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Forrest S, Welch M. Arming the troops: Post-translational modification of extracellular bacterial proteins. Sci Prog 2020; 103:36850420964317. [PMID: 33148128 PMCID: PMC10450907 DOI: 10.1177/0036850420964317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Protein secretion is almost universally employed by bacteria. Some proteins are retained on the cell surface, whereas others are released into the extracellular milieu, often playing a key role in virulence. In this review, we discuss the diverse types and potential functions of post-translational modifications (PTMs) occurring to extracellular bacterial proteins.
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Affiliation(s)
- Suzanne Forrest
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Martin Welch
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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Teige LH, Kumar S, Johansen GM, Wessel Ø, Vendramin N, Lund M, Rimstad E, Boysen P, Dahle MK. Detection of Salmonid IgM Specific to the Piscine Orthoreovirus Outer Capsid Spike Protein Sigma 1 Using Lipid-Modified Antigens in a Bead-Based Antibody Detection Assay. Front Immunol 2019; 10:2119. [PMID: 31552049 PMCID: PMC6743345 DOI: 10.3389/fimmu.2019.02119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 08/22/2019] [Indexed: 11/13/2022] Open
Abstract
Bead-based multiplex immunoassays are promising tools for determination of the specific humoral immune response. In this study, we developed a multiplexed bead-based immunoassay for the detection of Atlantic salmon (Salmo salar) antibodies against Piscine orthoreovirus (PRV). Three different genotypes of PRV (PRV-1, PRV-2, and PRV-3) cause disease in farmed salmonids. The PRV outer capsid spike protein σ1 is predicted to be a host receptor binding protein and a target for neutralizing and protective antibodies. While recombinant σ1 performed poorly as an antigen to detect specific antibodies, N-terminal lipid modification of recombinant PRV-1 σ1 enabled sensitive detection of specific IgM in the bead-based assay. The specificity of anti-PRV-1 σ1 antibodies was confirmed by western blotting and pre-adsorption of plasma. Binding of non-specific IgM to beads coated with control antigens also increased after PRV infection, indicating a release of polyreactive antibodies. This non-specific binding was reduced by heat treatment of plasma. The same immunoassay also detected anti-PRV-3 σ1 antibodies from infected rainbow trout. In summary, a refined bead based immunoassay created by N-terminal lipid-modification of the PRV-1 σ1 antigen allowed sensitive detection of anti-PRV-1 and anti-PRV-3 antibodies from salmonids.
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Affiliation(s)
- Lena Hammerlund Teige
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Subramani Kumar
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway.,Stem Cell and Cancer Biology Lab, Centre for Biotechnology, Anna University, Chennai, India
| | - Grethe M Johansen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Øystein Wessel
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Niccolò Vendramin
- National Institute of Aquatic Resources, Technical University of Denmark, Lyngby, Denmark
| | - Morten Lund
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway.,PatoGen, Alesund, Norway
| | - Espen Rimstad
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Preben Boysen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Maria K Dahle
- Department of Fish Health, Norwegian Veterinary Institute, Oslo, Norway
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Murugan V, Sankaran K. Bacterial Lipid Modification of ICP11 and a New ELISA System Applicable for WSSV Infection Detection. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2018; 20:375-384. [PMID: 29656308 DOI: 10.1007/s10126-018-9815-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 12/08/2017] [Indexed: 06/08/2023]
Abstract
In ELISA, a popular analytical diagnostic tool, the stable non-covalent immobilization (coating) of hydrophilic proteins/peptides on to hydrophobic polystyrene surface has remained a major common challenge. Recombinant bacterial lipid modification of proteins in Escherichia coli system has been shown in this study to solve this problem owing to the hydrophobic anchorage provided by three fatty acyl groups in N-acyl-S-diacylglyceryl Cys at the N-terminus. Exploiting this first post-translational protein engineering, the most abundantly expressed white spot syndrome viral protein ICP11 was lipid-modified and tested as a new target in a new ELISA method useful to shrimp farming. The lipid served as a potent adjuvant to enhance the titer (16 times) of higher affinity antibodies where amino terminal lipoamino acid N-acyl-S-diacylglyceryl cysteine of bacterial lipoproteins induce inflammatory responses through TLR and stimulate humoral immune responses without additional adjuvant and also aided in the immobilization of even a few nanograms of ICP11. Competition between the immobilized and the free antigen from the sample provided a sensitive measure of antigen in the infected shrimp tissues. The detection limit for ICP11 protein using competitive ELISA was 250 pg and the linear range of the assay was 15-240 ng.
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Affiliation(s)
- Vidhyapriya Murugan
- Centre for Biotechnology, Anna University, Guindy, Chennai, Tamil Nadu, 600025, India
| | - Krishnan Sankaran
- Centre for Biotechnology, Anna University, Guindy, Chennai, Tamil Nadu, 600025, India.
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Mao G, Zhao Y, Kang X, Li Z, Zhang Y, Wang X, Sun F, Sankaran K, Zhang XC. Crystal structure of E. coli lipoprotein diacylglyceryl transferase. Nat Commun 2016; 7:10198. [PMID: 26729647 PMCID: PMC4728403 DOI: 10.1038/ncomms10198] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 11/16/2015] [Indexed: 02/07/2023] Open
Abstract
Lipoprotein biogenesis is essential for bacterial survival. Phosphatidylglycerol:prolipoprotein diacylglyceryl transferase (Lgt) is an integral membrane enzyme that catalyses the first reaction of the three-step post-translational lipid modification. Deletion of the lgt gene is lethal to most Gram-negative bacteria. Here we present the crystal structures of Escherichia coli Lgt in complex with phosphatidylglycerol and the inhibitor palmitic acid at 1.9 and 1.6 Å resolution, respectively. The structures reveal the presence of two binding sites and support the previously reported structure–function relationships of Lgt. Complementation results of lgt-knockout cells with different mutant Lgt variants revealed critical residues, including Arg143 and Arg239, that are essential for diacylglyceryl transfer. Using a GFP-based in vitro assay, we correlated the activities of Lgt with structural observations. Together, the structural and biochemical data support a mechanism whereby substrate and product, lipid-modified lipobox-containing peptide, enter and leave the enzyme laterally relative to the lipid bilayer. Bacterial lipoproteins have important biological functions, and the lipoprotien biogenesis enzyme Lgt is essential in most gram-negative bacteria. Here, the authors use structural and biochemical techniques to shed light on the function of Lgt in post-translational transacylation modification.
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Affiliation(s)
- Guotao Mao
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Zhao
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Xusheng Kang
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Zhijie Li
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Yan Zhang
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Xianping Wang
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | - Fei Sun
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
| | | | - Xuejun C Zhang
- National Laboratory of Macromolecules, National Center of Protein Science - Beijing, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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