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Javid M, Shahverdi AR, Ghasemi A, Moosavi-Movahedi AA, Ebrahim-Habibi A, Sepehrizadeh Z. Decoding the Structure-Function Relationship of the Muramidase Domain in E. coli O157.H7 Bacteriophage Endolysin: A Potential Building Block for Chimeric Enzybiotics. Protein J 2024; 43:522-543. [PMID: 38662183 DOI: 10.1007/s10930-024-10195-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2024] [Indexed: 04/26/2024]
Abstract
Bacteriophage endolysins are potential alternatives to conventional antibiotics for treating multidrug-resistant gram-negative bacterial infections. However, their structure-function relationships are poorly understood, hindering their optimization and application. In this study, we focused on the individual functionality of the C-terminal muramidase domain of Gp127, a modular endolysin from E. coli O157:H7 bacteriophage PhaxI. This domain is responsible for the enzymatic activity, whereas the N-terminal domain binds to the bacterial cell wall. Through protein modeling, docking experiments, and molecular dynamics simulations, we investigated the activity, stability, and interactions of the isolated C-terminal domain with its ligand. We also assessed its expression, solubility, toxicity, and lytic activity using the experimental data. Our results revealed that the C-terminal domain exhibits high activity and toxicity when tested individually, and its expression is regulated in different hosts to prevent self-destruction. Furthermore, we validated the muralytic activity of the purified refolded protein by zymography and standardized assays. These findings challenge the need for the N-terminal binding domain to arrange the active site and adjust the gap between crucial residues for peptidoglycan cleavage. Our study shed light on the three-dimensional structure and functionality of muramidase endolysins, thereby enriching the existing knowledge pool and laying a foundation for accurate in silico modeling and the informed design of next-generation enzybiotic treatments.
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Affiliation(s)
- Mehri Javid
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy & Biotechnology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Reza Shahverdi
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy & Biotechnology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Atiyeh Ghasemi
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | | | - Azadeh Ebrahim-Habibi
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy & Biotechnology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
- Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
| | - Zargham Sepehrizadeh
- Department of Pharmaceutical Biotechnology, Faculty of Pharmacy & Biotechnology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
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Sisson HM, Fagerlund RD, Jackson SA, Briers Y, Warring SL, Fineran PC. Antibacterial synergy between a phage endolysin and citric acid against the Gram-negative kiwifruit pathogen Pseudomonas syringae pv. actinidiae. Appl Environ Microbiol 2024; 90:e0184623. [PMID: 38319087 PMCID: PMC10952447 DOI: 10.1128/aem.01846-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/04/2024] [Indexed: 02/07/2024] Open
Abstract
Horticultural diseases caused by bacterial pathogens provide an obstacle to crop production globally. Management of the infection of kiwifruit by the Gram-negative phytopathogen Pseudomonas syringae pv. actinidiae (Psa) currently includes copper and antibiotics. However, the emergence of bacterial resistance and a changing regulatory landscape are providing the impetus to develop environmentally sustainable antimicrobials. One potential strategy is the use of bacteriophage endolysins, which degrade peptidoglycan during normal phage replication, causing cell lysis and the release of new viral progeny. Exogenous use of endolysins as antimicrobials is impaired by the outer membrane of Gram-negative bacteria that provides an impermeable barrier and prevents endolysins from accessing their target peptidoglycan. Here, we describe the synergy between citric acid and a phage endolysin, which results in a reduction of viable Psa below detection. We show that citric acid drives the destabilization of the outer membrane via acidification and sequestration of divalent cations from the lipopolysaccharide, which is followed by the degradation of the peptidoglycan by the endolysin. Scanning electron microscopy revealed clear morphological differences, indicating cell lysis following the endolysin-citric acid treatment. These results show the potential for citric acid-endolysin combinations as a possible antimicrobial approach in agricultural applications. IMPORTANCE The phytopathogen Pseudomonas syringae pv. actinidiae (Psa) causes major impacts to kiwifruit horticulture, and the current control strategies are heavily reliant on copper and antibiotics. The environmental impact and increasing resistance to these agrichemicals are driving interest in alternative antimicrobials including bacteriophage-derived therapies. In this study, we characterize the endolysin from the Otagovirus Psa374 which infects Psa. When combined with citric acid, this endolysin displays an impressive antibacterial synergy to reduce viable Psa below the limit of detection. The use of citric acid as a synergistic agent with endolysins has not been extensively studied and has never been evaluated against a plant pathogen. We determined that the synergy involved a combination of the chelation activity of citric acid, acidic pH, and the specific activity of the ΦPsa374 endolysin. Our study highlights an exciting opportunity for alternative antimicrobials in agriculture.
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Affiliation(s)
- Hazel M. Sisson
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
| | - Robert D. Fagerlund
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
| | - Simon A. Jackson
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
| | - Yves Briers
- Laboratory of Applied Biotechnology, Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Suzanne L. Warring
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Peter C. Fineran
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
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Nair G, Jain V. An intramolecular cross-talk in D29 mycobacteriophage endolysin governs the lytic cycle and phage-host population dynamics. SCIENCE ADVANCES 2024; 10:eadh9812. [PMID: 38335296 PMCID: PMC10857449 DOI: 10.1126/sciadv.adh9812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 01/10/2024] [Indexed: 02/12/2024]
Abstract
D29 mycobacteriophage encodes LysA endolysin, which mediates mycobacterial host cell lysis by targeting its peptidoglycan layer, thus projecting itself as a potential therapeutic. However, the regulatory mechanism of LysA during the phage lytic cycle remains ill defined. Here, we show that during D29 lytic cycle, structural and functional regulation of LysA not only orchestrates host cell lysis but also is critical for maintaining phage-host population dynamics by governing various phases of lytic cycle. We report that LysA exists in two conformations, of which only one is active, and the protein undergoes a host peptidoglycan-dependent conformational switch to become active for carrying out endogenous host cell lysis. D29 maintains a pool of inactive LysA, allowing complete assembly of phage progeny, thus helping avoid premature host lysis. In addition, we show that the switch reverses after lysis, thus preventing exogenous targeting of bystanders, which otherwise negatively affects phage propagation in the environment.
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Affiliation(s)
- Gokul Nair
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal 462066, Madhya Pradesh, India
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Vázquez R, Seoane-Blanco M, Rivero-Buceta V, Ruiz S, van Raaij MJ, García P. Monomodular Pseudomonas aeruginosa phage JG004 lysozyme (Pae87) contains a bacterial surface-active antimicrobial peptide-like region and a possible substrate-binding subdomain. ACTA CRYSTALLOGRAPHICA SECTION D STRUCTURAL BIOLOGY 2022; 78:435-454. [PMID: 35362467 PMCID: PMC8972805 DOI: 10.1107/s2059798322000936] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/27/2022] [Indexed: 11/10/2022]
Abstract
The structure of the monomodular Pseudomonas aeruginosa bacteriophage JG004 lysin Pae87 is presented and investigated in relation to repurposing its function as an antimicrobial agent. The structure with its peptidoglycan ligand revealed a possible cell-wall-binding region. A C-terminal antimicrobial peptide-like region is shown to be important for disrupting the bacterial cell wall. Phage lysins are a source of novel antimicrobials to tackle the bacterial antibiotic-resistance crisis. The engineering of phage lysins is being explored as a game-changing technological strategy to introduce a more precise approach in the way in which antimicrobial therapy is applied. Such engineering efforts will benefit from a better understanding of lysin structure and function. In this work, the antimicrobial activity of the endolysin from Pseudomonas aeruginosa phage JG004, termed Pae87, has been characterized. This lysin had previously been identified as an antimicrobial agent candidate that is able to interact with the Gram-negative surface and disrupt it. Further evidence is provided here based on a structural and biochemical study. A high-resolution crystal structure of Pae87 complexed with a peptidoglycan fragment showed a separate substrate-binding region within the catalytic domain, 18 Å away from the catalytic site and located on the opposite side of the lysin molecule. This substrate-binding region was conserved among phylogenetically related lysins lacking an additional cell-wall-binding domain, but not among those containing such a module. Two glutamic acids were identified to be relevant for the peptidoglycan-degradation activity, although the antimicrobial activity of Pae87 was seemingly unrelated. In contrast, an antimicrobial peptide-like region within the Pae87 C-terminus, named P87, was found to be able to actively disturb the outer membrane and display antibacterial activity by itself. Therefore, an antimicrobial mechanism for Pae87 is proposed in which the P87 peptide plays the role of binding to the outer membrane and disrupting the cell-wall function, either with or without the participation of the catalytic activity of Pae87.
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