WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
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2022
·Vol. 38
·期 6
·1-10
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IF 4.253
Liang YaoYao,Luo Juan,Yang Chenhao,Guo Shuning,Zhang Bowen,Chen Fengqianrui,Su Kairui,Zhang Yulong,Dong Yi,Wang Zhihao,Fu Hongda,Sui Guangchao,Wang Pengchao
Hydroxy-mandelic acid (HMA) is widely applied in pharmaceuticals, food and cosmetics. In this study, we aimed to develop an allosteric transcription factors (aTFs) based biosensor for HMA. PobR, an aTF for HMA analog 4-hydroxybenzoic acid, was used to alter its selectivity and create novel aTFs responsive to HMA by directed evolution. We established a PobR mutant library with a capacity of 550,000 mutants using error-prone PCR and Megawhop PCR. Through our screening, two mutants were obtained with responsiveness to HMA. Analysis of each missense mutation indicating residues 122–126 were involved in its PobR ligand specificity. These results showed the effectiveness of directed evolution in switching the ligand specificity of a biosensor and improving HMA production.
研究领域:
生物技术
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分子生物学
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化学生物学
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产品关联
DOI
PubMed
高影响因子
ENZYME AND MICROBIAL TECHNOLOGY
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2020
·
IF 3.448
Zelong Li,Runtao Zhu,Yongqi Liu,Jiaqi Li,Haofeng Gao,Nan Hu
L-theanine, a unique amino acid in green tea with health benefits, can be enzymatically synthesized by γ-glutamyltranspeptidase (γ-GT; EC 2.3.2.2). Here, a salt-tolerant γ-glutamyltranspeptidase from a marine bacterium Bacillus amyloliquefaciens was expressed in Escherichia. coli BL21 (DE3) and was shown to be optimally active at 55 °C, pH 8.5 and alkali stable. A mutant, with higher transpeptidation activity, was obtained following two rounds of directed evolution using error-prone PCR and site-saturation mutagenesis. The mutation increased the ratio of transpeptidation to hydrolysis from 1.6 to 35.6. Additionally, Kinetic analysis exhibited 17.5% decrease of K m , 13.0-fold increase of K cat , and 16.3-fold increase of K cat / K m in mutant V319A/S437 G versus the wild-type. The 3-D modelling analysis revealed a tighter binding pocket in mutant V319A/S437 G. The frequency of hydrogen bond between donor substrate and two residues in the catalytic pocket (Gly437 and Thr375) was enhanced, which stabilized the ligand binding and thus improved the catalytic efficiency. The optimal conditions for the biocatalytic synthesis were determined as pH 10.0, 20 μg mL -1 Ba GT, 200 mM L-glutamine, 2 M ethylamine, and a reaction time of 5 h. The V319A/S437 G mutant was shown to increase the percentage yield of L-theanine from 58% to 83%. These results indicate the great potential of V319A/S437 G in L-theanine production after further study.
研究领域:
生物化学
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生物技术
·
酶学
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产品关联
DOI
PubMed
高影响因子
ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2020
·
IF 4.872
Jiarong Qiu,Haiyan Yang,Yuting Shao,Longxiang Li,Shengwei Sun,Luyao Wang,Yuzhi Tan,Zhihong Xin
Our previous work has reported that EstJ6 was a phthalate-degrading hydrolase. In the study, a random mutant library was constructed by two rounds of error-prone PCR, three mutants (ET1.1, ET2.1, and ET2.2) with enhanced hydrolytic activity against dibutyl phthalate (DBP) were obtained. The best mutant ET2.2, accumulated three amino acid substitutions (Thr91Met, Ala67Val, and Val249Ile) and exhibited 2.8-fold increase enzyme activity and 2.3-fold higher expression level. Meanwhile, compared with EstJ6, ET2.2 showed over 50% improvement in thermostability (at 50 °C for 1 h) and 1.2-fold increase in 50% methanol tolerance. Kinetic parameters analysis revealed that the Km value for ET2.2 decreased by 60% and the kcat/Km value increased by 166%. The molecular docking indicated that the shortening of hydrogen bond between Ser146-OH and DBP-CO, which may led to an increase in enzyme activity and catalytic efficiency, the enhancement of hydrophobicity of hydrophobic pocket was related to the improvement of organic solvents tolerance, and three hydrophobic amino acid substitutions Thr91Met, Ala67Val, and Val249Ile facilitated to improve the thermal stability and organic solvents tolerance. These results confirmed that random mutagenesis was an effective tool for improving enzyme properties and lay a foundation for practical applications of phthalate-degrading hydrolase in biotechnology and industrial fields.
研究领域:
生物化学
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酶工程
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生物技术
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环境科学
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DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2023
·
IF 13.6
Shunlan Li,Dongdong Chen,Ziqing Liu,Shipin Tao,Tianyi Zhang,Yiwen Chen,Lingzhi Bao,Jie Ma,Yuee Huang,Shengmin Xu,Lijun Wu,Shaopeng Chen
Antibiotic abuse is the main reason for the drug resistance of pathogenic bacteria, posing a potential health risk. Antibiotic surveillance is critical for preventing antibiotic contamination. This study aimed to develop a sensitive and broad-spectrum whole-cell biosensor for tetracycline antibiotics (TCs) detection. Wild-type TCs-responsive biosensor was constructed by introducing a tetracycline operon into a sfGFP reporter plasmid. Using error-prone PCR, mutation libraries containing approximately 10 7 variants of the tetracycline repressor (TetR) gene were generated. The tigecycline-senstive mutants were isolated using high-throughput flow cytometric sorting. After 2 rounds of directed evolution, a mutant epS2–22 of TerR was isolated and assembled as a TCs biosensor. The epS2–22 biosensor was more sensitive and broad-spectrum than the wild-type biosensors. The detection limits of the epS2–22 biosensor for seven TCs were 4- to 62-fold lower than the wild-type biosensor (no response to tigecycline). Meanwhile, the epS2–22 biosensor had a shorter detection time and a stronger signal output than the wild type. In addition, the evolved epS2–22 biosensor showed excellent performance in detecting low traces of TCs in environmental water. These results suggest that directed evolution is a powerful tool for developing high-performance whole-cell biosensors, and the evolved epS2–22 biosensors have the potential for wider applications in real-world TCs detection.
研究领域:
生物技术
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微生物学
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环境科学
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产品关联
DOI
PubMed
高影响因子
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