic Engineering · 年份：2018 · DOI：10.1016/j.ymben.2018.02.014 · 被引用次数：61 · 研究领域：Biochemical Acid Research Studies、Microbial Metabolic Engineering and Bioproduction、Photosynthetic Processes and Mechanisms

Protein engineering is a powerful tool to modify e.g. protein stability, activity and substrate selectivity. Heterologous expression of the enzyme α-ketoisovalerate decarboxylase (Kivd) in the unicellular cyanobacterium Synechocystis PCC 6803 results in cells producing isobutanol and 3-methyl-1-butanol, with Kivd identified as a potential bottleneck. In the present study, we used protein engineering of Kivd to improve isobutanol production in Synechocystis PCC 6803. Isobutanol is a flammable compound that can be used as a biofuel due to its high energy density and suitable physical and chemical properties. Single replacement, either Val461 to isoleucine or Ser286 to threonine, increased the Kivd activity significantly, both in vivo and in vitro resulting in increased overall production while isobutanol production was increased more than 3-methyl-1-butanol production. Moreover, among all the engineered strains examined, the strain with the combined modification V461I/S286T showed the highest (2.4 times) improvement of isobutanol-to-3M1B molar ratio, which was due to a decrease of the activity towards 3M1B production. Protein engineering of Kivd resulted in both enhanced total catalytic activity and preferential shift towards isobutanol production in Synechocystis PCC 6803.