Directed evolution of tyrosine ammonia-lyase to improve the production of p-coumaric acid in Escherichia coli.

Yanan Huo; Fengli WU; Guotian Song; Ran TU; Wujiu Chen; Erbing Hua; Qinhong Wang

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Directed evolution of tyrosine ammonia-lyase to improve the production of p-coumaric acid in Escherichia coli.

Author: Yanan HUO ¹ ; Fengli WU ² ; Guotian SONG ² ; Ran TU ² ; Wujiu CHEN ² ; Erbing HUA ¹ ; Qinhong WANG ²
Author Information

1. College of Biotechnology, Tianjin University of Science & Technology, Tianjin 300457, China.
2. CAS Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
Publication Type:Journal Article
Keywords: Escherichia coli; biosynthesis; directed evolution; p-coumaric acid; tyrosine ammonia-lyase
MeSH: Ammonia-Lyases/genetics*; Escherichia coli/genetics*; Propionates; Rhodotorula; Tyrosine/genetics*
From: Chinese Journal of Biotechnology 2020;36(11):2367-2376
CountryChina
Language:Chinese
Abstract: p-coumaric acid is an important natural phenolic compound with a variety of pharmacological activities, and also a precursor for the biosynthesis of many natural compounds. It is widely used in foods, cosmetics and medicines. Compared with the chemical synthesis and plant extraction, microbial production of p-coumaric acid has many advantages, such as energy saving and emission reduction. However, the yield of p-coumaric acid by microbial synthesis is too low to meet the requirements of large-scale industrial production. Here, to further improve p-coumaric acid production, the directed evolution of tyrosine ammonia lyase (TAL) encoded by Rhodotorula glutinis tal gene was conducted, and a high-throughput screening method was established to screen the mutant library for improve the property of TAL. A mutant with a doubled TAL catalytic activity was screened from about 10,000 colonies of the mutant library. There were three mutational amino acid sites in this TAL, namely S9Y, A11N, and E518A. It was further verified by a single point saturation mutation. When S9 was mutated to Y, I or N, or A11 was mutated to N, T or Y, the catalytic activity of TAL increased by more than 1-fold. Through combinatorial mutation of three types of mutations at the S9 and A11, the TAL catalytic activity of S9Y/A11N or S9N/A11Y mutants were significantly higher than that of other mutants. Then, the plasmid containing S9N/A11Y mutant was transformed into CP032, a tyrosine-producing E. coli strain. The engineered strain produced 394.2 mg/L p-coumaric acid, which is 2.2-fold higher than that of the control strain, via shake flask fermentation at 48 h. This work provides a new insight for the biosynthesis study of p-coumaric acid.