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He N, Wang Z, Lei L, Chen C, Qin Y, Tang J, Dai K, Xu H. Enhancing high-efficient cadmium biosorption of Escherichia coli via cell surface displaying metallothionien CUP1. ENVIRONMENTAL TECHNOLOGY 2024:1-10. [PMID: 39016212 DOI: 10.1080/09593330.2024.2375006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 06/22/2024] [Indexed: 07/18/2024]
Abstract
Cadmium (Cd) is one of the common heavy metal pollutants in soil, which can induce various diseases and pose a serious threat to human health. Metallothioneins (MTs) are well-known for their excellent metal binding ability due to a high content of cysteine, which has great potential for heavy metal chelation. In this study, we used the Escherichia coli (E. coli) surface display system LPP-OmpA to construct a recombinant plasmid pBSD-LCF encoding LPP-OmpA-CUP1-Flag fusion protein. Then we displayed the metallothionein CUP1 from Saccharomyces cerevisiae on E. coli DH5α surface for Cd removing. The feasibility of surface display of metallothionein CUP1 in recombinant E. coli DH5α (pBSD-LCF) by Lpp-OmpA system was proved by flow cytometry and western blot analysis, and the specificity of the fusion protein in the recombinant strain was also verified. The results showed that the Cd2+ resistance capacity of DH5α (pBSD-LCF) was highly enhanced by about 200%. Fourier-transform infrared spectroscopy showed that sulfhydryl and sulfonyl groups were involved in Cd2+ binding to cell surface of DH5α (pBSD-LCF). Meanwhile, Cd removal rate by DH5α (pBSD-LCF) was promoted to 95.2%. Thus, the recombinant strain E. coli DH5α (pBSD-LCF) can effectively chelate environmental metals, and the cell surface expression of metallothionein on E. coli can provide new ideas and directions for heavy metals remediation.
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Affiliation(s)
- Nan He
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu, People's Republic of China
| | - Ziru Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Ling Lei
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Changxuan Chen
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Yixian Qin
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Jingxiang Tang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Kecheng Dai
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
| | - Heng Xu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, People's Republic of China
- Key Laboratory of Environment Protection, Soil Ecological Protection and Pollution Control, Sichuan University and Department of Ecology and Environment of Sichuan, Chengdu, People's Republic of China
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Qian X, Ma C, Zhang H, Liu K. Bioseparation of rare earth elements and high value-added biomaterials applications. Bioorg Chem 2024; 143:107040. [PMID: 38141331 DOI: 10.1016/j.bioorg.2023.107040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/24/2023] [Accepted: 12/15/2023] [Indexed: 12/25/2023]
Abstract
Rare earth elements (REEs) are a group of critical minerals and extensively employed in new material manufacturing. However, separation of lanthanides is difficult because of their similar chemical natures. Current lanthanide leaching and separation methods require hazardous compounds, resulting in severe environmental concerns. Bioprocessing of lanthanides offers an emerging class of tools for REE separation due to mild leaching conditions and highly selective separation scenarios. In the course of biopreparation, engineered microbes not only dissolve REEs from ores but also allow for selective separation of the lanthanides. In this review, we present an overview of recent advances in microbes and proteins used for the biomanufacturing of lanthanides and discuss high value-added applications of REE-derived biomaterials. We begin by introducing the fundamental interactions between natural microbes and REEs. Then we discuss the rational design of chassis microbes for bioleaching and biosorption. We also highlight the investigations on REE binding proteins and their applications in the synthesis of high value-added biomaterials. Finally, future opportunities and challenges for the development of next generation lanthanide-binding biological systems are discussed.
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Affiliation(s)
- Xining Qian
- Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Chao Ma
- Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China; Xiangfu Laboratory, Building 5, No.828 Zhongxing Road, Xitang Town, Jiashan, Jiaxing, Zhejiang 314102, China.
| | - Hongjie Zhang
- Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China; Xiangfu Laboratory, Building 5, No.828 Zhongxing Road, Xitang Town, Jiashan, Jiaxing, Zhejiang 314102, China
| | - Kai Liu
- Engineering Research Center of Advanced Rare Earth Materials (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China; Xiangfu Laboratory, Building 5, No.828 Zhongxing Road, Xitang Town, Jiashan, Jiaxing, Zhejiang 314102, China
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Glab-Ampai K, Mahasongkram K, Chulanetra M, Saenlom T, Thueng-In K, Sookrung N, Chaicumpa W. Human super antibody to viral RNA-dependent RNA polymerase produced by a modified Sortase self-cleave-bacteria surface display system. Microb Cell Fact 2023; 22:260. [PMID: 38110987 PMCID: PMC10726597 DOI: 10.1186/s12934-023-02267-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/09/2023] [Indexed: 12/20/2023] Open
Abstract
BACKGROUND RNA-dependent RNA polymerase (RdRp) is a good target of anti-RNA virus agents; not only it is pivotal for the RNA virus replication cycle and highly conserved among RNA viruses across different families, but also lacks human homolog. Recently, human single-chain antibody (HuscFv) that bound to thumb domain of hepatitis C virus (HCV) RNA-dependent RNA polymerase (functionalized NS5B protein) was produced and engineered into cell-penetrating antibody (super antibody) in the form of cell-penetrating peptide (penetratin, PEN)-linked HuscFv (PEN-HuscFv34). The super antibody was produced and purified from inclusion body (IB) of a pen-huscfv34-vector-transformed Escherichia coli. The super antibody inhibited replication of alpha- and beta- coronaviruses, flaviviruses, and picornaviruses that were tested (broadly effective); thus, it has high potential for developing further towards a pan-anti-RNA virus agent. However, production, purification, and refolding of the super antibody molecules from the bacterial IB are laborious and hurdles to large-scale production. Therefore, in this study, Sortase-self-cleave method and bacteria surface display system were combined and modified for the super antibody production. METHODS AND RESULTS BL21 (DE3) ΔA E. coli, a strain lacking predominant outer membrane protein (OmpA) and ion and OmpT proteases, that displayed a membrane-anchored fusion protein, i.e., chimeric lipoprotein (Lpp')-OmpA', SUMO, Sortase protease, Sortase cleavage site (LPET↓G) and PEN-HuscFv34-6× His was generated. The soluble PEN-HuscFv34-6× His with glycine at the N-terminus could be released from the E. coli surface, simply by incubating the bacterial cells in a Sortase-cleavage buffer. After centrifugation, the G-PEN-HuscFv34-6× His could be purified from the supernatant. The purified G-PEN-HuscFv34-6× retained original cell-penetrating ability (being super antibody) and the broadly effective anti-RNA virus activity of the original IB-derived-PEN-HuscFv34. CONCLUSION The functionalized super antibody to RNA virus RdRp was successfully produced by using combined Sortase self-cleave and bacterial surface display systems with modification. The display system is suitable for downstream processing in a large-scale production of the super antibody. It is applicable also for production of other recombinant proteins in soluble free-folding form.
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Affiliation(s)
- Kantaphon Glab-Ampai
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Kodchakorn Mahasongkram
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Monrat Chulanetra
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Thanatsaran Saenlom
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Kanyarat Thueng-In
- School of Pathology, Translational Medicine Program, Institute of Medicine, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Nitat Sookrung
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
- Biomedical Research Incubation Unit, Department of Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Wanpen Chaicumpa
- Center of Research Excellence in Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
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Identification of Subunits for Novel Universal Vaccines against Three Predominant Serogroups and the Emerging O145 among Avian Pathogenic Escherichia coli by Pan-RV Pipeline. Appl Environ Microbiol 2023; 89:e0106122. [PMID: 36533928 PMCID: PMC9888223 DOI: 10.1128/aem.01061-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Avian pathogenic Escherichia coli, a causative agent of avian colibacillosis, has been causing serious economic losses in the poultry industry. The increase in multidrug-resistant isolates and the complexity of the serotypes of this pathogen, especially the recently reported emergence of a newly predominant serogroup of O145, make the control of this disease difficult. To address this challenge, a high-throughput screening approach, called Pan-RV (Reverse vaccinology based on pangenome analysis), is proposed to search for universal protective antigens against the three traditional serogroups and the newly emerged O145. Using this approach, a total of 61 proteins regarded as probable antigens against the four important serogroups were screened from the core genome of 127 Avian pathogenic Escherichia coli (APEC) genomes, and six were verified by Western blots using antisera. Overall, our research will provide a foundation for the development of an APEC subunit vaccine against avian colibacillosis. Given the exponential growth of whole-genome sequencing (WGS) data, our Pan-RV pipeline will make screening of bacterial vaccine candidates inexpensive, rapid, and efficient. IMPORTANCE With the emergence of drug resistance and the newly predominant serogroup O145, the control of Avian pathogenic Escherichia coli is facing a serious challenge; an efficient immunological method is urgently needed. Here, for the first time, we propose a high-throughput screening approach to search for universal protective antigens against the three traditional serogroups and the newly emerged O145. Importantly, using this approach, a total of 61 proteins regarded as probable antigens against the four important serogroups were screened, and three were shown to be immunoreactive with all antisera (covering the four serogroups), thereby providing a foundation for the development of APEC subunit vaccines against avian colibacillosis. Further, our Pan-RV pipeline will provide immunological control strategies for pathogens with complex and variable genetic backgrounds such as Escherichia coli and will make screening of bacterial vaccine candidates more inexpensive, rapid, and efficient.
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Sun J, Lin X, He Y, Zhang B, Zhou N, Huang JD. A bacterial outer membrane vesicle-based click vaccine elicits potent immune response against Staphylococcus aureus in mice. Front Immunol 2023; 14:1088501. [PMID: 36742310 PMCID: PMC9892643 DOI: 10.3389/fimmu.2023.1088501] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 01/06/2023] [Indexed: 01/20/2023] Open
Abstract
Staphylococcus aureus infection is a severe public health concern with the growing number of multidrug-resistant strains. S. aureus can circumvent the defense mechanisms of host immunity with the aid of multiple virulence factors. An efficacious multicomponent vaccine targeting diverse immune evasion strategies developed by S. aureus is thus crucial for its infection control. In this study, we exploited the SpyCatcher-SpyTag system to engineer bacterial outer membrane vesicles (OMVs) for the development of a multitargeting S. aureus click vaccine. We decorated OMVs with surface exposed SpyCatcher via a truncated OmpA(a.a 1-155)-SpyCatcher fusion. The engineered OMVs can flexibly bind with various SpyTag-fused S. aureus antigens to generate an OMV-based click vaccine. Compared with antigens mixed with alum adjuvant, the click vaccine simultaneously induced more potent antigen-specific humoral and Th1-based cellular immune response, which afforded protection against S. aureus Newman lethal challenge in a mouse model. Our study provided a flexible and versatile click vaccine strategy with the potential for fighting against emerging S. aureus clinical isolates.
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Affiliation(s)
- Jingjing Sun
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
| | - Xuansheng Lin
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Yige He
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.,School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Baozhong Zhang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Nan Zhou
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou, China
| | - Jian-Dong Huang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.,School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, Hong Kong SAR, China.,Department of Clinical Oncology, Shenzhen Key Laboratory for Cancer Metastasis and Personalized Therapy, The University of Hong Kong-Shenzhen Hospital, Shenzhen, Guangdong, China.,Guangdong-Hong Kong Joint Laboratory for RNA Medicine, Sun Yat-Sen University, Guangzhou, China
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Surface display of (R)-carbonyl reductase on Escherichia coli as biocatalyst for recycling biotransformation of 2-hydroxyacetophenone. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Principle and potential applications of the non-classical protein secretory pathway in bacteria. Appl Microbiol Biotechnol 2019; 104:953-965. [PMID: 31853566 DOI: 10.1007/s00253-019-10285-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 10/22/2019] [Accepted: 10/27/2019] [Indexed: 12/15/2022]
Abstract
In addition to the extracellular proteins secreted by known secretory pathways, a number of cytoplasmic proteins without predicable or known signal sequences or secretory motifs have been found in the extracellular milieu, and were consequently classified as non-classically secreted proteins. Non-classical protein secretion is considered to be a general, conserved cellular phenomenon in both eukaryotes and prokaryotes. There are several research hotspots on the non-classical protein secretory pathway, and the most important two of them are the recognition principle of substrate proteins and possible secretory mechanisms. To date, researchers have made some progress in understanding the characteristics of these proteins. For example, it was discovered that many non-classically secreted proteins exist and are secreted in multimeric form. Some of these proteins prefer to be clustered and exported at the poles and the septum of the cell. The majority of these proteins play different functions when they are in the intra- and extracellular environments, and several of their functions are related to survival and pathogenicity. Furthermore, non-classically secreted proteins can be used as leading proteins to guide a POI (protein of interest) out of the cells, which provides a novel strategy for protein secretion with potential applications in the industry. Summarizing these findings, this review emphasizes the hot spots related to non-classically secreted proteins in bacteria, lists the most important hypotheses on the selection and secretion mechanisms of non-classically secreted proteins, and put forward their potential applications.
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Enzymatic Synthesis of Nucleoside Triphosphates and Deoxynucleoside Triphosphates by Surface-Displayed Kinases. Appl Biochem Biotechnol 2019; 190:1271-1288. [PMID: 31745822 DOI: 10.1007/s12010-019-03138-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/12/2019] [Indexed: 02/07/2023]
Abstract
Nucleoside triphosphates and deoxynucleoside triphosphates are important biochemical molecules. In this study, recombinant Escherichia coli that could display nucleotide kinases (INP-N-NMKases) and acetate kinase (INP-N-ACKase) on the cell surface were constructed by fusing an enzyme (NMKase/ACKase) to the N-terminus of ice nucleation protein (INP-N). By using intact recombinant bacteria cells as a catalyst coupled with an ACKase-catalyzed adenosine-5'-triphosphate (ATP) regeneration system, nucleoside triphosphates (NTPs) and deoxynucleoside triphosphates (dNTPs) could be synthesized efficiently. In a reaction system with 5 mmol/l substrate, the conversion rates of cytidine-5'-triphosphate (CTP) and deoxycytidine-5'-triphosphate (dCTP) were 96% and 93%, respectively, the conversion rate of ATP and deoxyadenosine-5'-triphosphate (dATP) was 96%, the conversion rate of deoxythymidine-5'-triphosphate (dTTP) was 91%, and the conversion rate of uridine-5'-triphosphate (UTP) was 80%. There was no obvious degradation. At 37 °C, the stability of the surface-displayed fusion protein, especially in the presence of the substrate, was significantly improved. Each whole cell could be reused more than 8 times.
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Yao Y, Ding Q, Ou L. Biosynthesis of (deoxy)guanosine-5'-triphosphate by GMP kinase and acetate kinase fixed on the surface of E. coli. Enzyme Microb Technol 2018; 122:82-89. [PMID: 30638512 DOI: 10.1016/j.enzmictec.2018.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/23/2018] [Accepted: 12/19/2018] [Indexed: 11/19/2022]
Abstract
(Deoxy)guanosine-5'-triphosphate (5'-(d)GTP), the precursor for synthesizing DNA or RNA in vivo, is an important raw material for various modern biotechnologies based on PCR. In this study, we investigated the application of whole-cell catalysts constructed by bacterial cell surface display in biosynthetic reactions of 5'-(d)GTP from (deoxy)guanosine-5'-monophosphate (5'-(d)GMP). By N-terminal or N- and C-terminal fusion of the ice nucleation protein, we successfully displayed the GMP kinase of Lactobacillus bulgaricus and the acetate kinase of E. coli on the surface of E. coli cells. A large amount of soluble target protein was obtained upon induction with 0.2 mM IPTG at 25 °C for 30 h. The conversion of dGMP was up to 91% when catalysed by the surface-displayed enzymes at 37 °C for 4 h. Up to 95% of the GMP was converted after 3 h of reaction. The stability of the whole-cell catalyst at 37 °C was very good. The enzyme activity was maintained above 50% after 9 rounds of recovery. Our research showed that only one-twentieth of the initial substrate concentration of added ATP was sufficient to meet the reaction requirements.
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Affiliation(s)
- Yefeng Yao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China
| | - Qingbao Ding
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA.
| | - Ling Ou
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China.
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Engineering E. coli cell surface in order to develop a one-step purification method for recombinant proteins. AMB Express 2018; 8:107. [PMID: 29961206 PMCID: PMC6026487 DOI: 10.1186/s13568-018-0638-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Accepted: 06/25/2018] [Indexed: 12/14/2022] Open
Abstract
Sortases are enzymes mostly found in Gram-positive bacteria which cleave proteins site-specifically. This feature makes them a promising tool in molecular biology and biotechnology. In this study, using bacterial surface display of recombinant proteins and ability of sortase A in site-specifically cleavage of the amino acid sequences, a novel method for one-step purification of recombinant proteins was developed. Using computational program tools, a chimeric protein containing a metallothionein (mt) and chitin binding domain (ChBD) was attached to the C-terminal domain of the truncated outer membrane protein A (Lpp'-ompA) using sortase recognition site (amino acid residues: LPQTG) as a separator. The structure of the chimeric protein was simulated using molecular dynamics to determine if the LPQTG motif is accessible to the sortase active site. The designed chimeric protein was expressed and purified. The purified chimeric protein was also displayed on the surface of E. coli cells. Both purified chimeric protein and the E. coli cells displaying Lpp'-ompA-mt-ChBD carrier protein were then treated with sortase to evaluate the efficiency of sortase-mediated cleavage of purified chimeric protein as well as surface displayed-chimeric protein. It is shown that mt-ChBD protein was successfully cleaved and dissociated from Lpp'-ompA carrier and released into the medium after treatment with sortase in both recombinant protein and surface displayed-chimeric protein. The experimental results confirmed the molecular dynamics analysis results. The presented method could be regarded as a novel strategy for one step expression and purification of recombinant proteins.
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