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Zhang CX, Li RJ, Baude L, Reinhardt D, Xie ZP, Staehelin C. CRISPR/Cas9-Mediated Generation of Mutant Lines in Medicago truncatula Indicates a Symbiotic Role of MtLYK10 during Nodule Formation. BIOLOGY 2024; 13:53. [PMID: 38275729 PMCID: PMC10812973 DOI: 10.3390/biology13010053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/27/2024]
Abstract
CRISPR/Cas9 systems are commonly used for plant genome editing; however, the generation of homozygous mutant lines in Medicago truncatula remains challenging. Here, we present a CRISPR/Cas9-based protocol that allows the efficient generation of M. truncatula mutants. Gene editing was performed for the LysM receptor kinase gene MtLYK10 and two major facilitator superfamily transporter genes. The functionality of CRISPR/Cas9 vectors was tested in Nicotiana benthamiana leaves by editing a co-transformed GUSPlus gene. Transformed M. truncatula leaf explants were regenerated to whole plants at high efficiency (80%). An editing efficiency (frequency of mutations at a given target site) of up to 70% was reached in the regenerated plants. Plants with MtLYK10 knockout mutations were propagated, and three independent homozygous mutant lines were further characterized. No off-target mutations were identified in these lyk10 mutants. Finally, the lyk10 mutants and wild-type plants were compared with respect to the formation of root nodules induced by nitrogen-fixing Sinorhizobium meliloti bacteria. Nodule formation was considerably delayed in the three lyk10 mutant lines. Surprisingly, the size of the rare nodules in mutant plants was higher than in wild-type plants. In conclusion, the symbiotic characterization of lyk10 mutants generated with the developed CRISPR/Cas9 protocol indicated a role of MtLYK10 in nodule formation.
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Affiliation(s)
- Chun-Xiao Zhang
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Ru-Jie Li
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Laura Baude
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Didier Reinhardt
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Zhi-Ping Xie
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
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2
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Xia C, Zhao Y, Zhang L, Li X, Cheng Y, Wang D, Xu C, Qi M, Wang J, Guo X, Ye X, Huang Y, Shen D, Dou D, Cao H, Li Z, Cui Z. Myxobacteria restrain Phytophthora invasion by scavenging thiamine in soybean rhizosphere via outer membrane vesicle-secreted thiaminase I. Nat Commun 2023; 14:5646. [PMID: 37704617 PMCID: PMC10499793 DOI: 10.1038/s41467-023-41247-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 08/29/2023] [Indexed: 09/15/2023] Open
Abstract
Public metabolites such as vitamins play critical roles in maintaining the ecological functions of microbial community. However, the biochemical and physiological bases for fine-tuning of public metabolites in the microbiome remain poorly understood. Here, we examine the interactions between myxobacteria and Phytophthora sojae, an oomycete pathogen of soybean. We find that host plant and soil microbes complement P. sojae's auxotrophy for thiamine. Whereas, myxobacteria inhibits Phytophthora growth by a thiaminase I CcThi1 secreted into extracellular environment via outer membrane vesicles (OMVs). CcThi1 scavenges the required thiamine and thus arrests the thiamine sharing behavior of P. sojae from the supplier, which interferes with amino acid metabolism and expression of pathogenic effectors, probably leading to impairment of P. sojae growth and pathogenicity. Moreover, myxobacteria and CcThi1 are highly effective in regulating the thiamine levels in soil, which is correlated with the incidence of soybean Phytophthora root rot. Our findings unravel a novel ecological tactic employed by myxobacteria to maintain the interspecific equilibrium in soil microbial community.
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Affiliation(s)
- Chengyao Xia
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yuqiang Zhao
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China
| | - Lei Zhang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xu Li
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yang Cheng
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Nanjing Agriculture University, Nanjing, 210095, China
| | - Dongming Wang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Changsheng Xu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Mengyi Qi
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jihong Wang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xiangrui Guo
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xianfeng Ye
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yan Huang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Danyu Shen
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Nanjing Agriculture University, Nanjing, 210095, China
| | - Daolong Dou
- The Key Laboratory of Monitoring and Management of Plant Diseases and Insects of Ministry of Agriculture and Rural Affairs, College of Plant Protection, Nanjing Agriculture University, Nanjing, 210095, China
- Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hui Cao
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Zhoukun Li
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
| | - Zhongli Cui
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
- Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing, 210095, China.
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3
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Nydegger DT, Pujol-Giménez J, Kandasamy P, Vogt B, Hediger MA. Applications of the Microscale Thermophoresis Binding Assay in COVID-19 Research. Viruses 2023; 15:1432. [PMID: 37515120 PMCID: PMC10386446 DOI: 10.3390/v15071432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
As the COVID-19 pandemic progresses, new variants of SARS-CoV-2 continue to emerge. This underscores the need to develop optimized tools to study such variants, along with new coronaviruses that may arise in the future. Such tools will also be instrumental in the development of new antiviral drugs. Here, we introduce microscale thermophoresis (MST) as a reliable and versatile tool for coronavirus research, which we demonstrate through three different applications described in this report: (1) binding of the SARS-CoV-2 spike receptor binding domain (RBD) to peptides as a strategy to prevent virus entry, (2) binding of the RBD to the viral receptor ACE2, and (3) binding of the RBD to ACE2 in complex with the amino acid transporter SLC6A20/SIT1 or its allelic variant rs61731475 (p.Ile529Val). Our results demonstrate that MST is a highly precise approach to studying protein-protein and/or protein-ligand interactions in coronavirus research, making it an ideal tool for studying viral variants and developing antiviral agents. Moreover, as shown in our results, a unique advantage of the MST assay over other available binding assays is the ability to measure interactions with membrane proteins in their near-native plasma membrane environment.
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Affiliation(s)
- Damian T Nydegger
- Department of Nephrology and Hypertension, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
- Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
| | - Jonai Pujol-Giménez
- Department of Nephrology and Hypertension, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
- Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
| | - Palanivel Kandasamy
- Department of Nephrology and Hypertension, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
- Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
| | - Bruno Vogt
- Department of Nephrology and Hypertension, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
- Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
| | - Matthias A Hediger
- Department of Nephrology and Hypertension, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
- Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Freiburgstrasse 15, 3010 Bern, Switzerland
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4
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Lehmann EF, Liziczai M, Drożdżyk K, Altermatt P, Langini C, Manolova V, Sundstrom H, Dürrenberger F, Dutzler R, Manatschal C. Structures of ferroportin in complex with its specific inhibitor vamifeport. eLife 2023; 12:83053. [PMID: 36943194 PMCID: PMC10030120 DOI: 10.7554/elife.83053] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 02/27/2023] [Indexed: 03/18/2023] Open
Abstract
A central regulatory mechanism of iron homeostasis in humans involves ferroportin (FPN), the sole cellular iron exporter, and the peptide hormone hepcidin, which inhibits Fe2+ transport and induces internalization and degradation of FPN. Dysregulation of the FPN/hepcidin axis leads to diverse pathological conditions, and consequently, pharmacological compounds that inhibit FPN-mediated iron transport are of high clinical interest. Here, we describe the cryo-electron microscopy structures of human FPN in complex with synthetic nanobodies and vamifeport (VIT-2763), the first clinical-stage oral FPN inhibitor. Vamifeport competes with hepcidin for FPN binding and is currently in clinical development for β-thalassemia and sickle cell disease. The structures display two distinct conformations of FPN, representing outward-facing and occluded states of the transporter. The vamifeport site is located in the center of the protein, where the overlap with hepcidin interactions underlies the competitive relationship between the two molecules. The introduction of point mutations in the binding pocket of vamifeport reduces its affinity to FPN, emphasizing the relevance of the structural data. Together, our study reveals conformational rearrangements of FPN that are of potential relevance for transport, and it provides initial insight into the pharmacological targeting of this unique iron efflux transporter.
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Affiliation(s)
| | - Márton Liziczai
- Department of Biochemistry, University of Zurich, Zürich, Switzerland
| | | | | | - Cassiano Langini
- Department of Biochemistry, University of Zurich, Zürich, Switzerland
| | | | | | | | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zürich, Switzerland
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5
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Zhang Y, Li Z, Li L, Rao B, Ma L, Wang Y. A Method for Rapid Screening, Expression, and Purification of Antimicrobial Peptides. Microorganisms 2021; 9:microorganisms9091858. [PMID: 34576753 PMCID: PMC8469748 DOI: 10.3390/microorganisms9091858] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/18/2021] [Accepted: 08/22/2021] [Indexed: 11/16/2022] Open
Abstract
In this study, a method for the rapid screening, expression and purification of antimicrobial peptides (AMPs) was developed. AMP genes were fused to a heat-resistant CL7 tag using the SLOPE method, and cloned into Escherichia coli and Pichia pastoris expression vectors. Twenty E. coli and ten P. pastoris expression vectors were constructed. Expression supernatants were heated, heteroproteins were removed, and fusion proteins were purified by nickel affinity (Ni-NTA) chromatography. Fusion proteins were digested on the column using human rhinovirus (HRV) 3C protease, and AMPs were released and further purified. Five AMPs (1, 2, 6, 13, 16) were purified using the E. coli expression system, and one AMP (13) was purified using the P. pastoris expression system. Inhibition zone and minimum inhibitory concentration (MIC) tests confirmed that one P. pastoris⌐-derived and two E. coli-derived AMPs have the inhibition activity. The MIC of AMP 13 and 16 from E. coli was 24.2 μM, and the MIC of AMP 13 from P. pastoris was 8.1 μM. The combination of prokaryotic and eukaryotic expression systems expands the universality of the developed method, facilitating screening of a large number of biologically active AMPs, establishing an AMP library, and producing AMPs by industrialised biological methods.
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Affiliation(s)
- Yingli Zhang
- State Key Laboratory of Biocatalysis and Enzyme, Engineering Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, Biology Faculty of Hubei University, Hubei University, Wuhan 430062, China; (Y.Z.); (Z.L.); (L.L.); (L.M.)
| | - Zhongchen Li
- State Key Laboratory of Biocatalysis and Enzyme, Engineering Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, Biology Faculty of Hubei University, Hubei University, Wuhan 430062, China; (Y.Z.); (Z.L.); (L.L.); (L.M.)
| | - Li Li
- State Key Laboratory of Biocatalysis and Enzyme, Engineering Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, Biology Faculty of Hubei University, Hubei University, Wuhan 430062, China; (Y.Z.); (Z.L.); (L.L.); (L.M.)
| | - Ben Rao
- National Biopesticide Engineering Technology Research Center, Hubei Biopesticide Engineering Research Center, Hubei Academy of Agricultural Sciences, Biopesticide Branch of Hubei Innovation Centre of Agricultural Science and Technology, Wuhan 430064, China;
| | - Lixin Ma
- State Key Laboratory of Biocatalysis and Enzyme, Engineering Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, Biology Faculty of Hubei University, Hubei University, Wuhan 430062, China; (Y.Z.); (Z.L.); (L.L.); (L.M.)
| | - Yaping Wang
- State Key Laboratory of Biocatalysis and Enzyme, Engineering Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, Biology Faculty of Hubei University, Hubei University, Wuhan 430062, China; (Y.Z.); (Z.L.); (L.L.); (L.M.)
- Correspondence:
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6
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Chen F, Li YY, Yu YL, Dai J, Huang JL, Lin J. Simplified plasmid cloning with a universal MCS design and bacterial in vivo assembly. BMC Biotechnol 2021; 21:24. [PMID: 33722223 PMCID: PMC7962268 DOI: 10.1186/s12896-021-00679-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 02/17/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The ability to clone DNA sequences quickly and precisely into plasmids is essential for molecular biology studies. The recent development of seamless cloning technologies has made significant improvements in plasmid construction, but simple and reliable tools are always desirable for time- and labor-saving purposes. RESULTS We developed and standardized a plasmid cloning protocol based on a universal MCS (Multiple Cloning Site) design and bacterial in vivo assembly. With this method, the vector is linearized first by PCR (Polymerase Chain Reaction) or restriction digestion. Then a small amount (10 ~ 20 ng) of this linear vector can be mixed with a PCR-amplified insert (5× molar ratio against vector) and transformed directly into competent E. coli cells to obtain the desired clones through in vivo assembly. Since we used a 36-bp universal MCS as the homologous linker, any PCR-amplified insert with ~ 15 bp compatible termini can be cloned into the vector with high fidelity and efficiency. Thus, the need for redesigning insert-amplifying primers according to various vector sequences and the following PCR procedures was eliminated. CONCLUSIONS Our protocol significantly reduced hands-on time for preparing transformation reactions, had excellent reliability, and was confirmed to be a rapid and versatile plasmid cloning technique. The protocol contains mostly mixing steps, making it an extremely automation-friendly and promising tool in modern biology studies.
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Affiliation(s)
- Fan Chen
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China.
| | - Yi-Ya Li
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China
| | - Yan-Li Yu
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China
| | - Jie Dai
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China
| | - Jin-Ling Huang
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China
| | - Jie Lin
- School of Biological Science and Biotechnology, Minnan Normal University, Zhangzhou, 363000, P.R. China
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7
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Ren F, Swevers L, Lu Q, Zhao Y, Yan J, Li H, Sun J. Effect of mutations in capsid shell protein on the assembly of BmCPV virus-like particles. J Gen Virol 2020; 102. [PMID: 33331809 DOI: 10.1099/jgv.0.001542] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is a typical single-layer capsid dsRNA virus belonging to the genus Cypovirus in the family Reoviridae. The results of cryo-electron microscopy showed that the BmCPV capsid consists of 60 asymmetric units, and each asymmetric unit contains one turret protein (TP), two large protrusion proteins (LPP) and two capsid shell proteins (CSP). CSP has the ability to self-assemble into virus-like particles (VLPs), and the small protrusion domain (SPD) in CSP may play an essential role in the assembly of viral capsids. In this study, three critical amino acid sites, D828, S829 and V945, in the SPD were efficiently mutated (point mutation) based on the principle of PCR circular mutagenesis. Moreover, a multi-gene expression system, Ac-MultiBac baculovirus, was used to produce eight different recombinant VLPs in vitro. Transmission electron microscopy showed that the single site and double site mutations had little effect on the efficiency and morphology of the assembly of VLPs. Still, the simultaneous mutation of the three sites had a significant impact. The experimental results demonstrate that the SPD of CSP plays an essential role in assembly of the viral capsid, which lays the foundation for further analysis of the molecular and structural mechanism of BmCPV capsid assembly.
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Affiliation(s)
- Feifei Ren
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Aghia Paraskevi, Athens, Greece.,Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Luc Swevers
- Insect Molecular Genetics and Biotechnology, Institute of Biosciences and Applications, National Centre for Scientific Research Demokritos, Aghia Paraskevi, Athens, Greece
| | - Qiuyuan Lu
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Yongchao Zhao
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Jiming Yan
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Haiyun Li
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
| | - Jingchen Sun
- Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou 510642, PR China
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8
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Tao CC, Yang Y, Li F, Qiao L, Wu Y, Sun XD, Zhang YY, Li CL. Cloning short DNA into plasmids by one-step PCR. Thorac Cancer 2020; 11:3409-3415. [PMID: 33015950 PMCID: PMC7605993 DOI: 10.1111/1759-7714.13660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/30/2020] [Accepted: 08/30/2020] [Indexed: 11/30/2022] Open
Abstract
Background Plasmid construction of small fragments of interest (such as insertion of small fragment marker genes, expression of shRNA, siRNA, etc) is the basis of many biomolecular experiments. Here, we describe a method to clone short DNA into vectors by polymerase chain reaction (PCR), named one‐step PCR cloning. Our method uses PCR to amplify the entire circular plasmid. The PCR was performed by the primers containing the gene of short DNA with overlapping sequences between 10–15 bp. The PCR products were then transformed into E. coli and cyclized by homologous recombination in vivo. Methods The pEGFP‐N1‐HA plasmid was constructed by one‐step PCR and transformation. Cells were transfected with pEGFP‐N1‐HA and pEGFP‐N1 plasmid using TurboFect transfection reagent. Protein expression was detected by western blotting and the HA‐GFP fusion protein was detected by confocal microscopy. Results The pEGFP‐N1‐HA plasmid was successfully constructed and HA expression in cells. Conclusions Free from the limitations of restriction enzyme sites and omitting the ligation process, our method offers a flexible and economical option of plasmid construction. Key points
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Affiliation(s)
- Cheng-Cheng Tao
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
| | - Ying Yang
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
| | - Fang Li
- Department of Medical Oncology, Sichuan Cancer Hospital and Institute, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Ling Qiao
- School of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Yue Wu
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
| | - Xiao-Dong Sun
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
| | - Yuan-Yuan Zhang
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China.,School of Biological Sciences and Technology, Chengdu Medical College, Chengdu, China
| | - Chang-Long Li
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
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9
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Manatschal C, Pujol-Giménez J, Poirier M, Reymond JL, Hediger MA, Dutzler R. Mechanistic basis of the inhibition of SLC11/NRAMP-mediated metal ion transport by bis-isothiourea substituted compounds. eLife 2019; 8:51913. [PMID: 31804182 PMCID: PMC6917499 DOI: 10.7554/elife.51913] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/22/2019] [Indexed: 12/23/2022] Open
Abstract
In humans, the divalent metal ion transporter-1 (DMT1) mediates the transport of ferrous iron across the apical membrane of enterocytes. Hence, its inhibition could be beneficial for the treatment of iron overload disorders. Here we characterize the interaction of aromatic bis-isothiourea-substituted compounds with human DMT1 and its prokaryotic homologue EcoDMT. Both transporters are inhibited by a common competitive mechanism with potencies in the low micromolar range. The crystal structure of EcoDMT in complex with a brominated derivative defines the binding of the inhibitor to an extracellular pocket of the transporter in direct contact with residues of the metal ion coordination site, thereby interfering with substrate loading and locking the transporter in its outward-facing state. Mutagenesis and structure-activity relationships further support the observed interaction mode and reveal species-dependent differences between pro- and eukaryotic transporters. Together, our data provide the first detailed mechanistic insight into the pharmacology of SLC11/NRAMP transporters.
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Affiliation(s)
| | - Jonai Pujol-Giménez
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.,Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, Inselspital, University of Bern, Bern, Switzerland.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Marion Poirier
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.,Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, Inselspital, University of Bern, Bern, Switzerland.,Department of Biomedical Research, University of Bern, Bern, Switzerland
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
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10
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Krebs AS, Bierig T, Collu G, Benoit RM. Seamless insert-plasmid assembly at sub-terminal homologous sequences. Plasmid 2019; 106:102445. [PMID: 31669339 DOI: 10.1016/j.plasmid.2019.102445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 10/25/2022]
Abstract
The engineering of fusion proteins for structural biology and protein nanotechnology often requires seamless DNA assembly with slight variations in the domain boundaries. To improve the molecular biology workflow for such projects, we evaluated the use of sub-terminal homologous sequences (HS) for co-transformation cloning and for T5 exonuclease / Phusion DNA polymerase mediated in vitro assembly. To quantify the effects of different HS-to-ends distances on cloning efficiency, we designed a blue-white-pink screening system that allowed us to easily identify positive clones (blue colonies), negative clones resulting from circular template plasmid (pink colonies) and negative colonies originating from linearized plasmids that have recircularized without an insert (white colonies). Our experiments show that both methods are feasible with HS-to-ends distances up to at least 10 base pairs. Using a combination of co-transformation cloning at sub-terminal HS and nucleotide insertions in non-annealing primer 5'-overhangs, we integrated a fusion protein into the third intracellular loop (ICL) of a G-protein-coupled receptor (GPCR) with nine different linker boundaries, using only a single plasmid linearization reaction. This molecular cloning approach is an invaluable tool for protein engineering, protein nanotechnology and synthetic biology that extends the range of applications of DNA assembly strategies.
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Affiliation(s)
- Anna-Sophia Krebs
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Tobias Bierig
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Gabriella Collu
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland; Department of Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Roger M Benoit
- Laboratory of Nanoscale Biology, Division of Biology and Chemistry, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
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11
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Watson JF, García-Nafría J. In vivo DNA assembly using common laboratory bacteria: A re-emerging tool to simplify molecular cloning. J Biol Chem 2019; 294:15271-15281. [PMID: 31522138 DOI: 10.1074/jbc.rev119.009109] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular cloning is a cornerstone of biomedical, biotechnological, and synthetic biology research. As such, improved cloning methodologies can significantly advance the speed and cost of research projects. Whereas current popular cloning approaches use in vitro assembly of DNA fragments, in vivo cloning offers potential for greater simplification. It is generally assumed that bacterial in vivo cloning requires Escherichia coli strains with enhanced recombination ability; however, this is incorrect. A widely present, bacterial RecA-independent recombination pathway is re-emerging as a powerful tool for molecular cloning and DNA assembly. This poorly understood pathway offers optimal cloning properties (i.e. seamless, directional, and sequence-independent) without requiring in vitro DNA assembly or specialized bacteria, therefore vastly simplifying cloning procedures. Although the use of this pathway to perform DNA assembly was first reported over 25 years ago, it failed to gain popularity, possibly due to both technical and circumstantial reasons. Technical limitations have now been overcome, and recent reports have demonstrated its versatility for DNA manipulation. Here, we summarize the historical trajectory of this approach and collate recent reports to provide a roadmap for its optimal use. Given the simplified protocols and minimal requirements, cloning using in vivo DNA assembly in E. coli has the potential to become widely employed across the molecular biology community.
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Affiliation(s)
- Jake F Watson
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Javier García-Nafría
- Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, BIFI-IQFR (CSIC), 50018 Zaragoza, Spain
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12
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Zeng F, Zhang S, Hao Z, Duan S, Meng Y, Li P, Dong J, Lin Y. Efficient strategy for introducing large and multiple changes in plasmid DNA. Sci Rep 2018; 8:1714. [PMID: 29379085 PMCID: PMC5789069 DOI: 10.1038/s41598-018-20169-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 01/15/2018] [Indexed: 12/15/2022] Open
Abstract
While the QuikChange site-directed mutagenesis method and its later modifications are extremely useful and simple, they suffer from several drawbacks. Here, we propose a new method, named LFEAP mutagenesis (Ligation of Fragment Ends After PCR) for creating various mutations in plasmid by leveraging three existing concepts: inverse PCR, single primer PCR, and sticky-end assembly. The first inverse PCR on the target plasmid yielded linearized DNA fragments with mutagenic ends, and a second single primer PCR resulted in complementary single-stranded DNA fragments with the addition of overhangs at the 5' end of each strand. The resulting single strands were then annealed to produce double-stranded DNA with free 5' single-stranded DNA tails. These products with compatible sticky ends were efficiently assembled into a circular, mutagenized plasmid. With this strategy, multiple simultaneous changes (up to 15) and mutations in large plasmids (up to 50 kb) were achieved with high efficiency and fidelity. LFEAP mutagenesis is a versatile method that offers significant advantages for introducing large and multiple changes in plasmid DNA.
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Affiliation(s)
- Fanli Zeng
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China
| | - Suhua Zhang
- Institute of Biophysics, Hebei University of Technology, Tianjin, 300401, China
| | - Zhimin Hao
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China
| | - Shixin Duan
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China
| | - Yanan Meng
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China
| | - Pan Li
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China
| | - Jingao Dong
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, China.
| | - Yibin Lin
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston McGovern Medical School, 6431 Fannin Street, Houston, TX, 77030, USA.
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13
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Gentile DR, Rathinaswamy MK, Jenkins ML, Moss SM, Siempelkamp BD, Renslo AR, Burke JE, Shokat KM. Ras Binder Induces a Modified Switch-II Pocket in GTP and GDP States. Cell Chem Biol 2017; 24:1455-1466.e14. [PMID: 29033317 PMCID: PMC5915340 DOI: 10.1016/j.chembiol.2017.08.025] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 07/31/2017] [Accepted: 08/30/2017] [Indexed: 12/31/2022]
Abstract
Covalent inhibitors of K-Ras(G12C) have been reported that exclusively recognize the GDP state. Here, we utilize disulfide tethering of a non-natural cysteine (K-Ras(M72C)) to identify a new switch-II pocket (S-IIP) binding ligand (2C07) that engages the active GTP state. Co-crystal structures of 2C07 bound to H-Ras(M72C) reveal binding in a cryptic groove we term S-IIG. In the GppNHp state, 2C07 binding to a modified S-IIP pushes switch I away from the nucleotide, breaking the network of polar contacts essential for adopting the canonical GTP state. Biochemical studies show that 2C07 alters nucleotide preference and inhibits SOS binding and catalyzed nucleotide exchange. 2C07 was converted to irreversible covalent analogs, which target both nucleotide states, inhibit PI3K activation in vitro, and function as occupancy probes to detect reversible engagement in competition assays. Targeting both nucleotide states opens the possibility of inhibiting oncogenic mutants of Ras, which exist predominantly in the GTP state in cells.
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Affiliation(s)
- Daniel R Gentile
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - Manoj K Rathinaswamy
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Steven M Moss
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA
| | - Braden D Siempelkamp
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Adam R Renslo
- Small Molecule Discovery Center and Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada.
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA.
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14
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Unprecedented pathway of reducing equivalents in a diflavin-linked disulfide oxidoreductase. Proc Natl Acad Sci U S A 2017; 114:12725-12730. [PMID: 29133410 DOI: 10.1073/pnas.1713698114] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Flavoproteins participate in a wide variety of physiologically relevant processes that typically involve redox reactions. Within this protein superfamily, there exists a group that is able to transfer reducing equivalents from FAD to a redox-active disulfide bridge, which further reduces disulfide bridges in target proteins to regulate their structure and function. We have identified a previously undescribed type of flavin enzyme that is exclusive to oxygenic photosynthetic prokaryotes and that is based on the primary sequence that had been assigned as an NADPH-dependent thioredoxin reductase (NTR). However, our experimental data show that the protein does not transfer reducing equivalents from flavins to disulfides as in NTRs but functions in the opposite direction. High-resolution structures of the protein from Gloeobacter violaceus and Synechocystis sp. PCC6803 obtained by X-ray crystallography showed two juxtaposed FAD molecules per monomer in redox communication with an active disulfide bridge in a variant of the fold adopted by NTRs. We have tentatively named the flavoprotein "DDOR" (diflavin-linked disulfide oxidoreductase) and propose that its activity is linked to a thiol-based transfer of reducing equivalents in bacterial membranes. These findings expand the structural and mechanistic repertoire of flavoenzymes with oxidoreductase activity and pave the way to explore new protein engineering approaches aimed at designing redox-active proteins for diverse biotechnological applications.
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15
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Xu JZ, Zhang WG. Strategies used for genetically modifying bacterial genome: site-directed mutagenesis, gene inactivation, and gene over-expression. J Zhejiang Univ Sci B 2016; 17:83-99. [PMID: 26834010 DOI: 10.1631/jzus.b1500187] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
With the availability of the whole genome sequence of Escherichia coli or Corynebacterium glutamicum, strategies for directed DNA manipulation have developed rapidly. DNA manipulation plays an important role in understanding the function of genes and in constructing novel engineering bacteria according to requirement. DNA manipulation involves modifying the autologous genes and expressing the heterogenous genes. Two alternative approaches, using electroporation linear DNA or recombinant suicide plasmid, allow a wide variety of DNA manipulation. However, the over-expression of the desired gene is generally executed via plasmid-mediation. The current review summarizes the common strategies used for genetically modifying E. coli and C. glutamicum genomes, and discusses the technical problem of multi-layered DNA manipulation. Strategies for gene over-expression via integrating into genome are proposed. This review is intended to be an accessible introduction to DNA manipulation within the bacterial genome for novices and a source of the latest experimental information for experienced investigators.
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Affiliation(s)
- Jian-zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Wei-guo Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
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16
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The BR domain of PsrP interacts with extracellular DNA to promote bacterial aggregation; structural insights into pneumococcal biofilm formation. Sci Rep 2016; 6:32371. [PMID: 27582320 PMCID: PMC5007671 DOI: 10.1038/srep32371] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/05/2016] [Indexed: 12/21/2022] Open
Abstract
The major human pathogen Streptococcus pneumoniae is a leading cause of disease and death worldwide. Pneumococcal biofilm formation within the nasopharynx leads to long-term colonization and persistence within the host. We have previously demonstrated that the capsular surface-associated pneumococcal serine rich repeat protein (PsrP), key factor for biofilm formation, binds to keratin-10 (KRT10) through its microbial surface component recognizing adhesive matrix molecule (MSCRAMM)-related globular binding region domain (BR187–385). Here, we show that BR187–385 also binds to DNA, as demonstrated by electrophoretic mobility shift assays and size exclusion chromatography. Further, heterologous expression of BR187–378 or the longer BR120–378 construct on the surface of a Gram-positive model host bacterium resulted in the formation of cellular aggregates that was significantly enhanced in the presence of DNA. Crystal structure analyses revealed the formation of BR187–385 homo-dimers via an intermolecular β-sheet, resulting in a positively charged concave surface, shaped to accommodate the acidic helical DNA structure. Furthermore, small angle X-ray scattering and circular dichroism studies indicate that the aggregate-enhancing N-terminal region of BR120–166 adopts an extended, non-globular structure. Altogether, our results suggest that PsrP adheres to extracellular DNA in the biofilm matrix and thus promotes pneumococcal biofilm formation.
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17
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Venetz D, Koovely D, Weder B, Neri D. Targeted Reconstitution of Cytokine Activity upon Antigen Binding using Split Cytokine Antibody Fusion Proteins. J Biol Chem 2016; 291:18139-47. [PMID: 27402834 PMCID: PMC5000063 DOI: 10.1074/jbc.m116.737734] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 06/28/2016] [Indexed: 01/05/2023] Open
Abstract
The targeted assembly of antibody products upon antigen binding represents a novel strategy for the reconstitution of potent therapeutic activity at the site of disease, sparing healthy tissues. We demonstrate that interleukin-12, a heterodimeric pro-inflammatory cytokine consisting of the disulfide-linked p40 and p35 subunits, can be reconstituted by sequential reassembly of fusion proteins based on antibody fragments and interleukin-12 subunit mutants. Analysis of the immunostimulatory properties of interleukin-12 and its derivatives surprisingly revealed that the mutated p35 subunit partially retained the activity of the parental cytokine, whereas the p40 subunit alone was not able to stimulate T cells or natural killer cells. The concept of stepwise antibody-based reassembly of split cytokines could be useful for the development of other anticancer therapeutics with improved safety and tolerability.
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Affiliation(s)
- Dario Venetz
- From the Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zürich), Vladimir-Prelog-Weg 1-5/10, CH-8093 Zürich, Switzerland
| | - Danil Koovely
- From the Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zürich), Vladimir-Prelog-Weg 1-5/10, CH-8093 Zürich, Switzerland
| | - Bruce Weder
- From the Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zürich), Vladimir-Prelog-Weg 1-5/10, CH-8093 Zürich, Switzerland
| | - Dario Neri
- From the Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology (ETH Zürich), Vladimir-Prelog-Weg 1-5/10, CH-8093 Zürich, Switzerland
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18
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Zhang P, Miao D, Zhang Y, Wang M, Hu Z, Lü P, Yao Q. Cloning and rescue of the genome of Bombyx mori bidensovirus, and characterization of a recombinant virus. Virol J 2016; 13:126. [PMID: 27391602 PMCID: PMC4938981 DOI: 10.1186/s12985-016-0576-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/28/2016] [Indexed: 01/12/2023] Open
Abstract
Background Bombyx mori bidensovirus (BmBDV), which belongs to the Bidnaviridae family established by the International Committee on Taxonomy of Viruses in 2011, was the first bidensovirus identified in insects. The structure of BmBDV is similar to that of parvoviruses, while its replication is similar to that of adenoviruses. Although BmBDV has the potential to be used as a tool in biological pest control and as an expression vector, virus rescue has been a bottleneck in the application of this virus. Methods In this study, we constructed a full-length genomic clone of BmBDV and showed that its terminal structure was restored. A recombinant BmBDV that expressed the green fluorescence protein (GFP) gene was constructed. Then, BmN cells, which are an ovarian cell line, were co-transfected with the linearized genome using continuous culture and expanded cell culture methods. Results The results showed that the GFP gene was expressed successfully, and that cell lesions occurred in virus-infected cells. Furthermore, typical densonucleosis viruses were observed in reinfected silkworm larvae and larval midgut tissues infected by BmBDV, as evidenced by the emission of green fluorescence. Conclusions Overall, these results suggest that the virus could be rescued from the infected BmN cells after co-transfection with the linear full length virus genome.
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Affiliation(s)
- Panpan Zhang
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Di Miao
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Yahui Zhang
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Meizi Wang
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Zhaoyang Hu
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Peng Lü
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Qin Yao
- Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China.
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19
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An auto-inducible expression system based on the RhlI-RhlR quorum-sensing regulon for recombinant protein production in E. coli. BIOTECHNOL BIOPROC E 2016. [DOI: 10.1007/s12257-015-0507-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Abstract
Secretory azoospermia is a severe form of male infertility caused by unknown factors. DAX-1 is predominantly expressed in mammalian reproductive tissues and plays an important role in spermatogenesis because Dax-1 knockout male mice show spermatogenesis defects. To examine whether DAX-1 is involved in the pathogenesis of secretory azoospermia in humans, we sequenced all of the exons of DAX-1 in 776 patients diagnosed with secretory azoospermia and 709 proven fertile men. A number of coding mutations unique to the patient group, including two synonymous mutations and six missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that the V385L mutation caused the reduced functioning of DAX-1. This novel mutation (p. V385L) of DAX-1 is the first to be identified in association with secretory azoospermia, thereby highlighting the important role of DAX-1 in spermatogenesis.
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Affiliation(s)
- Lisha Mou
- Shenzhen Key Laboratory of Genitourinary Tumor, Shenzhen Domesticated Organ Medical Engineering Research and Development Center, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Institute of Urology, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen PKU-HKUST Medical Center, Shenzhen, 518036, China
| | - Nie Xie
- Shenzhen Key Laboratory of Genitourinary Tumor, Shenzhen Domesticated Organ Medical Engineering Research and Development Center, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Institute of Urology, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen PKU-HKUST Medical Center, Shenzhen, 518036, China
| | - Lihua Yang
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Institute of Urology, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen PKU-HKUST Medical Center, Shenzhen, 518036, China
| | - Yuchen Liu
- Shenzhen Key Laboratory of Genitourinary Tumor, Shenzhen Domesticated Organ Medical Engineering Research and Development Center, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
| | - Ruiying Diao
- Shenzhen Key Laboratory of Genitourinary Tumor, Shenzhen Domesticated Organ Medical Engineering Research and Development Center, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
| | - Zhiming Cai
- Shenzhen Key Laboratory of Genitourinary Tumor, Shenzhen Domesticated Organ Medical Engineering Research and Development Center, Shenzhen Second People's Hospital, First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China
| | - Honggang Li
- The Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- * E-mail: (YG); (HL)
| | - Yaoting Gui
- Guangdong and Shenzhen Key Laboratory of Male Reproductive Medicine and Genetics, Institute of Urology, Peking University Shenzhen Hospital, Biomedical Research Institute, Shenzhen PKU-HKUST Medical Center, Shenzhen, 518036, China
- * E-mail: (YG); (HL)
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21
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The Staphylococcus aureus protein-coding gene gdpS modulates sarS expression via mRNA-mRNA interaction. Infect Immun 2015; 83:3302-10. [PMID: 26056387 DOI: 10.1128/iai.00159-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 05/29/2015] [Indexed: 12/18/2022] Open
Abstract
Staphylococcus aureus is an important Gram-positive pathogen responsible for numerous diseases ranging from localized skin infections to life-threatening systemic infections. The virulence of S. aureus is essentially determined by a wide spectrum of factors, including cell wall-associated proteins and secreted toxins that are precisely controlled in response to environmental changes. GGDEF domain protein from Staphylococcus (GdpS) is the only conserved staphylococcal GGDEF domain protein that is involved not in c-di-GMP synthesis but in the virulence regulation of S. aureus NCTC8325. Our previous study showed that the inactivation of gdpS generates an extensive change of virulence factors together with, in particular, a major Spa (protein A) surface protein. As reported, sarS is a direct positive regulator of spa. The decreased transcript levels of sarS in the gdpS mutant compared with the parental NCTC8325 strain suggest that gdpS affects spa through interaction with sarS. In this study, site mutation and complementary experiments showed that the translation product of gdpS was not involved in the regulation of transcript levels of sarS. We found that gdpS functioned through direct RNA-RNA base pairing with the 5' untranslated region (5'UTR) of sarS mRNA and that a putative 18-nucleotide region played a significant role in the regulatory process. Furthermore, the mRNA half-life analysis of sarS in the gdpS mutant showed that gdpS positively regulates the mRNA levels of sarS by contributing to the stabilization of sarS mRNA, suggesting that gdpS mRNA may regulate spa expression in an RNA-dependent pathway.
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22
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Xia Y, Chu W, Qi Q, Xun L. New insights into the QuikChange™ process guide the use of Phusion DNA polymerase for site-directed mutagenesis. Nucleic Acids Res 2014; 43:e12. [PMID: 25399421 PMCID: PMC4333370 DOI: 10.1093/nar/gku1189] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The QuikChange™ site-directed mutagenesis method is popular but imperfect. An improvement by using partially overlapping primers has been reported several times; however, it is incompatible with the proposed mechanism. The QuikChange™ method using complementary primers is proposed to linearly amplify a target plasmid with the products annealing to produce double-stranded DNA molecules with 5'-overhangs. The overhang annealing is supposed to form circular plasmids with staggered breaks, which can be repaired in Escherichia coli after transformation. Here, we demonstrated that the PCR enzyme fills the 5'-overhangs in the early cycles, and the product is then used as the template for exponential amplification. The linear DNA molecules with homologous ends are joined to generate the plasmid with the desired mutations through homologous recombination in E. coli. The correct understanding is important to method improvements, guiding us to use partially overlapping primers and Phusion DNA polymerase for site-directed mutagenesis. Phusion did not amplify a plasmid with complementary primers but used partially overlapping primers to amplify the plasmid, producing linear DNA molecules with homologous ends for site-directed mutagenesis.
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Affiliation(s)
- Yongzhen Xia
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, P. R. China
| | - Wenqiao Chu
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, P. R. China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, P. R. China
| | - Luying Xun
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, P. R. China School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520, USA
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23
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Bu Y, Wang H, Li J, Zhang Z, Hu Y, Xu Z. Long distance multiple-site directed plasmid mutagenesis by one-step PCR using non-overlapped primers. Mol Biotechnol 2014; 55:49-53. [PMID: 23644994 DOI: 10.1007/s12033-013-9665-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Site-directed mutagenesis is a very important technique in molecular biological researches. We have developed a new method for long distance multiple-site plasmid mutation by one-step PCR using non-overlap primers. These primers were carefully designed and contained desired mutations in the middle of the primers flanked with 18-25 bp of correct sequence. One pair of the primers was able to generate a short megaprimer. Decreases in the concentrations of these primers increased efficiency of the multiple-site plasmid mutation. All of the mutant PCRs were performed at a common annealing temperature at 55 °C. This method could be widely used in all multiple-site plasmid mutations.
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Affiliation(s)
- Yuling Bu
- Key Laboratory of Brain Functional Genomics, Ministry of Education, Shanghai Key Laboratory of Brain Functional Genomics, East China Normal University, Shanghai, 200062, People's Republic of China
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Schulte T, Löfling J, Mikaelsson C, Kikhney A, Hentrich K, Diamante A, Ebel C, Normark S, Svergun D, Henriques-Normark B, Achour A. The basic keratin 10-binding domain of the virulence-associated pneumococcal serine-rich protein PsrP adopts a novel MSCRAMM fold. Open Biol 2014; 4:130090. [PMID: 24430336 PMCID: PMC3909270 DOI: 10.1098/rsob.130090] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Streptococcus pneumoniae is a major human pathogen, and a leading cause of disease and death worldwide. Pneumococcal invasive disease is triggered by initial asymptomatic colonization of the human upper respiratory tract. The pneumococcal serine-rich repeat protein (PsrP) is a lung-specific virulence factor whose functional binding region (BR) binds to keratin-10 (KRT10) and promotes pneumococcal biofilm formation through self-oligomerization. We present the crystal structure of the KRT10-binding domain of PsrP (BR187–385) determined to 2.0 Å resolution. BR187–385 adopts a novel variant of the DEv-IgG fold, typical for microbial surface components recognizing adhesive matrix molecules adhesins, despite very low sequence identity. An extended β-sheet on one side of the compressed, two-sided barrel presents a basic groove that possibly binds to the acidic helical rod domain of KRT10. Our study also demonstrates the importance of the other side of the barrel, formed by extensive well-ordered loops and stabilized by short β-strands, for interaction with KRT10.
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Affiliation(s)
- Tim Schulte
- Science for Life Laboratory, Center for Infectious Medicine (CIM), Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet Science Park, Tomtebodavägen 23A Solna, Stockholm 17165, Sweden
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Mou L, Zhang Q, Wang Y, Zhang Q, Sun L, Li C, Huang W, Yuan Y, Duan Y, Diao R, Jiang Z, Ye J, Cai Z, Gui Y. Identification of Ube2b as a Novel Target of Androgen Receptor in Mouse Sertoli Cells1. Biol Reprod 2013; 89:32. [DOI: 10.1095/biolreprod.112.103648] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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26
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Liu Y, Wu T, Song J, Chen X, Zhang Y, Wan Y. A mutant screening method by critical annealing temperature-PCR for site-directed mutagenesis. BMC Biotechnol 2013; 13:21. [PMID: 23497028 PMCID: PMC3606131 DOI: 10.1186/1472-6750-13-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 02/19/2013] [Indexed: 11/24/2022] Open
Abstract
Background Distinguishing desired mutants from parental templates and undesired mutants is a problem not well solved in Quikchange™ mutagenesis. Although Dpn I digestion can eliminate methylated parental (WT) DNA, the efficiency is not satisfying due to the existence of hemi-methylated DNA in the PCR products, which is resistant to Dpn I. The present study designed a novel critical annealing temperature (Tc)-PCR to replace Dpn I digestion for more perfect mutant distinguishing, in which part-overlapping primers containing mutation(s) were used to reduce initial concentration of template DNA in mutagenic PCR. A Tc-PCR with the same mutagenic primers was performed without Dpn I digestion. The Tc for each pair of the primers was identified by gradient PCR. The relationship between PCR-identified Tc and Tm of the primers was analyzed and modeled with correlation and regression. Results Gradient PCR identified a Tc for each of 14 tested mutagenic primers, which could discriminate mismatched parental molecules and undesired mutants from desired mutants. The PCR-identified Tc was correlated to the primer’s Tm (r = 0.804, P<0.0001). Thus, in practical applications, the Tc can be easily calculated with a regression equation, Tc = 48.81 + 0.253*Tm. Conclusions The new protocol introduced a novel Tc-PCR method for mutant screening which can more efficiently and accurately select against parental molecules and undesired mutations in mutagenic sequence segments.
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Affiliation(s)
- Ying Liu
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Hubei, 430071, People's Republic of China
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Wu D, Guo X, Lu J, Sun X, Li F, Chen Y, Xiao D. A rapid and efficient one-step site-directed deletion, insertion, and substitution mutagenesis protocol. Anal Biochem 2012; 434:254-8. [PMID: 23256925 DOI: 10.1016/j.ab.2012.11.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 11/09/2012] [Accepted: 11/20/2012] [Indexed: 12/21/2022]
Abstract
A rapid and efficient site-directed mutagenesis (SDM) protocol based on two separate polymerase chain reaction (PCR) amplifications and homologous recombination in Escherichia coli is described. This protocol can introduce deletions, substitutions, and insertions into any amplifiable site of the target genes by ligating two amplified DNA fragments into vectors. Compared with previously reported PCR-based SDM methods, our protocol significantly prevents primer dimerization even though partially complementary primers were used for PCR. The genome with the target gene was used directly as template, and DpnI was unnecessary. All of the procedures were performed within 24 h. The mutation frequencies of deletion, substitution, and insertion of the PEP4 (encode proteinase A) gene of Saccharomyces cerevisiae were nearly 100% using this new method. Thus, this method can potentially facilitate high-throughput genetic engineering and structure-function analyses and is useful for molecular biological research.
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Affiliation(s)
- Deguang Wu
- Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China
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Loop-mediated isothermal amplification for rapid and convenient detection of Mycoplasma hyopneumoniae. World J Microbiol Biotechnol 2012. [PMID: 23184577 DOI: 10.1007/s11274-012-1216-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Loop-mediated isothermal amplification (LAMP), a novel method of gene amplification, was employed in this study for detecting Mycoplasma hyopneumoniae in the respiratory tract or lungs of swine. The pathogen can be detected in LAMP reactions containing as few as 10 fg purified target DNA (10 copies of M. hyopneumoniae genome) within 30 min, which was comparable to real-time PCR. After 30-min reaction at 63 °C, the addition of a certain amount of dye (SYBR Green I and hydroxyl naphthol blue at a proper ratio) into the LAMP reaction system makes the results easily determined as positive or negative by visual inspection. In addition, the LAMP was able to distinguish between M. hyopneumoniae and other closely-related mycoplasma strains, indicating a high degree of specificity. The LAMP assay was more simple and cheap, since the reaction could be completed under isothermal conditions and less laboratorial infrastructure are required. And, it was proven reliable for M. hyopneumoniae diagnosis of nasal swab and lung samples from the field.
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Abstract
N-linked glycosylation is a critical determinant of protein structure and function, regulating processes such as protein folding, stability and localization, ligand–receptor binding and intracellular signalling. TβRII [type II TGF-β (transforming growth factor β) receptor] plays a crucial role in the TGF-β signalling pathway. Although N-linked glycosylation of TβRII was first demonstrated over a decade ago, it was unclear how this modification influenced TβRII biology. In the present study, we show that inhibiting the N-linked glycosylation process successfully hinders binding of TGF-β1 to TβRII and subsequently renders cells resistant to TGF-β signalling. The lung cancer cell line A549, the gastric carcinoma cell line MKN1 and the immortal cell line HEK (human embryonic kidney)-293 exhibit reduced TGF-β signalling when either treated with two inhibitors, including tunicamycin (a potent N-linked glycosylation inhibitor) and kifunensine [an inhibitor of ER (endoplasmic reticulum) and Golgi mannosidase I family members], or introduced with a non-glycosylated mutant version of TβRII. We demonstrate that defective N-linked glycosylation prevents TβRII proteins from being transported to the cell surface. Moreover, we clearly show that not only the complex type, but also a high-mannose type, of TβRII can be localized on the cell surface. Collectively, these findings demonstrate that N-linked glycosylation is essentially required for the successful cell surface transportation of TβRII, suggesting a novel mechanism by which the TGF-β sensitivity can be regulated by N-linked glycosylation levels of TβRII.
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Munteanu B, Braun M, Boonrod K. Improvement of PCR reaction conditions for site-directed mutagenesis of big plasmids. J Zhejiang Univ Sci B 2012; 13:244-7. [PMID: 22467364 DOI: 10.1631/jzus.b1100180] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
QuickChange mutagenesis is the method of choice for site-directed mutagenesis (SDM) of target sequences in a plasmid. It can be applied successfully to small plasmids (up to 10 kb). However, this method cannot efficiently mutate bigger plasmids. Using KOD Hot Start polymerase in combination with high performance liquid chromatography (HPLC) purified primers, we were able to achieve SDM in big plasmids (up to 16 kb) involving not only a single base change but also multiple base changes. Moreover, only six polymerase chain reaction (PCR) cycles and 0.5 µl of polymerase (instead of 18 PCR cycles and 1.0 µl of enzyme in the standard protocol) were sufficient for the reaction.
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Affiliation(s)
- Bogdan Munteanu
- RLP AgroScience GmbH, AlPlanta-Institute for Plant Research, Breitenweg 71, D-67435 Neustadt, Germany
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Bi Y, Qiao X, Hua Z, Zhang L, Liu X, Li L, Hua W, Xiao H, Zhou J, Wei Q, Zheng X. An asymmetric PCR-based, reliable and rapid single-tube native DNA engineering strategy. BMC Biotechnol 2012; 12:39. [PMID: 22768962 PMCID: PMC3408372 DOI: 10.1186/1472-6750-12-39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 07/06/2012] [Indexed: 12/24/2022] Open
Abstract
Background Widely used restriction-dependent cloning methods are labour-intensive and time-consuming, while several types of ligase-independent cloning approaches have inherent limitations. A rapid and reliable method of cloning native DNA sequences into desired plasmids are highly desired. Results This paper introduces ABI-REC, a novel strategy combining asymmetric bridge PCR with intramolecular homologous recombination in bacteria for native DNA cloning. ABI-REC was developed to precisely clone inserts into defined location in a directional manner within recipient plasmids. It featured an asymmetric 3-primer PCR performed in a single tube that could robustly amplify a chimeric insert-plasmid DNA sequence with homologous arms at both ends. Intramolecular homologous recombination occurred to the chimera when it was transformed into E.coli and produced the desired recombinant plasmids with high efficiency and fidelity. It is rapid, and does not involve any operational nucleotides. We proved the reliability of ABI-REC using a double-resistance reporter assay, and investigated the effects of homology and insert length upon its efficiency. We found that 15 bp homology was sufficient to initiate recombination, while 25 bp homology had the highest cloning efficiency. Inserts up to 4 kb in size could be cloned by this method. The utility and advantages of ABI-REC were demonstrated through a series of pig myostatin (MSTN) promoter and terminator reporter plasmids, whose transcriptional activity was assessed in mammalian cells. We finally used ABI-REC to construct a pig MSTN promoter-terminator cassette reporter and showed that it could work coordinately to express EGFP. Conclusions ABI-REC has the following advantages: (i) rapid and highly efficient; (ii) native DNA cloning without introduction of extra bases; (iii) restriction-free; (iv) easy positioning of directional and site-specific recombination owing to formulated primer design. ABI-REC is a novel approach to DNA engineering and gene functional analysis.
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Affiliation(s)
- Yanzhen Bi
- Hubei Key Laboratory of Animal Embryo Engineering and Molecular Breeding, Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Science, Wuhan 430064, China.
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An Y, Chen L, Sun S, Lv A, Wu W. QuikChange shuffling: a convenient and robust method for site-directed mutagenesis and random recombination of homologous genes. N Biotechnol 2011; 28:320-5. [DOI: 10.1016/j.nbt.2011.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 02/12/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
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Engineering Klebsiella sp. 601 multicopper oxidase enhances the catalytic efficiency towards phenolic substrates. BMC BIOCHEMISTRY 2011; 12:30. [PMID: 21624144 PMCID: PMC3123277 DOI: 10.1186/1471-2091-12-30] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 05/31/2011] [Indexed: 11/30/2022]
Abstract
Background Structural comparison between bacterial CueO and fungal laccases has suggested that a charged residue Glu (E106) in CueO replaces the corresponding residue Phe in fungal laccases at the gate of the tunnel connecting type II copper to the protein surface and an extra α-helix (L351-G378) near the type I copper site covers the substrate binding pocket and might compromise the electron transfer from substrate to type I copper. To test this hypothesis, several mutants were made in Klebsiella sp. 601 multicopper oxidase, which is highly homologous to E. coli CueO with a similarity of 90% and an identity of 78%. Results The E106F mutant gave smaller Km (2.4-7fold) and kcat (1-4.4 fold) values for all three substrates DMP, ABTS and SGZ as compared with those for the wild-type enzyme. Its slightly larger kcat/Km values for three substrates mainly come from the decreased Km. Deleting α-helix (L351-G378) resulted in the formation of inactive inclusion body when the mutant Δα351-378 was expressed in E. coli. Another mutant α351-380M was then made via substitution of seven amino acid residues in the α-helix (L351-G378) region. The α351-380M mutant was active, and displayed a far-UV CD spectrum markedly different from that for wild-type enzyme. Kinetic studies showed the α351-380M mutant gave very low Km values for DMP, ABTS and SGZ, 4.5-, 1.9- and 7-fold less than those for the wild type. In addition, kcat/Km values were increased, 9.4-fold for DMP, similar for ABTS and 3-fold for SGZ. Conclusion The Glu residue at position 106 appears not to be the only factor affecting the copper binding, and it may also play a role in maintaining enzyme conformation. The α-helix (L351-G378) may not only block access to the type I copper site but also play a role in substrate specificities of bacterial MCOs. The α351-380M mutant catalyzing oxidation of the phenolic substrate DMP effectively would be very useful in green chemistry.
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Fu D, Li Z, Huang H, Yuan T, Shi P, Luo H, Meng K, Yang P, Yao B. Catalytic efficiency of HAP phytases is determined by a key residue in close proximity to the active site. Appl Microbiol Biotechnol 2011; 90:1295-302. [PMID: 21380516 DOI: 10.1007/s00253-011-3171-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 01/31/2011] [Accepted: 02/09/2011] [Indexed: 11/24/2022]
Abstract
The maximum activity of Yersinia enterocolitica phytase (YeAPPA) occurs at pH 5.0 and 45 °C, and notably, its specific activity (3.28 ± 0.24 U mg(-1)) is 800-fold less than that of its Yersinia kristeensenii homolog (YkAPPA; 88% amino acid sequence identity). Sequence alignment and molecular modeling show that the arginine at position 79 (Arg79) in YeAPPA corresponding to Gly in YkAPPA as well as other histidine acid phosphatase (HAP) phytases is the only non-conserved residue near the catalytic site. To characterize the effects of the corresponding residue on the specific activities of HAP phytases, Escherichia coli EcAPPA, a well-characterized phytase with a known crystal structure, was selected for mutagenesis-its Gly73 was replaced with Arg, Asp, Glu, Ser, Thr, Leu, or Tyr. The results show that the specific activities of all of the corresponding EcAPPA mutants (17-2,400 U mg(-1)) were less than that of the wild-type phytase (3,524 U mg(-1)), and the activity levels were approximately proportional to the molecular volumes of the substituted residues' side chains. Site-directed replacement of Arg79 in YeAPPA (corresponding to Gly73 of EcAPPA) with Ser, Leu, and Gly largely increased the specific activity, which further verified the key role of the residue at position 79 for determining phytase activity. Thus, a new determinant that influences the catalytic efficiency of HAP phytases has been identified.
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Affiliation(s)
- Dawei Fu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China
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Heterodimer of two bHLH-PAS proteins mediates juvenile hormone-induced gene expression. Proc Natl Acad Sci U S A 2010; 108:638-43. [PMID: 21187375 DOI: 10.1073/pnas.1013914108] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Juvenile hormone (JH) plays crucial roles in many aspects of insect life. The Methoprene-tolerant (Met) gene product, a member of the bHLH-PAS family of transcriptional regulators, has been demonstrated to be a key component of the JH signaling pathway. However, the molecular function of Met in JH-induced signal transduction and gene regulation remains to be fully elucidated. Here we show that a transcriptional coactivator of the ecdysteroid receptor complex, FISC, acts as a functional partner of Met in mediating JH-induced gene expression. Met and FISC appear to use their PAS domains to form a dimer only in the presence of JH or JH analogs. In newly emerged adult female mosquitoes, expression of some JH responsive genes is considerably dampened when Met or FISC is depleted by RNAi. Met and FISC are found to be associated with the promoter of the early trypsin gene (AaET) when transcription of this gene is activated by JH. A juvenile hormone response element (JHRE) has been identified in the AaET upstream regulatory region and is bound in vitro by the Met-FISC complex present in the nuclear protein extracts of previtellogenic adult female mosquitoes. In addition, the Drosophila homologs of Met and FISC can also use this mosquito JHRE to activate gene transcription in response to JH in a cell transfection assay. Together, the evidence indicates that Met and FISC form a functional complex on the JHRE in the presence of JH and directly activate transcription of JH target genes.
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A new method for multi-site-directed mutagenesis. Anal Biochem 2010; 406:83-5. [PMID: 20547136 DOI: 10.1016/j.ab.2010.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/08/2010] [Accepted: 06/08/2010] [Indexed: 11/22/2022]
Abstract
A modified method for multi-site-directed mutagenesis was developed here based on polymerase chain reaction (PCR), DpnI digestion, and overlap extension. It needs only methylated plasmids obtained by Dam methyltransferase or plasmids from dam(+)Escherichia coli containing target gene. The procedure consists of PCR, DpnI digestion, overlap extension PCR, and plasmid transformation. The method was developed for multi-site-directed mutagenesis, including close proximity of mutation sites. It does not require 5'-phosphorylated primers and ligation and, thus, significantly simplifies the routine work and reduces the experimental cost for multi-site-directed mutagenesis.
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A series of novel directional cloning and expression vectors for blunt-end ligation of PCR products. Biotechnol Lett 2010; 32:439-43. [PMID: 19915798 DOI: 10.1007/s10529-009-0166-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/23/2009] [Accepted: 10/26/2009] [Indexed: 10/20/2022]
Abstract
Novel directional cloning and expression vectors were developed for blunt-end ligation of PCR products that are suitable for high-throughput cloning and simplifying the screening procedure. The PCR products, without further processing, are cloned into vectors digested with SchI and, following transformation, the desired recombinants give typical blue colonies on selectable plates. The principle of this selection strategy is that the construction also generates a full-length ideal lacO gene. To the best of our knowledge, this is the first time that this lacO reconstruction strategy has been applied in the selection of recombinants.
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Rao B, Zhong X, Wang Y, Wu Q, Jiang Z, Ma L. Efficient vectors for expression cloning of large numbers of PCR fragments inP. pastoris. Yeast 2010; 27:285-92. [DOI: 10.1002/yea.1753] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Yang J, Xu J, Zhong X, Zhang Y, Wu Q, Li W, Zhang X, Zhen P, Yang X, Chen L, Wang Y, Zhu D, Zhai C, Ma L. An advanced blue–white screening method for construction of shRNA expression vectors. Biochem Biophys Res Commun 2009; 390:97-102. [DOI: 10.1016/j.bbrc.2009.09.074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 09/16/2009] [Indexed: 01/30/2023]
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Zhu D, Zhong X, Tan R, Chen L, Huang G, Li J, Sun X, Xu L, Chen J, Ou Y, Zhang T, Yuan D, Zhang Z, Shu W, Ma L. High-throughput cloning of human liver complete open reading frames using homologous recombination in Escherichia coli. Anal Biochem 2009; 397:162-7. [PMID: 19835833 DOI: 10.1016/j.ab.2009.10.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 10/06/2009] [Accepted: 10/09/2009] [Indexed: 11/19/2022]
Abstract
In this article, we describe a high-throughput cloning method, seamless enzyme-free cloning (SEFC), which allows one-step assembly of DNA fragments in vivo via homologous recombination in Escherichia coli. In the method, the desired open reading frame (ORF) is amplified by use of ORF-specific primers with flanking sequences identical to the two ends of a linearized vector. The polymerase chain reaction (PCR) product and the linearized vector are then cotransformed into E. coli cells, where the ORF is incorporated into the vector in vivo. SEFC is a simple, reliable, and inexpensive method of cloning in which PCR fragments are fused into expression vectors without unwanted amino acids or extra in vitro manipulations apart from the single PCR amplification step. Using this method, we successfully cloned human liver complete ORFs into the yeast AD and DB vectors and generated a clone resource of 4964 AD-ORFs and 4676 DB-ORFs in 3months. This approach will be useful for daily DNA cloning and for creating proteome-scale clone resources.
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Affiliation(s)
- Dewu Zhu
- Institute of Biochemistry and Molecular Biology, Hubei University, Wuhan 430062, China
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Xu J, Zeng JQ, Wan G, Hu GB, Yan H, Ma LX. Construction of siRNA/miRNA expression vectors based on a one-step PCR process. BMC Biotechnol 2009; 9:53. [PMID: 19490634 PMCID: PMC2700792 DOI: 10.1186/1472-6750-9-53] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Accepted: 06/02/2009] [Indexed: 11/20/2022] Open
Abstract
Background RNA interference (RNAi) has become a powerful means for silencing target gene expression in mammalian cells and is envisioned to be useful in therapeutic approaches to human disease. In recent years, high-throughput, genome-wide screening of siRNA/miRNA libraries has emerged as a desirable approach. Current methods for constructing siRNA/miRNA expression vectors require the synthesis of long oligonucleotides, which is costly and suffers from mutation problems. Results Here we report an ingenious method to solve traditional problems associated with construction of siRNA/miRNA expression vectors. We synthesized shorter primers (< 50 nucleotides) to generate a linear expression structure by PCR. The PCR products were directly transformed into chemically competent E. coli and converted to functional vectors in vivo via homologous recombination. The positive clones could be easily screened under UV light. Using this method we successfully constructed over 500 functional siRNA/miRNA expression vectors. Sequencing of the vectors confirmed a high accuracy rate. Conclusion This novel, convenient, low-cost and highly efficient approach may be useful for high-throughput assays of RNAi libraries.
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Affiliation(s)
- Jun Xu
- Institute of Molecular Biology, Biology Faculty of Hubei University, Wuhan, Hubei Province, PR China.
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Kato Y, Arakawa N, Masuishi Y, Kawasaki H, Hirano H. Mutagenesis of longer inserts by the ligation of two PCR fragments amplified with a mutation primer. J Biosci Bioeng 2009; 107:95-7. [PMID: 19147118 DOI: 10.1016/j.jbiosc.2008.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 09/11/2008] [Indexed: 11/29/2022]
Abstract
We report a method for efficient mutagenesis of DNA in large vectors without subcloning. Two segments of the target DNA sequence, one having a mutation introduced via a mutant primer, were amplified by PCR and then the purified fragments were ligated to a vector. The mutation efficiency was nearly 100%.
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Affiliation(s)
- Yu Kato
- Supramolecular Biology, International Graduate School of Arts and Sciences, Yokohama City University, Suehiro-cho 1-7-29, Tsurumi-ku, Yokohama 230-0045, Japan
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Liu H, Naismith JH. An efficient one-step site-directed deletion, insertion, single and multiple-site plasmid mutagenesis protocol. BMC Biotechnol 2008; 8:91. [PMID: 19055817 PMCID: PMC2629768 DOI: 10.1186/1472-6750-8-91] [Citation(s) in RCA: 777] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Accepted: 12/04/2008] [Indexed: 11/24/2022] Open
Abstract
Background Mutagenesis plays an essential role in molecular biology and biochemistry. It has also been used in enzymology and protein science to generate proteins which are more tractable for biophysical techniques. The ability to quickly and specifically mutate a residue(s) in protein is important for mechanistic and functional studies. Although many site-directed mutagenesis methods have been developed, a simple, quick and multi-applicable method is still desirable. Results We have developed a site-directed plasmid mutagenesis protocol that preserved the simple one step procedure of the QuikChange™ site-directed mutagenesis but enhanced its efficiency and extended its capability for multi-site mutagenesis. This modified protocol used a new primer design that promoted primer-template annealing by eliminating primer dimerization and also permitted the newly synthesized DNA to be used as the template in subsequent amplification cycles. These two factors we believe are the main reasons for the enhanced amplification efficiency and for its applications in multi-site mutagenesis. Conclusion Our modified protocol significantly increased the efficiency of single mutation and also allowed facile large single insertions, deletions/truncations and multiple mutations in a single experiment, an option incompatible with the standard QuikChange™. Furthermore the new protocol required significantly less parental DNA which facilitated the DpnI digestion after the PCR amplification and enhanced the overall efficiency and reliability. Using our protocol, we generated single site, multiple single-site mutations and a combined insertion/deletion mutations. The results demonstrated that this new protocol imposed no additional reagent costs (beyond basic QuikChange™) but increased the overall success rates.
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Affiliation(s)
- Huanting Liu
- SSPF, Centre for Biomolecular Science, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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