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Du H, Hu RW, Zhao HM, Huang HB, Xiang L, Liu BL, Feng NX, Li H, Li YW, Cai QY, Mo CH. Mechanistic insight into esterase-catalyzed hydrolysis of phthalate esters (PAEs) based on integrated multi-spectroscopic analyses and docking simulation. JOURNAL OF HAZARDOUS MATERIALS 2021; 408:124901. [PMID: 33360702 DOI: 10.1016/j.jhazmat.2020.124901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/01/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
A novel PAE-hydrolyzing esterase (named Hyd) gene was screened from the genomic library of Rhodococcus sp. 2G and was successfully expressed in heterologous E. coli, which was defined as a new family of esterolytic enzymes. The purified Hyd could efficiently degrade various PAEs, displaying high activity and stability with a broad range of pH (4-10) and temperature (20-60 °C). Interaction mechanism of Hyd with dibutyl phthalate (DBP) was investigated by integrated multi-spectroscopic and docking simulation methods. Fluorescence and UV-vis spectra revealed that DBP could quench the fluorescence of Hyd through a static quenching mechanism. The results from synchronous fluorescence and CD spectra confirmed that the DBP binding to Hyd triggered conformational and micro-environmental changes of Hyd, which were characterized by increased stretching extent and random coil, and decreased α-helix and β-sheet. Molecular docking study showed that DBP could be bound to the cavity of Hyd with hydrogen bonding and hydrophobic interaction. A novel and distinctive catalytic mechanism was proposed: two key residues Thr190 and Ser191 might catalyze the hydrolysis of DBP, instead of the conserved catalytic triad (Ser-His-Asp) reported elsewhere, which was confirmed by site-directed mutagenesis.
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Affiliation(s)
- Huan Du
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Rui-Wen Hu
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Hai-Ming Zhao
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
| | - He-Biao Huang
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Lei Xiang
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Bai-Lin Liu
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Nai-Xian Feng
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Hui Li
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Yan-Wen Li
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Quan-Ying Cai
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
| | - Ce-Hui Mo
- Guangdong Provincial Research Center for Environment Pollution Control and Remediation Materials, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
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