Xu L, Wang LC, Su BM, Xu XQ, Lin J. Multi-enzyme cascade for improving β-hydroxy-α-amino acids production by engineering
L-threonine transaldolase and combining acetaldehyde elimination system.
Bioresour Technol 2020;
310:123439. [PMID:
32361648 DOI:
10.1016/j.biortech.2020.123439]
[Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 06/11/2023]
Abstract
L-threonine transaldolase(PsLTTA) could asymmetric synthesize β-hydroxy-α-amino acids (HAAs) with excellentstereoselectivity, while the poor yield limited its further application. Here we provided a combinatorial strategy to improve HAAs production, by directed evolution of PsLTTA towards enhanced activity and introducing an acetaldehyde elimination system to avoid acetaldehyde over-accumulation. A novel high throughput screening (HTS) method for evaluating PsLTTA activity was developed andapplied for directed evolution of PsLTTA. Subsequently, we co-expressedalcohol dehydrogenase andformate dehydrogenase to construct an acetaldehyde elimination system toremove acetaldehyde inhibition.Moreover, the above positive strategies were integrated. As a result,the (2S,3R)-p-methylsulfonyl phenylserine yield reached 154.0 mM andwith 94.6% devalue, the highest productivity and stereoselectivity of (2S,3R)-HAAs reported by enzymatic synthesis so far. Taken together, our studies provided an efficient and green route for chiral synthesis of (2S,3R)-HAAs, which might contribute to the industrialization production of these useful building blocks.
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