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Mo Q, Mao A, Li Y, Shi G. Substrate inactivation of bacterial L-aspartate α-decarboxylase from Corynebacterium jeikeium K411 and improvement of molecular stability by saturation mutagenesis. World J Microbiol Biotechnol 2019; 35:62. [PMID: 30923994 DOI: 10.1007/s11274-019-2629-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 03/08/2019] [Indexed: 12/28/2022]
Abstract
Bacterial L-aspartate α-decarboxylase (PanD) is a potential biocatalyst for the green production of β-alanine, an important block chemical for manufacturing nitrogen-containing chemicals in bio-refinery field. It was reported that the poor catalytic stability caused by substrate inactivation limited the large-scale application. Here, we investigated the characters of inactivation by L-aspartate of PanD from Corynebacterium jeikeium (PDCjei), and found that L-aspartate induced a time-, and concentration-dependent inactivation of PDCjei with the values of KI and kinact being 288.4 mM and 0.235/min, respectively. To improve the catalytic stability of PDCjei, conserved amino acid residues essential to catalytic stability were analyzed by comparing the discrepancy in the observed inactivation rate of various sources. By an efficient colorimetric high-throughput screening method, four mutants with 3.18-24.69% higher activity were obtained from mutant libraries. Among them, the best mutation (R3K) also performed 66.38% higher catalytic stability than the wild type, showing great potential for industrial bio-production of β-alanine.
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Affiliation(s)
- Qin Mo
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - An Mao
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Youran Li
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Guiyang Shi
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China.
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China.
- Jiangsu Provincial Research Center for Bioactive Product Processing Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China.
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Mo Q, Li Y, Wang J, Shi G. Identification of mutations restricting autocatalytic activation of bacterial L-aspartate α-decarboxylase. Amino Acids 2018; 50:1433-1440. [PMID: 30073608 DOI: 10.1007/s00726-018-2620-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 07/12/2018] [Indexed: 11/30/2022]
Abstract
Bacterial L-aspartate α-decarboxylase (PanD) specifically catalyzes the decarboxylation of L-aspartic acid to β-alanine. It is translated as an inactive pro-protein, then processed by self-cleavage to form two small subunits with catalytic activity. There is a significant difference in the efficiency of this process among the reported PanDs, while the structural basis remains unclear. More PanDs with known sequences and characterized properties are needed to shed light on the molecular basis of the self-cleavage process. In this study, PanD genes from 33 selected origins were synthesized and expressed; using purified recombinant enzymes, their self-processing properties were characterized and classified. Three classes of PanDs were acquired based on their self-cleavage efficiency. Combined with the phylogenetic analysis and structure comparison, sited-directed mutagenesis was performed to investigate the effects of four mutants on self-processing. In comparison with the wild-type (96.4%), the self-cleavage efficiencies of mutants V23E, I26C, T27A, and E56S were decreased to 90.5, 83.6, 74.4 and 81.2%, respectively. The results indicated that residues of V23, I26, T27 and E56 were critical to the self-cleavage processing of PanDs. This work provided further understanding to the self-cleavage processing of PanDs, which may contribute to protein engineering of the enzyme.
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Affiliation(s)
- Qin Mo
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China.,School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Youran Li
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China.,School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Junhua Wang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China.,School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Guiyang Shi
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi, 214122, Jiangsu, China. .,School of Biotechnology, Jiangnan University, Wuxi, 214122, Jiangsu, China.
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