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da Cruz Nizer WS, Allison KN, Adams ME, Vargas MA, Ahmed D, Beaulieu C, Raju D, Cassol E, Howell PL, Overhage J. The role of exopolysaccharides Psl and Pel in resistance of Pseudomonas aeruginosa to the oxidative stressors sodium hypochlorite and hydrogen peroxide. Microbiol Spectr 2024:e0092224. [PMID: 39194290 DOI: 10.1128/spectrum.00922-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 07/01/2024] [Indexed: 08/29/2024] Open
Abstract
Pseudomonas aeruginosa is well-known for its antimicrobial resistance and the ability to survive in harsh environmental conditions due to an abundance of resistance mechanisms, including the formation of biofilms and the production of exopolysaccharides. Exopolysaccharides are among the major components of the extracellular matrix in biofilms and aggregates of P. aeruginosa. Although their contribution to antibiotic resistance has been previously shown, their roles in resistance to oxidative stressors remain largely elusive. Here, we studied the function of the exopolysaccharides Psl and Pel in the resistance of P. aeruginosa to the commonly used disinfectants and strong oxidizing agents NaOCl and H2O2. We observed that the simultaneous inactivation of Psl and Pel in P. aeruginosa PAO1 mutant strain ∆pslA pelF resulted in a significant increase in susceptibility to both NaOCl and H2O2. Further analyses revealed that Pel is more important for oxidative stress resistance in P. aeruginosa and that the form of Pel (i.e., cell-associated or cell-free) did not affect NaOCl susceptibility. Additionally, we show that Psl/Pel-negative strains are protected against oxidative stress in co-culture biofilms with P. aeruginosa PAO1 WT. Taken together, our results demonstrate that the EPS matrix and, more specifically, Pel exhibit protective functions against oxidative stressors such as NaOCl and H2O2 in P. aeruginosa. IMPORTANCE Biofilms are microbial communities of cells embedded in a self-produced polymeric matrix composed of polysaccharides, proteins, lipids, and extracellular DNA. Biofilm bacteria have been shown to possess unique characteristics, including increased stress resistance and higher antimicrobial tolerance, leading to failures in bacterial eradication during chronic infections or in technical settings, including drinking and wastewater industries. Previous studies have shown that in addition to conferring structure and stability to biofilms, the polysaccharides Psl and Pel are also involved in antibiotic resistance. This work provides evidence that these biofilm matrix components also contribute to the resistance of Pseudomonas aeruginosa to oxidative stressors including the widely used disinfectant NaOCl. Understanding the mechanisms by which bacteria escape antimicrobial agents, including strong oxidants, is urgently needed in the fight against antimicrobial resistance and will help in developing new strategies to eliminate resistant strains in any environmental, industrial, and clinical setting.
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Affiliation(s)
| | - Kira N Allison
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Madison E Adams
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Mario A Vargas
- Program in Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Duale Ahmed
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Carole Beaulieu
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Deepa Raju
- Program in Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Edana Cassol
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - P Lynne Howell
- Program in Medicine, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Joerg Overhage
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
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2
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Datta S, Singh V, Nag S, Roy DN. Marine-Derived Cytosine Arabinoside (Ara-C) Inhibits Biofilm Formation by Inhibiting PEL Operon Proteins (Pel A and Pel B) of Pseudomonas aeruginosa: An In Silico Approach. Mol Biotechnol 2024:10.1007/s12033-024-01169-8. [PMID: 38739212 DOI: 10.1007/s12033-024-01169-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 04/03/2024] [Indexed: 05/14/2024]
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is a gram-negative biofilm-forming opportunistic human pathogen whose vital mechanism is biofilm formation for better survival. PelA and PelB proteins of the PEL operon are essential for bacterial-synthesized pellicle polysaccharide (PEL), which is a vital structural component of the biofilm. It helps in adherence of biofilm on the surface and maintenance of cell-to-cell interactions and with other matrix components. Here, in-silico molecular docking and simulation studies were performed against PelA and PelB using ten natural bioactive compounds, individually [podocarpic acids, ferruginol, scopadulcic acid B, pisiferic acid, metachromin A, Cytarabine (cytosine arabinoside; Ara-C), ursolic acid, oleanolic acid, maslinic acid, and betulinic acid], those have already been established as anti-infectious compounds. The results obtained from AutoDock and Glide-Schordinger stated that a marine-derived cytosine arabinoside (Ara-C) among the ten compounds binds active sites of PelA and PelB, exhibiting strong binding affinity [Trp224 (hydrogen), Ser219 (polar), Val234 (hydrophobic) for PelA; Leu365 and Glu389 (hydrogen), Gln366 (polar) for PelB] with high negative binding energy - 5.518 kcal/mol and - 6.056 kcal/mol, respectively. The molecular dynamic and simulation studies for 100 ns showed the MMGBSA binding energy scores are - 16.4 kcal/mol (Ara-C with PelA), and - 22.25 kcal/mol (Ara-C with PelB). Further, ADME/T studies indicate the IC50 values of AraC are 6.10 mM for PelA and 18.78 mM for PelB, which is a comparatively very low dose. The zero violation of Lipinski's Rule of Five further established that Ara-C is a good candidate for drug development. Thus, Ara-C could be considered a potent anti-biofilm compound against PEL operon-dependent biofilm formation of P. aeruginosa.
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Affiliation(s)
- Susmita Datta
- Department of Chemical Engineering, National Institute of Technology - Agartala, Agartala, Tripura, India
| | - Vishal Singh
- Centre for Biotechnology, School of Pharmaceutical Sciences, Siksha 'O' Anusandhan (Deemed to be university), Bhubaneswar, Odisha, India
| | - Soma Nag
- Department of Chemical Engineering, National Institute of Technology - Agartala, Agartala, Tripura, India.
| | - Dijendra Nath Roy
- Department of Biotechnology, National Institute of Technology - Raipur, Raipur, Chhattisgarh, India.
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Panagaki F, Tapia-Rojo R, Zhu T, Milmoe N, Paracuellos P, Board S, Mora M, Walker J, Rostkova E, Stannard A, Infante E, Garcia-Manyes S. Structural anisotropy results in mechano-directional transport of proteins across nuclear pores. NATURE PHYSICS 2024; 20:1180-1193. [PMID: 39036650 PMCID: PMC11254768 DOI: 10.1038/s41567-024-02438-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 02/08/2024] [Indexed: 07/23/2024]
Abstract
The nuclear pore complex regulates nucleocytoplasmic transport by means of a tightly synchronized suite of biochemical reactions. The physicochemical properties of the translocating cargos are emerging as master regulators of their shuttling dynamics. As well as being affected by molecular weight and surface-exposed amino acids, the kinetics of the nuclear translocation of protein cargos also depend on their nanomechanical properties, yet the mechanisms underpinning the mechanoselectivity of the nuclear pore complex are unclear. Here we show that proteins with locally soft regions in the vicinity of the nuclear-localization sequence exhibit higher nuclear-import rates, and that such mechanoselectivity is specifically impaired upon knocking down nucleoporin 153, a key protein in the nuclear pore complex. This allows us to design a short, easy-to-express and chemically inert unstructured peptide tag that accelerates the nuclear-import rate of stiff protein cargos. We also show that U2OS osteosarcoma cells expressing the peptide-tagged myocardin-related transcription factor import this mechanosensitive protein to the nucleus at higher rates and display faster motility. Locally unstructured regions lower the free-energy barrier of protein translocation and might offer a control mechanism for nuclear mechanotransduction.
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Affiliation(s)
- Fani Panagaki
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Rafael Tapia-Rojo
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Tong Zhu
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Natalie Milmoe
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Patricia Paracuellos
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Stephanie Board
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Marc Mora
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Jane Walker
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Elena Rostkova
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Andrew Stannard
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Elvira Infante
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
| | - Sergi Garcia-Manyes
- Single Molecule Mechanobiology Laboratory, The Francis Crick Institute, London, UK
- Department of Physics, Randall Centre for Cell and Molecular Biophysics, Centre for the Physical Science of Life and London Centre for Nanotechnology, King’s College London, London, UK
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4
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Amyx-Sherer K, Reichhardt C. Challenges and opportunities in elucidating the structures of biofilm exopolysaccharides: A case study of the Pseudomonas aeruginosa exopolysaccharide called Pel. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:361-369. [PMID: 37919227 DOI: 10.1002/mrc.5405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 10/09/2023] [Accepted: 10/17/2023] [Indexed: 11/04/2023]
Abstract
Biofilm formation protects bacteria from antibiotic treatment and host immune responses, making biofilm infections difficult to treat. Within biofilms, bacterial cells are entangled in a self-produced extracellular matrix that typically includes exopolysaccharides. Molecular-level descriptions of biofilm matrix components, especially exopolysaccharides, have been challenging to attain due to their complex nature and lack of solubility and crystallinity. Solid-state nuclear magnetic resonance (NMR) has emerged as a key tool to determine the structure of biofilm matrix exopolysaccharides without degradative sample preparation. In this review, we discuss challenges of studying biofilm matrix exopolysaccharides and opportunities to develop solid-state NMR approaches to study these generally intractable materials. We specifically highlight investigations of the exopolysaccharide called Pel made by the opportunistic pathogen, Pseudomonas aeruginosa. We provide a roadmap for determining exopolysaccharide structure and discuss future opportunities to study such systems using solid-state NMR. The strategies discussed for elucidating biofilm exopolysaccharide structure should be broadly applicable to studying the structures of other glycans.
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Affiliation(s)
- Kristen Amyx-Sherer
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Courtney Reichhardt
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
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5
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Wang L, Zheng J, Hou W, Zhang C, Zhang J, Fan X, Zhang H, Han Y. The Anti-Microbial Peptide Citrocin Controls Pseudomonas aeruginosa Biofilms by Breaking Down Extracellular Polysaccharide. Int J Mol Sci 2024; 25:4122. [PMID: 38612931 PMCID: PMC11012989 DOI: 10.3390/ijms25074122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/31/2024] [Accepted: 04/05/2024] [Indexed: 04/14/2024] Open
Abstract
Citrocin is an anti-microbial peptide that holds great potential in animal feed. This study evaluates the anti-microbial and anti-biofilm properties of Citrocin and explores the mechanism of action of Citrocin on the biofilm of P. aeruginosa. The results showed that Citrocin had a significant inhibitory effect on the growth of P. aeruginosa with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 0.3 mg/mL. All five concentrations (1/4MIC, 1/2MIC, MIC, 2MIC, and 4MIC) of Citrocin inhibited P. aeruginosa biofilm formation. Citrocin at the MIC, 2MIC and 4MIC removed 42.7%, 76.0% and 83.2% of mature biofilms, respectively, and suppressed the swarming motility, biofilm metabolic activity and extracellular polysaccharide production of P. aeruginosa. Metabolomics analysis indicated that 0.3 mg/mL of Citrocin up- regulated 26 and down-regulated 83 metabolites, mainly comprising amino acids, fatty acids, organic acids and sugars. Glucose and amino acid metabolic pathways, including starch and sucrose metabolism as well as arginine and proline metabolism, were highly enriched by Citrocin. In summary, our research reveals the anti-biofilm mechanism of Citrocin at the metabolic level, which provides theoretical support for the development of novel anti-biofilm strategies for combatting P. aeruginosa.
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Affiliation(s)
- Liyao Wang
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
- College of Life Science and Technology, Southeast University, Nanjing 211189, China
| | - Jiaqi Zheng
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
- Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Wenchao Hou
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
| | - Chaowen Zhang
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
| | - Jie Zhang
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
| | - Xuanbo Fan
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
| | - Hongliang Zhang
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
- College of Animal Science and Technology, China Agricultural University, Beijing 100083, China
| | - Yuzhu Han
- College of Animal Science and Technology, Southwest University, Chongqing 402460, China; (L.W.); (J.Z.); (W.H.); (C.Z.); (J.Z.); (X.F.); (H.Z.)
- Chongqing Key Laboratory of Herbivore Science, Chongqing 402460, China
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6
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Guo Y, Wang Y, Xu X, Niu D, Qing Q, Wang L, Zhu J. Effects of Cold Plasma Pretreatment on the Synthesis of Polysaccharide from Pleurotus ostreatus. Appl Biochem Biotechnol 2024; 196:1977-1991. [PMID: 37458939 DOI: 10.1007/s12010-023-04662-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: 07/04/2023] [Indexed: 04/23/2024]
Abstract
Fungal polysaccharides have attracted wide attention because of their medical pharmaceutical and health care value. So far, many efforts have been made in strain improvement to produce polysaccharides on a large scale at low cost. Here, a novel cold plasma-induced strain improvement technology was employed to pretreat Pleurotus ostreatus CGMCC 5.374 by radio-frequency (RF) low-vacuum cold plasma (LVCP) for the purpose of obtaining a high-yield polysaccharide strain. The optimum pretreatment conditions including discharge power, treatment time, and working pressure were determined by single factor and orthogonal experiment in succession. Furthermore, transcriptome analysis was conducted to study the effects of RF-LVCP on cell metabolism and proliferation. Results showed that under the optimal condition of discharge power of 130 W, treatment time of 25 s and working pressure of 140 Pa, polysaccharide content in mycelium was increased by 3.16% after 6 days in comparison to the original strain. Transcriptome analysis showed that RF-LVCP is helpful for specific gene transcription profiles, Gene Ontology (GO) and KEGG pathways, of which the differentially expressed genes (DEGs) were mainly involve with the up-regulation of polysaccharide transport, physiology, synthesis and metabolism, as well as the down-regulation of polysaccharide hydrolysis and macromolecular degradation.
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Affiliation(s)
- Yan Guo
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Youjun Wang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Xiaoyan Xu
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Dongze Niu
- Institute of Urban & Rural Mining, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Qing Qing
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Liqun Wang
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China
| | - Jie Zhu
- School of Pharmacy, Changzhou University, Changzhou, 213164, Jiangsu, China.
- Institute of Urban & Rural Mining, Changzhou University, Changzhou, 213164, Jiangsu, China.
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7
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Van Loon JC, Whitfield GB, Wong N, O'Neal L, Henrickson A, Demeler B, O'Toole GA, Parsek MR, Howell PL. Binding of GTP to BifA is required for the production of Pel-dependent biofilms in Pseudomonas aeruginosa. J Bacteriol 2024; 206:e0033123. [PMID: 38197635 PMCID: PMC10882990 DOI: 10.1128/jb.00331-23] [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: 10/06/2023] [Accepted: 12/13/2023] [Indexed: 01/11/2024] Open
Abstract
The Pel exopolysaccharide is one of the most mechanistically conserved and phylogenetically diverse bacterial biofilm matrix determinants. Pel is a major contributor to the structural integrity of Pseudomonas aeruginosa biofilms, and its biosynthesis is regulated by the binding of cyclic-3',5'-dimeric guanosine monophosphate (c-di-GMP) to the PelD receptor. c-di-GMP is synthesized from two molecules of guanosine triphosphate (GTP) by diguanylate cyclases with GGDEF domains and degraded by phosphodiesterases with EAL or HD-GYP domains. As the P. aeruginosa genome encodes 43 c-di-GMP metabolic enzymes, one way signaling specificity can be achieved is through direct interaction between specific enzyme-receptor pairs. Here, we show that the inner membrane hybrid GGDEF-EAL enzyme, BifA, directly interacts with PelD via its cytoplasmic HAMP, GGDEF, and EAL domains. Despite having no catalytic function, the degenerate active site motif of the BifA GGDEF domain (GGDQF) has retained the ability to bind GTP with micromolar affinity. Mutations that abolish GTP binding result in increased biofilm formation but stable global c-di-GMP levels. Our data suggest that BifA forms a dimer in solution and that GTP binding induces conformational changes in dimeric BifA that enhance the BifA-PelD interaction and stimulate its phosphodiesterase activity, thus reducing c-di-GMP levels and downregulating Pel biosynthesis. Structural comparisons between the dimeric AlphaFold2 model of BifA and the structures of other hybrid GGDEF-EAL proteins suggest that the regulation of BifA by GTP may occur through a novel mechanism.IMPORTANCEc-di-GMP is the most common cyclic dinucleotide used by bacteria to regulate phenotypes such as motility, biofilm formation, virulence factor production, cell cycle progression, and cell differentiation. While the identification and initial characterization of c-di-GMP metabolic enzymes are well established, our understanding of how these enzymes are regulated to provide signaling specificity remains understudied. Here we demonstrate that the inactive GGDEF domain of BifA binds GTP and regulates the adjacent phosphodiesterase EAL domain, ultimately downregulating Pel-dependent P. aeruginosa biofilm formation through an interaction with PelD. This discovery adds to the growing body of literature regarding how hybrid GGDEF-EAL enzymes are regulated and provides additional precedence for studying how direct interactions between c-di-GMP metabolic enzymes and effectors result in signaling specificity.
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Affiliation(s)
- Jaime C. Van Loon
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Gregory B. Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Nicole Wong
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, Canada
| | - Lindsey O'Neal
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, Alberta, Canada
| | - G. A. O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Matthew R. Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - P. Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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Tomić N, Stevanović MM, Filipović N, Ganić T, Nikolić B, Gajić I, Ćulafić DM. Resveratrol/Selenium Nanocomposite with Antioxidative and Antibacterial Properties. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:368. [PMID: 38392741 PMCID: PMC10892210 DOI: 10.3390/nano14040368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/12/2024] [Accepted: 02/12/2024] [Indexed: 02/24/2024]
Abstract
In this work, we synthesized a new composite material comprised of previously formulated resveratrol nanobelt-like particles (ResNPs) and selenium nanoparticles (SeNPs), namely ResSeNPs. Characterization was provided by FESEM and optical microscopy, as well as by UV-Vis and FTIR spectroscopy, the last showing hydrogen bonds between ResNPs and SeNPs. DPPH, TBA, and FRAP assays showed excellent antioxidative abilities with ResNPs and SeNPs contributing mainly to lipid peroxidation inhibition and reducing/scavenging activity, respectively. The antibacterial effect against common medicinal implant colonizers pointed to notably higher activity against Staphylococcus isolates (minimal inhibitory concentrations 0.75-1.5%) compared to tested gram-negative species (Escherichia coli and Pseudomonas aeruginosa). Antibiofilm activity against S. aureus, S. epidermidis, and P. aeruginosa determined in a crystal violet assay was promising (up to 69%), but monitoring of selected biofilm-related gene expression (pelA and algD) indicated the necessity of the involvement of a larger number of genes in the analysis in order to further establish the underlying mechanism. Although biocompatibility screening showed some cytotoxicity and genotoxicity in MTT and alkaline comet assays, respectively, it is important to note that active antioxidative and antibacterial/antibiofilm concentrations were non-cytotoxic and non-genotoxic in normal MRC-5 cells. These results encourage further composite improvements and investigation in order to adapt it for specific biomedical purposes.
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Affiliation(s)
- Nina Tomić
- Group for Biomedical Engineering and Nanobiotechnology, Institute of Technical Sciences of SASA, Kneza Mihaila 35/IV, 11000 Belgrade, Serbia; (N.T.); (N.F.)
| | - Magdalena M. Stevanović
- Group for Biomedical Engineering and Nanobiotechnology, Institute of Technical Sciences of SASA, Kneza Mihaila 35/IV, 11000 Belgrade, Serbia; (N.T.); (N.F.)
| | - Nenad Filipović
- Group for Biomedical Engineering and Nanobiotechnology, Institute of Technical Sciences of SASA, Kneza Mihaila 35/IV, 11000 Belgrade, Serbia; (N.T.); (N.F.)
| | - Tea Ganić
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (T.G.); (B.N.)
| | - Biljana Nikolić
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (T.G.); (B.N.)
| | - Ina Gajić
- Faculty of Medicine, Institute of Microbiology and Immunology, University of Belgrade, 11000 Belgrade, Serbia;
| | - Dragana Mitić Ćulafić
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (T.G.); (B.N.)
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9
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Gheorghita AA, Wozniak DJ, Parsek MR, Howell PL. Pseudomonas aeruginosa biofilm exopolysaccharides: assembly, function, and degradation. FEMS Microbiol Rev 2023; 47:fuad060. [PMID: 37884397 PMCID: PMC10644985 DOI: 10.1093/femsre/fuad060] [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: 04/21/2023] [Revised: 10/04/2023] [Accepted: 10/25/2023] [Indexed: 10/28/2023] Open
Abstract
The biofilm matrix is a fortress; sheltering bacteria in a protective and nourishing barrier that allows for growth and adaptation to various surroundings. A variety of different components are found within the matrix including water, lipids, proteins, extracellular DNA, RNA, membrane vesicles, phages, and exopolysaccharides. As part of its biofilm matrix, Pseudomonas aeruginosa is genetically capable of producing three chemically distinct exopolysaccharides - alginate, Pel, and Psl - each of which has a distinct role in biofilm formation and immune evasion during infection. The polymers are produced by highly conserved mechanisms of secretion, involving many proteins that span both the inner and outer bacterial membranes. Experimentally determined structures, predictive modelling of proteins whose structures are yet to be solved, and structural homology comparisons give us insight into the molecular mechanisms of these secretion systems, from polymer synthesis to modification and export. Here, we review recent advances that enhance our understanding of P. aeruginosa multiprotein exopolysaccharide biosynthetic complexes, and how the glycoside hydrolases/lyases within these systems have been commandeered for antimicrobial applications.
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Affiliation(s)
- Andreea A Gheorghita
- Program in Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Medical Science Building, 1 King's College Cir, Toronto, ON M5S 1A8, Canada
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University College of Medicine, 776 Biomedical Research Tower, 460 W 12th Ave, Columbus, OH 43210, United States
- Department of Microbiology, The Ohio State University College, Biological Sciences Bldg, 105, 484 W 12th Ave, Columbus, OH 43210, United States
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Health Sciences Bldg, 1705 NE Pacific St, Seattle, WA 98195-7735, United States
| | - P Lynne Howell
- Program in Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay St, Toronto, ON M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Medical Science Building, 1 King's College Cir, Toronto, ON M5S 1A8, Canada
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10
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Wang S, Zhao Y, Breslawec AP, Liang T, Deng Z, Kuperman LL, Yu Q. Strategy to combat biofilms: a focus on biofilm dispersal enzymes. NPJ Biofilms Microbiomes 2023; 9:63. [PMID: 37679355 PMCID: PMC10485009 DOI: 10.1038/s41522-023-00427-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 08/15/2023] [Indexed: 09/09/2023] Open
Abstract
Bacterial biofilms, which consist of three-dimensional extracellular polymeric substance (EPS), not only function as signaling networks, provide nutritional support, and facilitate surface adhesion, but also serve as a protective shield for the residing bacterial inhabitants against external stress, such as antibiotics, antimicrobials, and host immune responses. Biofilm-associated infections account for 65-80% of all human microbial infections that lead to serious mortality and morbidity. Tremendous effort has been spent to address the problem by developing biofilm-dispersing agents to discharge colonized microbial cells to a more vulnerable planktonic state. Here, we discuss the recent progress of enzymatic eradicating strategies against medical biofilms, with a focus on dispersal mechanisms. Particularly, we review three enzyme classes that have been extensively investigated, namely glycoside hydrolases, proteases, and deoxyribonucleases.
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Affiliation(s)
- Shaochi Wang
- Otorhinolaryngology Hospital, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
- Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yanteng Zhao
- Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Alexandra P Breslawec
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20740, USA
| | - Tingting Liang
- Key Laboratory of Natural Medicine and Immune-Engineering of Henan Province, Henan University Jinming Campus, 475004, Kaifeng, Henan, China
| | - Zhifen Deng
- Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Laura L Kuperman
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20740, USA.
- Mirimus Inc., 760 Parkside Avenue, Brooklyn, NY, 11226, USA.
| | - Qiuning Yu
- Otorhinolaryngology Hospital, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China.
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11
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Rodríguez-Suárez JM, Gershenson A, Onuh TU, Butler CS. The Heterogeneous Diffusion of Polystyrene Nanoparticles and the Effect on the Expression of Quorum-Sensing Genes and EPS Production as a Function of Particle Charge and Biofilm Age. ENVIRONMENTAL SCIENCE. NANO 2023; 10:2551-2565. [PMID: 37868332 PMCID: PMC10585598 DOI: 10.1039/d3en00219e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Biofilms are abundantly present in both natural and engineered environmental systems and will likely influence broader particle fate and transport phenomena. While some developed models describe the interactions between nanoparticles and biofilms, studies are only beginning to uncover the complexity of nanoparticle diffusion patterns. With the knowledge of the nanoparticle potential to influence bacterial processes, more systematic studies are needed to uncover the dynamics of bacteria-nanoparticle interactions. This study explored specific microbial responses to nanoparticles and the heterogeneity of nanoparticle diffusion. Pseudomonas aeruginosa biofilms (cultivated for 48 and 96 hours, representing early and late stages of development) were exposed to charged (aminated and carboxylated) polystyrene nanoparticles. With a combination of advanced fluorescence microscopy and real time quantitative PCR, we characterized the diffusion of polystyrene nanoparticles in P. aeruginosa biofilms and evaluated how biofilms respond to the presence of nanoparticles in terms of the expression of key EPS production-associated genes (pelA and rpsL) and quorum-sensing associated (lasR) genes. Our findings show that nanoparticle diffusion coefficients are independent of the particle surface charge only in mature biofilms and that the presence of nanoparticles influences bacterial gene expression. Independent of the particle's charge polystyrene nanoparticles down-regulated pelA in mature biofilms. By contrast, charge-specific responses were identified in lasR and rpsL gene expression. The targeted genes expression analysis and heterogeneous diffusion models demonstrate that particle charge influences nanoparticle mobility and provides significant insight into the intrinsic structural heterogeneity of P. aeruginosa biofilms. These findings suggest that biofilm maturity and particle charge are essential factors to consider when evaluating the transport of nanoparticles within a biofilm matrix.
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Affiliation(s)
- Joann M. Rodríguez-Suárez
- Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst MA 01003
| | - Anne Gershenson
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst MA 01003
| | - Timothy Umma Onuh
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst MA 01003
| | - Caitlyn S. Butler
- Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst MA 01003
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12
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Park S, Dingemans J, Sauer K. Manganese Acts as an Environmental Inhibitor of Pseudomonas aeruginosa Biofilm Development by Inducing Dispersion and Modulating c-di-GMP and Exopolysaccharide Production via RbdA. J Bacteriol 2023; 205:e0000323. [PMID: 37199658 PMCID: PMC10294637 DOI: 10.1128/jb.00003-23] [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: 01/03/2023] [Accepted: 04/27/2023] [Indexed: 05/19/2023] Open
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa causes chronic infections that involve multicellular aggregates called biofilms. Biofilm formation is modulated by the host environment and the presence of cues and/or signals, likely affecting the pool of the bacterial second messenger cyclic diguanylate monophosphate (c-di-GMP). The manganese ion Mn2+ is a divalent metal cation that is essential for pathogenic bacterial survival and replication during the infection in a host organism. In this study, we investigated how Mn2+ alters P. aeruginosa biofilm formation via the regulation of c-di-GMP levels. Exposure to Mn2+ was found to temporally enhance attachment but impair subsequent biofilm development, apparent by reduced biofilm biomass accumulation and lack of microcolony formation due to the induction of dispersion. Moreover, exposure to Mn2+ coincided with reduced production of the exopolysaccharides Psl and Pel, decreased transcriptional abundance of pel and psl, and decreased levels of c-di-GMP. To determine whether the effect of Mn2+ was linked to the activation of phosphodiesterases (PDEs), we screened several PDE mutants for Mn2+-dependent phenotypes (attachment and polysaccharide production) as well as PDE activity. The screen revealed that the PDE RbdA is activated by Mn2+ and is responsible for Mn2+-dependent attachment, inhibition of Psl production, and dispersion. Taken together, our findings suggest Mn2+ is an environmental inhibitor of P. aeruginosa biofilm development that acts through the PDE RbdA to modulate c-di-GMP levels, thereby impeding polysaccharide production and biofilm formation but enhancing dispersion. IMPORTANCE While diverse environmental conditions such as the availability of metal ions have been shown to affect biofilm development, little is known about the mechanism. Here, we demonstrate that Mn2+ affects Pseudomonas aeruginosa biofilm development by stimulating phosphodiesterase RbdA activity to reduce the signaling molecule c-di-GMP levels, thereby hindering polysaccharide production and biofilm formation but enhancing dispersion. Our findings demonstrate that Mn2+ acts as an environmental inhibitor of P. aeruginosa biofilms, further suggesting manganese to be a promising new antibiofilm factor.
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Affiliation(s)
- Soyoung Park
- Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA
| | - Jozef Dingemans
- Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA
| | - Karin Sauer
- Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
- Binghamton Biofilm Research Center, Binghamton University, Binghamton, New York, USA
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13
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Razvi E, DiFrancesco BR, Wasney GA, Morrison ZA, Tam J, Auger A, Baker P, Alnabelseya N, Rich JD, Sivarajah P, Whitfield GB, Harrison JJ, Melnyk RA, Nitz M, Howell PL. Small Molecule Inhibition of an Exopolysaccharide Modification Enzyme is a Viable Strategy To Block Pseudomonas aeruginosa Pel Biofilm Formation. Microbiol Spectr 2023; 11:e0029623. [PMID: 37098898 PMCID: PMC10269871 DOI: 10.1128/spectrum.00296-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/03/2023] [Indexed: 04/27/2023] Open
Abstract
Biosynthesis of the Pel exopolysaccharide in Pseudomonas aeruginosa requires all seven genes of the pelABCDEFG operon. The periplasmic modification enzyme PelA contains a C-terminal deacetylase domain that is necessary for Pel-dependent biofilm formation. Herein, we show that extracellular Pel is not produced by a P. aeruginosa PelA deacetylase mutant. This positions PelA deacetylase activity as an attractive target to prevent Pel-dependent biofilm formation. Using a high-throughput screen (n = 69,360), we identified 56 compounds that potentially inhibit PelA esterase activity, the first enzymatic step in the deacetylase reaction. A secondary biofilm inhibition assay identified methyl 2-(2-pyridinylmethylene) hydrazinecarbodithioate (SK-017154-O) as a specific Pel-dependent biofilm inhibitor. Structure-activity relationship studies identified the thiocarbazate as a necessary functional group and that the pyridyl ring could be replaced with a phenyl substituent (compound 1). Both SK-017154-O and compound 1 inhibit Pel-dependent biofilm formation in Bacillus cereus ATCC 10987, which has a predicted extracellular PelA deacetylase in its pel operon. Michaelis-Menten kinetics determined SK-017154-O to be a noncompetitive inhibitor of PelA, while compound 1 did not directly inhibit PelA esterase activity. Cytotoxicity assays using human lung fibroblast cells showed that compound 1 is less cytotoxic than SK-017154-O. This work provides proof of concept that biofilm exopolysaccharide modification enzymes are important for biofilm formation and can serve as useful antibiofilm targets. IMPORTANCE Present in more than 500 diverse Gram-negative and 900 Gram-positive organisms, the Pel polysaccharide is one of the most phylogenetically widespread biofilm matrix determinants found to date. Partial de-N-acetylation of this α-1,4 linked N-acetylgalactosamine polymer by the carbohydrate modification enzyme PelA is required for Pel-dependent biofilm formation in Pseudomonas aeruginosa and Bacillus cereus. Given this and our observation that extracellular Pel is not produced by a P. aeruginosa PelA deactylase mutant, we developed an enzyme-based high-throughput screen and identified methyl 2-(2-pyridinylmethylene) hydrazinecarbodithioate (SK-017154-O) and its phenyl derivative as specific Pel-dependent biofilm inhibitors. Michaelis-Menten kinetics revealed SK-017154-O is a noncompetitive inhibitor and that its noncytotoxic, phenyl derivative does not directly inhibit P. aeruginosa PelA esterase activity. We provide proof of concept that exopolysaccharide modification enzymes can be targeted with small molecule inhibitors to block Pel-dependent biofilm development in both Gram-negative and Gram-positive bacteria.
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Affiliation(s)
- Erum Razvi
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | | | - Gregory A. Wasney
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- The Structural & Biophysical Core Facility, The Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - John Tam
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Anick Auger
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- SPARC BioCentre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Perrin Baker
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Noor Alnabelseya
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jacquelyn D. Rich
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Piyanka Sivarajah
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gregory B. Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Joe J. Harrison
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Roman A. Melnyk
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Mark Nitz
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - P. Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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14
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Islam OK, Islam I, Saha O, Rahaman MM, Sultana M, Bockmühl DP, Hossain MA. Genomic variability correlates with biofilm phenotypes in multidrug resistant clinical isolates of Pseudomonas aeruginosa. Sci Rep 2023; 13:7867. [PMID: 37188866 DOI: 10.1038/s41598-023-35056-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 05/11/2023] [Indexed: 05/17/2023] Open
Abstract
The multifactorial nature of Pseudomonas aeruginosa biofilm development and genomic variabilities implicates its resistance to conventional antimicrobials and virulence. Therefore, genetic determinants need to be extensively studied to block the early steps of biofilm or already formed biofilms. In this study, a total of 20 multidrug resistant (MDR) clinical P. aeruginosa isolates were evaluated for their biofilm forming abilities and related genes. Of the isolates tested, all of them showed surface attachment tendencies in nutrient limiting conditions, and classified as strong (SBF = 45%), moderate (MBF = 30%) and weak (WBF = 25%) biofilm formers. Complete genome sequencing of representative strong (DMC-27b), moderate (DMC-20c) and weak biofilm former (DMC-30b) isolates was performed. Analysis of biofilm related genes in the sequenced genomes revealed that, 80 of the 88 biofilm related genes possess 98-100% sequence identity to the reference PAO1 strain. Complete and partial sequence data of LecB proteins from tested isolates indicate that isolates containing PA14-like LecB sequences produced strong biofilms. All of the 7 pel operon protein coding genes in weak biofilm former isolate 30b showed significant nucleotide sequence variation with other tested isolates, and their corresponding proteins are 99% identical with the pel operon proteins of PA7. Bioinformatics analyses identified divergent sequence and structural features that separate PA7 like pel operon proteins from reference PAO1-like pel operon. Congo red and pellicle forming assays revealed that the sequence and structure variations may have interfered with the Pel production pathway and resulted in impaired Pel production in isolate 30b that has a PA7 like pel operon. Expression analysis also showed that both pelB and lecB genes were about 5 to 6 folds upregulated after 24 h in SBF 27b in comparison with WBF 30b. Our findings indicate significant genomic divergence in biofilm related genes of P. aeruginosa strains that affect their biofilm phenotypes.
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Affiliation(s)
- Ovinu Kibria Islam
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
- Department of Microbiology, Jashore University of Science & Technology, Jashore, Bangladesh
| | - Israt Islam
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
- Department of Microbiology, Noakhali University of Science & Technology, Noakhali, Bangladesh
| | - Otun Saha
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
- Department of Microbiology, Noakhali University of Science & Technology, Noakhali, Bangladesh
| | | | - Munawar Sultana
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh
| | - Dirk P Bockmühl
- Faculty of Life Science, Rhine-Waal University of Applied Science, Kleve, Germany
| | - M Anwar Hossain
- Department of Microbiology, University of Dhaka, Dhaka, Bangladesh.
- Department of Microbiology, Jashore University of Science & Technology, Jashore, Bangladesh.
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15
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Chung J, Eisha S, Park S, Morris AJ, Martin I. How Three Self-Secreted Biofilm Exopolysaccharides of Pseudomonas aeruginosa, Psl, Pel, and Alginate, Can Each Be Exploited for Antibiotic Adjuvant Effects in Cystic Fibrosis Lung Infection. Int J Mol Sci 2023; 24:ijms24108709. [PMID: 37240055 DOI: 10.3390/ijms24108709] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 04/29/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
In cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a cause of increased morbidity and mortality, especially in patients for whom infection becomes chronic and there is reliance on long-term suppressive therapies. Current antimicrobials, though varied mechanistically and by mode of delivery, are inadequate not only due to their failure to eradicate infection but also because they do not halt the progression of lung function decline over time. One of the reasons for this failure is thought to be the biofilm mode of growth of P. aeruginosa, wherein self-secreted exopolysaccharides (EPSs) provide physical protection against antibiotics and an array of niches with resulting metabolic and phenotypic heterogeneity. The three biofilm-associated EPSs secreted by P. aeruginosa (alginate, Psl, and Pel) are each under investigation and are being exploited in ways that potentiate antibiotics. In this review, we describe the development and structure of P. aeruginosa biofilms before examining each EPS as a potential therapeutic target for combating pulmonary infection with P. aeruginosa in CF, with a particular focus on the current evidence for these emerging therapies and barriers to bringing these therapies into clinic.
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Affiliation(s)
- Jonathan Chung
- Department of Translational Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Shafinaz Eisha
- Department of Translational Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Subin Park
- Department of Translational Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Amanda J Morris
- Department of Translational Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Isaac Martin
- Department of Translational Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, 686 Bay Street, Toronto, ON M5G 0A4, Canada
- Division of Respiratory Medicine, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8, Canada
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16
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Stephens Z, Wilson LFL, Zimmer J. Diverse mechanisms of polysaccharide biosynthesis, assembly and secretion across kingdoms. Curr Opin Struct Biol 2023; 79:102564. [PMID: 36870276 DOI: 10.1016/j.sbi.2023.102564] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/16/2023] [Accepted: 01/28/2023] [Indexed: 03/06/2023]
Abstract
Polysaccharides are essential biopolymers produced in all kingdoms of life. On the cell surface, they represent versatile architectural components, forming protective capsules and coats, cell walls, or adhesives. Extracellular polysaccharide (EPS) biosynthesis mechanisms differ based on the cellular localization of polymer assembly. Some polysaccharides are first synthesized in the cytosol and then extruded by ATP powered transporters [1]. In other cases, the polymers are assembled outside the cell [2], synthesized and secreted in a single step [3], or deposited on the cell surface via vesicular trafficking [4]. This review focuses on recent insights into the biosynthesis, secretion, and assembly of EPS in microbes, plants and vertebrates. We focus on comparing the sites of biosynthesis, secretion mechanisms, and higher-order EPS assemblies.
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Affiliation(s)
- Zachery Stephens
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Louis F L Wilson
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Jochen Zimmer
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA.
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17
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Balducci E, Papi F, Capialbi DE, Del Bino L. Polysaccharides' Structures and Functions in Biofilm Architecture of Antimicrobial-Resistant (AMR) Pathogens. Int J Mol Sci 2023; 24:ijms24044030. [PMID: 36835442 PMCID: PMC9965654 DOI: 10.3390/ijms24044030] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/13/2023] [Accepted: 02/14/2023] [Indexed: 02/19/2023] Open
Abstract
Bacteria and fungi have developed resistance to the existing therapies such as antibiotics and antifungal drugs, and multiple mechanisms are mediating this resistance. Among these, the formation of an extracellular matrix embedding different bacterial cells, called biofilm, is an effective strategy through which bacterial and fungal cells are establishing a relationship in a unique environment. The biofilm provides them the possibility to transfer genes conferring resistance, to prevent them from desiccation and to impede the penetration of antibiotics or antifungal drugs. Biofilms are formed of several constituents including extracellular DNA, proteins and polysaccharides. Depending on the bacteria, different polysaccharides form the biofilm matrix in different microorganisms, some of them involved in the first stage of cells' attachment to surfaces and to each other, and some responsible for giving the biofilm structure resistance and stability. In this review, we describe the structure and the role of different polysaccharides in bacterial and fungal biofilms, we revise the analytical methods to characterize them quantitatively and qualitatively and finally we provide an overview of potential new antimicrobial therapies able to inhibit biofilm formation by targeting exopolysaccharides.
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Affiliation(s)
| | | | - Daniela Eloisa Capialbi
- GSK, 53100 Siena, Italy
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy
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18
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Razvi E, Whitfield GB, Reichhardt C, Dreifus JE, Willis AR, Gluscencova OB, Gloag ES, Awad TS, Rich JD, da Silva DP, Bond W, Le Mauff F, Sheppard DC, Hatton BD, Stoodley P, Reinke AW, Boulianne GL, Wozniak DJ, Harrison JJ, Parsek MR, Howell PL. Glycoside hydrolase processing of the Pel polysaccharide alters biofilm biomechanics and Pseudomonas aeruginosa virulence. NPJ Biofilms Microbiomes 2023; 9:7. [PMID: 36732330 PMCID: PMC9894940 DOI: 10.1038/s41522-023-00375-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Pel exopolysaccharide biosynthetic loci are phylogenetically widespread biofilm matrix determinants in bacteria. In Pseudomonas aeruginosa, Pel is crucial for cell-to-cell interactions and reducing susceptibility to antibiotic and mucolytic treatments. While genes encoding glycoside hydrolases have long been linked to biofilm exopolysaccharide biosynthesis, their physiological role in biofilm development is unclear. Here we demonstrate that the glycoside hydrolase activity of P. aeruginosa PelA decreases adherent biofilm biomass and is responsible for generating the low molecular weight secreted form of the Pel exopolysaccharide. We show that the generation of secreted Pel contributes to the biomechanical properties of the biofilm and decreases the virulence of P. aeruginosa in Caenorhabditis elegans and Drosophila melanogaster. Our results reveal that glycoside hydrolases found in exopolysaccharide biosynthetic systems can help shape the soft matter attributes of a biofilm and propose that secreted matrix components be referred to as matrix associated to better reflect their influence.
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Affiliation(s)
- Erum Razvi
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine Université de Montréal, Montréal, QC, Canada
| | - Courtney Reichhardt
- Department of Microbiology, University of Washington, Seattle, WA, USA
- Department of Chemistry, Washington University, St. Louis, MO, USA
| | - Julia E Dreifus
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Alexandra R Willis
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Oxana B Gluscencova
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Erin S Gloag
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Biomedical Sciences and Pathobiology, VA-MD College of Veterinary Medicine, Virginia Tech, VA, 24061, USA
| | - Tarek S Awad
- Department of Materials Science and Engineering, University of Toronto, Toronto, ON, Canada
| | - Jacquelyn D Rich
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Daniel Passos da Silva
- Department of Microbiology, University of Washington, Seattle, WA, USA
- BioVectra Inc. 11 Aviation, Charlottetown, PE, Canada
| | - Whitney Bond
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - François Le Mauff
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Infectious Disease and Immunity in Global Health, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada
| | - Donald C Sheppard
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada
- Infectious Disease and Immunity in Global Health, Research Institute of the McGill University Health Centre, Montreal, QC, Canada
- McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada
| | - Benjamin D Hatton
- Department of Materials Science and Engineering, University of Toronto, Toronto, ON, Canada
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Orthopedics, The Ohio State University, Columbus, OH, 43210, USA
- National Biofilm Innovation Centre (NBIC) and National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton, SO17 1BJ, UK
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
| | - Aaron W Reinke
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Gabrielle L Boulianne
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
| | - Joe J Harrison
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada.
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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19
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Seegers CII, Lee DJ, Zarnovican P, Kirsch SH, Müller R, Haselhorst T, Routier FH. Identification of Compounds Preventing A. fumigatus Biofilm Formation by Inhibition of the Galactosaminogalactan Deacetylase Agd3. Int J Mol Sci 2023; 24:ijms24031851. [PMID: 36768176 PMCID: PMC9915216 DOI: 10.3390/ijms24031851] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
The opportunistic fungus Aspergillus fumigatus causes a set of diseases ranging from allergy to lethal invasive mycosis. Within the human airways, A. fumigatus is embedded in a biofilm that forms not only a barrier against the host immune defense system, but also creates a physical barrier protecting the fungi from chemicals such as antifungal drugs. Novel therapeutic strategies aim at combining drugs that inhibit biofilm synthesis or disrupt existing biofilm with classical antimicrobials. One of the major constituents of A. fumigatus biofilm is the polysaccharide galactosaminogalactan (GAG) composed of α1,4-linked N-acetylgalactosamine, galactosamine, and galactose residues. GAG is synthesized on the cytosolic face of the plasma membrane and is extruded in the extracellular space, where it is partially deacetylated. The deacetylase Agd3 that mediates this last step is essential for the biofilm formation and full virulence of the fungus. In this work, a previously described enzyme-linked lectin assay, based on the adhesion of deacetylated GAG to negatively charged plates and quantification with biotinylated soybean agglutinin was adapted to screen microbial natural compounds, as well as compounds identified in in silico screening of drug libraries. Actinomycin X2, actinomycin D, rifaximin, and imatinib were shown to inhibit Agd3 activity in vitro. At a concentration of 100 µM, actinomycin D and imatinib showed a clear reduction in the biofilm biomass without affecting the fungal growth. Finally, imatinib reduced the virulence of A. fumigatus in a Galleria mellonella infection model in an Agd3-dependent manner.
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Affiliation(s)
- Carla I. I. Seegers
- Institute for Clinical Biochemistry, OE4340, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Danielle J. Lee
- Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland 4222, Australia
| | - Patricia Zarnovican
- Institute for Clinical Biochemistry, OE4340, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Susanne H. Kirsch
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research, Saarland University Campus, 66123 Saarbrücken, Germany
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research, Saarland University Campus, 66123 Saarbrücken, Germany
- German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, 38124 Braunschweig, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
| | - Thomas Haselhorst
- Institute for Glycomics, Griffith University, Gold Coast Campus, Queensland 4222, Australia
| | - Françoise H. Routier
- Institute for Clinical Biochemistry, OE4340, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
- Correspondence:
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20
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Role of Exopolysaccharides of Pseudomonas in Heavy Metal Removal and Other Remediation Strategies. Polymers (Basel) 2022; 14:polym14204253. [PMID: 36297831 PMCID: PMC9609410 DOI: 10.3390/polym14204253] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/30/2022] Open
Abstract
Pseudomonas biofilms have been studied intensively for several decades and research outcomes have been successfully implemented in various medical and agricultural applications. Research on biofilm synthesis and composition has also overlapped with the objectives of environmental sciences, since biofilm components show exceptional physicochemical properties applicable to remediation techniques. Especially, exopolysaccharides (ExPs) have been at the center of scientific interest, indicating their potential in solving the environmental issues of heavy metal land and water contamination via sorptive interactions and flocculation. Since exposure to heavy metal via contaminated water or soil poses an imminent risk to the environment and human health, ExPs provide an interesting and viable solution to this issue, alongside other effective and green remedial techniques (e.g., phytostabilization, implementation of biosolids, and biosorption using agricultural wastes) aiming to restore contaminated sites to their natural, pollution-free state, or to ameliorate the negative impact of heavy metals on the environment. Thus, we discuss the plausible role and performance of Pseudomonas ExPs in remediation techniques, aiming to provide the relevant available and comprehensive information on ExPs’ biosynthesis and their usage in heavy metal remediation or other environmental applications, such as wastewater treatment via bioflocculation and soil remediation.
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21
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Vandana, Das S. Genetic regulation, biosynthesis and applications of extracellular polysaccharides of the biofilm matrix of bacteria. Carbohydr Polym 2022; 291:119536. [DOI: 10.1016/j.carbpol.2022.119536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/22/2022] [Accepted: 04/22/2022] [Indexed: 11/02/2022]
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22
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Yin R, Cheng J, Wang J, Li P, Lin J. Treatment of Pseudomonas aeruginosa infectious biofilms: Challenges and strategies. Front Microbiol 2022; 13:955286. [PMID: 36090087 PMCID: PMC9459144 DOI: 10.3389/fmicb.2022.955286] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/09/2022] [Indexed: 01/10/2023] Open
Abstract
Pseudomonas aeruginosa, a Gram-negative bacterium, is one of the major pathogens implicated in human opportunistic infection and a common cause of clinically persistent infections such as cystic fibrosis, urinary tract infections, and burn infections. The main reason for the persistence of P. aeruginosa infections is due to the ability of P. aeruginosa to secrete extracellular polymeric substances such as exopolysaccharides, matrix proteins, and extracellular DNA during invasion. These substances adhere to and wrap around bacterial cells to form a biofilm. Biofilm formation leads to multiple antibiotic resistance in P. aeruginosa, posing a significant challenge to conventional single antibiotic therapeutic approaches. It has therefore become particularly important to develop anti-biofilm drugs. In recent years, a number of new alternative drugs have been developed to treat P. aeruginosa infectious biofilms, including antimicrobial peptides, quorum-sensing inhibitors, bacteriophage therapy, and antimicrobial photodynamic therapy. This article briefly introduces the process and regulation of P. aeruginosa biofilm formation and reviews several developed anti-biofilm treatment technologies to provide new directions for the treatment of P. aeruginosa biofilm infection.
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23
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Preclinical Evaluation of Recombinant Microbial Glycoside Hydrolases as Antibiofilm Agents in Acute Pulmonary Pseudomonas aeruginosa Infection. Antimicrob Agents Chemother 2022; 66:e0005222. [PMID: 35862738 PMCID: PMC9380554 DOI: 10.1128/aac.00052-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The bacterium Pseudomonas aeruginosa can colonize the airways of patients with chronic lung disease. Within the lung, P. aeruginosa forms biofilms that can enhance resistance to antibiotics and immune defenses. P. aeruginosa biofilm formation is dependent on the secretion of matrix exopolysaccharides, including Pel and Psl. In this study, recombinant glycoside hydrolases (GHs) that degrade Pel and Psl were evaluated alone and in combination with antibiotics in a mouse model of P. aeruginosa infection. Intratracheal GH administration was well tolerated by mice. Pharmacokinetic analysis revealed that, although GHs have short half-lives, administration of two GHs in combination resulted in increased GH persistence. Combining GH prophylaxis and treatment with the antibiotic ciprofloxacin resulted in greater reduction in pulmonary bacterial burden than that with either agent alone. This study lays the foundation for further exploration of GH therapy in bacterial infections.
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24
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Ma LZ, Wang D, Liu Y, Zhang Z, Wozniak DJ. Regulation of Biofilm Exopolysaccharide Biosynthesis and Degradation in Pseudomonas aeruginosa. Annu Rev Microbiol 2022; 76:413-433. [DOI: 10.1146/annurev-micro-041320-111355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbial communities enmeshed in a matrix of macromolecules, termed as biofilms, are the natural setting of bacteria. Exopolysaccharide is a critical matrix component of biofilms. Here, we focus on biofilm matrix exopolysaccharides in Pseudomonas aeruginosa. This opportunistic pathogen can adapt to a wide range of environments and can form biofilms or aggregates in a variety of surfaces or environments, such as the lungs of people with cystic fibrosis, catheters, wounds, and contact lenses. The ability to synthesize multiple exopolysaccharides is one of the advantages that facilitate bacterial survival in different environments. P. aeruginosa can produce several exopolysaccharides, including alginate, Psl, Pel, and lipopolysaccharide. In this review, we highlight the roles of each exopolysaccharide in P. aeruginosa biofilm development and how bacteria coordinate the biosynthesis of multiple exopolysaccharides and bacterial motility. In addition, we present advances in antibiofilm strategies targeting matrix exopolysaccharides, with a focus on glycoside hydrolases. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Luyan Z. Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Di Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yiwei Liu
- Department of Microbial Infection and Immunity and Department of Microbiology, Ohio State University, Columbus, Ohio, USA
| | - Zhenyu Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Daniel J. Wozniak
- Department of Microbial Infection and Immunity and Department of Microbiology, Ohio State University, Columbus, Ohio, USA
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25
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Sarvari R, Naghili B, Agbolaghi S, Abbaspoor S, Bannazadeh Baghi H, Poortahmasebi V, Sadrmohammadi M, Hosseini M. Organic/polymeric antibiofilm coatings for surface modification of medical devices. INT J POLYM MATER PO 2022. [DOI: 10.1080/00914037.2022.2066668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Raana Sarvari
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behrooz Naghili
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Samira Agbolaghi
- Chemical Engineering Department, Faculty of Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran
| | | | - Hossein Bannazadeh Baghi
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Vahdat Poortahmasebi
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Bacteriology and Virology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mehdi Sadrmohammadi
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Maryam Hosseini
- Chemical Engineering Department, Faculty of Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran
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26
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The c-di-GMP Phosphodiesterase PipA (PA0285) Regulates Autoaggregation and Pf4 Bacteriophage Production in Pseudomonas aeruginosa PAO1. Appl Environ Microbiol 2022; 88:e0003922. [PMID: 35638845 DOI: 10.1128/aem.00039-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In Pseudomonas aeruginosa PAO1, 41 genes encode proteins predicted to be involved in the production or degradation of c-di-GMP, a ubiquitous secondary messenger that regulates a variety of physiological behaviors closely related to biofilm and aggregate formation. Despite extensive effort, the entire picture of this important signaling network is still unclear, with one-third of these proteins remaining uncharacterized. Here, we show that the deletion of pipA, which produces a protein containing two PAS domains upstream of a GGDEF-EAL tandem, significantly increased the intracellular c-di-GMP level and promoted the formation of aggregates both on surfaces and in planktonic cultures. However, this regulatory effect was not contributed by either of the two classic pathways modulating biofilm formation, exopolysaccharide (EPS) overproduction or motility inhibition. Transcriptome sequencing (RNA-Seq) data revealed that the expression levels of 361 genes were significantly altered in a ΔpipA mutant strain compared to the wild type (WT), indicating the critical role of PipA in PAO1. The most remarkably downregulated genes were located on the Pf4 bacteriophage gene cluster, which corresponded to a 2-log reduction in the Pf4 phage production in the ΔpipA mutant. The sizes of aggregates in ΔpipA cultures were affected by exogenously added Pf4 phage in a concentration-dependent manner, suggesting the quantity of phage plays a part in regulating the formation of aggregates. Further analysis demonstrated that PipA is highly conserved across 83 P. aeruginosa strains. Our work therefore for the first time showed that a c-di-GMP phosphodiesterase can regulate bacteriophage production and provided new insights into the relationship between bacteriophage and bacterial aggregation. IMPORTANCE The c-di-GMP signaling pathways in P. aeruginosa are highly organized and well coordinated, with different diguanylate cyclases and phosphodiesterases playing distinct roles in a complex network. Understanding the function of each enzyme and the underlying regulatory mechanisms not only is crucial for revealing how bacteria decide the transition between motile and sessile lifestyles, but also greatly facilitates the development of new antibiofilm strategies. This work identified bacteriophage production as a novel phenotypic output controlled transcriptionally by a phosphodiesterase, PipA. Further analysis suggested that the quantity of phage may be important in regulating autoaggregation, as either a lack of phage or overproduction was associated with higher levels of aggregation. Our study therefore extended the scope of c-di-GMP-controlled phenotypes and discovered a potential signaling circuit that can be target for biofilm treatment.
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27
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Le Mauff F, Razvi E, Reichhardt C, Sivarajah P, Parsek MR, Howell PL, Sheppard DC. The Pel polysaccharide is predominantly composed of a dimeric repeat of α-1,4 linked galactosamine and N-acetylgalactosamine. Commun Biol 2022; 5:502. [PMID: 35618750 PMCID: PMC9135694 DOI: 10.1038/s42003-022-03453-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 05/06/2022] [Indexed: 12/20/2022] Open
Abstract
The genetic capacity to synthesize the biofilm matrix exopolysaccharide Pel is widespread among Gram-negative and Gram-positive bacteria. However, its exact chemical structure has been challenging to determine. Using a Pseudomonas aeruginosa strain engineered to overproduce Pel, improvements to the isolation procedure, and selective hydrolysis with the glycoside hydrolase PelAh, we demonstrate that Pel is a partially de-N-acetylated linear polymer of α-1,4-N-acetylgalactosamine comprised predominantly of dimeric repeats of galactosamine and N-acetylgalactosamine. The structure of the Pel exopolysaccharide from Pseudomonas aeruginosa is fully characterized.
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Affiliation(s)
- François Le Mauff
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada.,Infectious Disease in Global Health Program, McGill University Health Centre, Montreal, QC, Canada.,McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada
| | - Erum Razvi
- Program in Molecular Medicine, Research Institute The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Courtney Reichhardt
- Department of Microbiology, University of Washington, Seattle, WA, USA.,Department of Chemistry, Washington University, St. Louis, MO, 63130, USA
| | - Piyanka Sivarajah
- Program in Molecular Medicine, Research Institute The Hospital for Sick Children, Toronto, ON, Canada
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - P Lynne Howell
- Program in Molecular Medicine, Research Institute The Hospital for Sick Children, Toronto, ON, Canada. .,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
| | - Donald C Sheppard
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, QC, Canada. .,Infectious Disease in Global Health Program, McGill University Health Centre, Montreal, QC, Canada. .,McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, QC, Canada.
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28
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Co-Operative Biofilm Interactions between Aspergillus fumigatus and Pseudomonas aeruginosa through Secreted Galactosaminogalactan Exopolysaccharide. J Fungi (Basel) 2022; 8:jof8040336. [PMID: 35448567 PMCID: PMC9030451 DOI: 10.3390/jof8040336] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 01/27/2023] Open
Abstract
The mold Aspergillus fumigatus and bacterium Pseudomonas aeruginosa form biofilms in the airways of individuals with cystic fibrosis. Biofilm formation by A. fumigatus depends on the self-produced cationic exopolysaccharide galactosaminogalactan (GAG), while P. aeruginosa biofilms can contain the cationic exopolysaccharide Pel. GAG and Pel are rendered cationic by deacetylation mediated by either the secreted deacetylase Agd3 (A. fumigatus) or the periplasmic deacetylase PelA (P. aeruginosa). Given the similarities between these polymers, the potential for biofilm interactions between these organisms were investigated. P. aeruginosa were observed to adhere to A. fumigatus hyphae in a GAG-dependent manner and to GAG-coated coverslips of A. fumigatus biofilms. In biofilm adherence assays, incubation of P. aeruginosa with A. fumigatus culture supernatants containing de-N-acetylated GAG augmented the formation of adherent P. aeruginosa biofilms, increasing protection against killing by the antibiotic colistin. Fluorescence microscopy demonstrated incorporation of GAG within P. aeruginosa biofilms, suggesting that GAG can serve as an alternate biofilm exopolysaccharide for this bacterium. In contrast, Pel-containing bacterial culture supernatants only augmented the formation of adherent A. fumigatus biofilms when antifungal inhibitory molecules were removed. This study demonstrates biofilm interaction via exopolysaccharides as a potential mechanism of co-operation between these organisms in chronic lung disease.
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29
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Aflakian F, Rad M, Hashemitabar G, Lagzian M, Ramezani M. Design and assessment of novel synthetic peptides to inhibit quorum sensing-dependent biofilm formation in Pseudomonas aeruginosa. BIOFOULING 2022; 38:131-146. [PMID: 35067121 DOI: 10.1080/08927014.2022.2028280] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 01/01/2022] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Pseudomonas aeruginosa is one of the most common biofilm-producing bacteria, often leading to long-term and chronic infections. The LasR regulator protein acts as the central regulator of the quorum sensing (QS) system and coordinates the expression of some virulence and biofilm genes. In this study, novel peptides (WSF, FASK, YDVD) were designed for binding to the domain of the transcriptional activator of the LasR protein and interfere with LasR in the QS system of P. aeruginosa. The effects of these peptides on biofilm production, expression of biofilm-related genes (AlgC, PslA, PelA), and growth of planktonic P. aeruginosa were investigated. All three peptides inhibited the growth of P. aeruginosa planktonic cells at 1600 µg ml-1 and exhibited anti-biofilm effects at sub-inhibitory concentrations (800 µg ml-1). Measurements of the mRNA levels of biofilm-related genes at sub-inhibitory concentrations of the designed peptides showed a significant decrease.
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Affiliation(s)
- Fatemeh Aflakian
- Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mehrnaz Rad
- Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Gholamreza Hashemitabar
- Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Milad Lagzian
- Department of Biology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran
| | - Mohammad Ramezani
- Pharmaceutical Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran
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30
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Fischer S, Klockgether J, Gonzalez Sorribes M, Dorda M, Wiehlmann L, Tümmler B. Sequence diversity of the Pseudomonas aeruginosa population in loci that undergo microevolution in cystic fibrosis airways. Access Microbiol 2022; 3:000286. [PMID: 35024551 PMCID: PMC8749138 DOI: 10.1099/acmi.0.000286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 10/04/2021] [Indexed: 12/23/2022] Open
Abstract
Five hundred and thirty-four unrelated Pseudomonas aeruginosa isolates from inanimate habitats, patients with cystic fibrosis (CF) and other human infections were sequenced in 19 genes that had been identified previously as the hot spots of genomic within-host evolution in serial isolates from 12 CF lungs. Amplicon sequencing confirmed a significantly higher sequence diversity of the 19 loci in P. aeruginosa isolates from CF patients compared to those from other habitats, but this overrepresentation was mainly due to the larger share of synonymous substitutions. Correspondingly, non-synonymous substitutions were either rare (gltT, lepA, ptsP) or benign (nuoL, fleR, pelF) in some loci. Other loci, however, showed an accumulation of non-neutral coding variants. Strains from the CF habitat were often mutated at evolutionarily conserved positions in the elements of stringent response (RelA, SpoT), LPS (PagL), polyamine transport (SpuE, SpuF) and alginate biosynthesis (AlgG, AlgU). The strongest skew towards the CF lung habitat was seen for amino acid sequence variants in AlgG that clustered in the carbohydrate-binding/sugar hydrolysis domain. The master regulators of quorum sensing lasR and rhlR were frequent targets for coding variants in isolates from chronic and acute human infections. Unique variants in lasR showed strong evidence of positive selection indicated by d N/d S values of ~4. The pelA gene that encodes a multidomain enzyme involved in both the formation and dispersion of Pel biofilms carried the highest number of single-nucleotide variants among the 19 genes and was the only gene with a higher frequency of missense mutations in P. aeruginosa strains from non-CF habitats than in isolates from CF airways. PelA protein variants are widely distributed in the P. aeruginosa population. In conclusion, coding variants in a subset of the examined loci are indeed characteristic for the adaptation of P. aeruginosa to the CF airways, but for other loci the elevated mutation rate is more indicative of infections in human habitats (lasR, rhlR) or global diversifying selection (pelA).
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Affiliation(s)
- Sebastian Fischer
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Jens Klockgether
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany
| | - Marina Gonzalez Sorribes
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Marie Dorda
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Research Core Unit Genomics, Hannover Medical School, Hannover, Germany
| | - Lutz Wiehlmann
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Research Core Unit Genomics, Hannover Medical School, Hannover, Germany
| | - Burkhard Tümmler
- Clinical Research Group 'Molecular Pathology of Cystic Fibrosis', Department for Paediatric Pneumology, Allergology and Neonatology, Hannover Medical School, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), German Center for Lung Research, Hannover Medical School, Germany
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31
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Gheorghita AA, Wolfram F, Whitfield GB, Jacobs HM, Pfoh R, Wong SSY, Guitor AK, Goodyear MC, Berezuk AM, Khursigara CM, Parsek MR, Howell PL. The Pseudomonas aeruginosa homeostasis enzyme AlgL clears the periplasmic space of accumulated alginate during polymer biosynthesis. J Biol Chem 2022; 298:101560. [PMID: 34990713 PMCID: PMC8829089 DOI: 10.1016/j.jbc.2021.101560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 11/24/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen and a leading cause of chronic infection in the lungs of individuals with cystic fibrosis. After colonization, P. aeruginosa often undergoes a phenotypic conversion to mucoidy, characterized by overproduction of the alginate exopolysaccharide. This conversion is correlated with poorer patient prognoses. The majority of genes required for alginate synthesis, including the alginate lyase, algL, are located in a single operon. Previous investigations of AlgL have resulted in several divergent hypotheses regarding the protein’s role in alginate production. To address these discrepancies, we determined the structure of AlgL and, using multiple sequence alignments, identified key active site residues involved in alginate binding and catalysis. In vitro enzymatic analysis of active site mutants highlights R249 and Y256 as key residues required for alginate lyase activity. In a genetically engineered P. aeruginosa strain where alginate biosynthesis is under arabinose control, we found that AlgL is required for cell viability and maintaining membrane integrity during alginate production. We demonstrate that AlgL functions as a homeostasis enzyme to clear the periplasmic space of accumulated polymer. Constitutive expression of the AlgU/T sigma factor mitigates the effects of an algL deletion during alginate production, suggesting that an AlgU/T-regulated protein or proteins can compensate for an algL deletion. Together, our study demonstrates the role of AlgL in alginate biosynthesis, explains the discrepancies observed previously across other P. aeruginosa ΔalgL genetic backgrounds, and clarifies the existing divergent data regarding the function of AlgL as an alginate degrading enzyme.
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Affiliation(s)
- Andreea A Gheorghita
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Francis Wolfram
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Holly M Jacobs
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington, USA
| | - Roland Pfoh
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Steven S Y Wong
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Allison K Guitor
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Mara C Goodyear
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Alison M Berezuk
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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Secor PR, Michaels LA, Bublitz DC, Jennings LK, Singh PK. The Depletion Mechanism Actuates Bacterial Aggregation by Exopolysaccharides and Determines Species Distribution & Composition in Bacterial Aggregates. Front Cell Infect Microbiol 2022; 12:869736. [PMID: 35782109 PMCID: PMC9243289 DOI: 10.3389/fcimb.2022.869736] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
Bacteria in natural environments and infections are often found in cell aggregates suspended in polymer-rich solutions, and aggregation can promote bacterial survival and stress resistance. One aggregation mechanism, called depletion aggregation, is driven by physical forces between bacteria and high concentrations of polymers in the environment rather than bacterial activity per se. As such, bacteria aggregated by the depletion mechanism will disperse when polymer concentrations fall unless other adhesion mechanisms supervene. Here we investigated whether the depletion mechanism can actuate the aggregating effects of Pseudomonas aeruginosa exopolysaccharides for suspended (i.e. not surface attached) bacteria, and how depletion affects bacterial inter-species interactions. We found that cells overexpressing the exopolysaccharides Pel and Psl remained aggregated after short periods of depletion aggregation whereas wild-type and mucoid P. aeruginosa did not. In co-culture, depletion aggregation had contrasting effects on P. aeruginosa's interactions with coccus- and rod-shaped bacteria. Depletion caused S. aureus (cocci) and P. aeruginosa (rods) to segregate from each other and S. aureus to resist secreted P. aeruginosa antimicrobial factors resulting in species co-existence. In contrast, depletion aggregation caused P. aeruginosa and Burkholderia sp. (both rods) to intermix, enhancing type VI secretion inhibition of Burkholderia by P. aeruginosa, leading to P. aeruginosa dominance. These results show that in addition to being a primary cause of aggregation in polymer-rich suspensions, physical forces inherent to the depletion mechanism can promote aggregation by some self-produced exopolysaccharides and determine species distribution and composition of bacterial communities.
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Affiliation(s)
- Patrick R Secor
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Lia A Michaels
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - DeAnna C Bublitz
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Laura K Jennings
- Division of Biological Sciences, University of Montana, Missoula, MT, United States
| | - Pradeep K Singh
- Department of Microbiology, University of Washington, Seattle, WA, United States
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Thorn CR, Howell PL, Wozniak DJ, Prestidge CA, Thomas N. Enhancing the therapeutic use of biofilm-dispersing enzymes with smart drug delivery systems. Adv Drug Deliv Rev 2021; 179:113916. [PMID: 34371086 DOI: 10.1016/j.addr.2021.113916] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/27/2021] [Accepted: 08/02/2021] [Indexed: 12/18/2022]
Abstract
Biofilm-dispersing enzymes degrade the extracellular polymeric matrix surrounding bacterial biofilms, disperse the microbial community and increase their susceptibility to antibiotics and immune cells. Challenges for the clinical translation of biofilm-dispersing enzymes involve their susceptibility to denaturation, degradation, and clearance upon administration in vivo. Drug delivery systems aim to overcome these limitations through encapsulation, stabilization and protection from the exterior environment, thereby maintaining the enzymatic activity. Smart drug delivery systems offer target specificity, releasing payloads at the site of infection while minimizing unnecessary systemic exposure. This review highlights critical advances of biofilm-dispersing enzymes as a novel therapeutic approach for biofilm-associated infections. We explore how smart, bio-responsive delivery systems overcome the limiting factors of biofilm-dispersing enzymes and summarize the key systems designed. This review will guide future developments, focusing on utilizing selective and specific therapies in a targeted fashion to meet the unmet therapeutic needs of biofilm infections.
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Affiliation(s)
- Chelsea R Thorn
- University of South Australia, Clinical and Health Sciences, North Tce, Adelaide, SA 5000, Australia; The Basil Hetzel Institute for Translational Health Research, Woodville, SA 5011, Australia; ARC Centre for Excellence in Bio-Nano Science and Technology, Adelaide, SA 5000, Australia; Biofilm Test Facility, Cancer Research Institute, University of South Australia, North Tce, Adelaide, SA 5000, Australia
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Daniel J Wozniak
- Departments of Microbial Infection and Immunity, Ohio State University, Columbus, OH 43210, USA
| | - Clive A Prestidge
- University of South Australia, Clinical and Health Sciences, North Tce, Adelaide, SA 5000, Australia; ARC Centre for Excellence in Bio-Nano Science and Technology, Adelaide, SA 5000, Australia
| | - Nicky Thomas
- University of South Australia, Clinical and Health Sciences, North Tce, Adelaide, SA 5000, Australia; The Basil Hetzel Institute for Translational Health Research, Woodville, SA 5011, Australia; ARC Centre for Excellence in Bio-Nano Science and Technology, Adelaide, SA 5000, Australia; Biofilm Test Facility, Cancer Research Institute, University of South Australia, North Tce, Adelaide, SA 5000, Australia.
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Preclinical Evaluation of Recombinant Microbial Glycoside Hydrolases in the Prevention of Experimental Invasive Aspergillosis. mBio 2021; 12:e0244621. [PMID: 34579578 PMCID: PMC8546845 DOI: 10.1128/mbio.02446-21] [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] [Indexed: 02/05/2023] Open
Abstract
Aspergillus fumigatus is a ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses. Aspergillus biofilm formation requires the production of a cationic matrix exopolysaccharide, galactosaminogalactan (GAG). In this study, recombinant glycoside hydrolases (GH)s that degrade GAG were evaluated as antifungal agents in a mouse model of invasive aspergillosis. Intratracheal GH administration was well tolerated by mice. Pharmacokinetic analysis revealed that although GHs have short half-lives, GH prophylaxis resulted in reduced fungal burden in leukopenic mice and improved survival in neutropenic mice, possibly through augmenting pulmonary neutrophil recruitment. Combining GH prophylaxis with posaconazole treatment resulted in a greater reduction in fungal burden than either agent alone. This study lays the foundation for further exploration of GH therapy in invasive fungal infections. IMPORTANCE The biofilm-forming mold Aspergillus fumigatus is a common causative agent of invasive fungal airway disease in patients with a compromised immune system or chronic airway disease. Treatment of A. fumigatus infection is limited by the few available antifungals to which fungal resistance is becoming increasingly common. The high mortality rate of A. fumigatus-related infection reflects a need for the development of novel therapeutic strategies. The fungal biofilm matrix is in part composed of the adhesive exopolysaccharide galactosaminogalactan, against which antifungals are less effective. Previously, we demonstrated antibiofilm activity with recombinant forms of the glycoside hydrolase enzymes that are involved in galactosaminogalactan biosynthesis. In this study, prophylaxis with glycoside hydrolases alone or in combination with the antifungal posaconazole in a mouse model of experimental aspergillosis improved outcomes. This study offers insight into the therapeutic potential of combining biofilm disruptive agents to leverage the activity of currently available antifungals.
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Poulin MB, Kuperman LL. Regulation of Biofilm Exopolysaccharide Production by Cyclic Di-Guanosine Monophosphate. Front Microbiol 2021; 12:730980. [PMID: 34566936 PMCID: PMC8461298 DOI: 10.3389/fmicb.2021.730980] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/09/2021] [Indexed: 11/25/2022] Open
Abstract
Many bacterial species in nature possess the ability to transition into a sessile lifestyle and aggregate into cohesive colonies, known as biofilms. Within a biofilm, bacterial cells are encapsulated within an extracellular polymeric substance (EPS) comprised of polysaccharides, proteins, nucleic acids, lipids, and other small molecules. The transition from planktonic growth to the biofilm lifecycle provides numerous benefits to bacteria, such as facilitating adherence to abiotic surfaces, evasion of a host immune system, and resistance to common antibiotics. As a result, biofilm-forming bacteria contribute to 65% of infections in humans, and substantially increase the energy and time required for treatment and recovery. Several biofilm specific exopolysaccharides, including cellulose, alginate, Pel polysaccharide, and poly-N-acetylglucosamine (PNAG), have been shown to play an important role in bacterial biofilm formation and their production is strongly correlated with pathogenicity and virulence. In many bacteria the biosynthetic machineries required for assembly of these exopolysaccharides are regulated by common signaling molecules, with the second messenger cyclic di-guanosine monophosphate (c-di-GMP) playing an especially important role in the post-translational activation of exopolysaccharide biosynthesis. Research on treatments of antibiotic-resistant and biofilm-forming bacteria through direct targeting of c-di-GMP signaling has shown promise, including peptide-based treatments that sequester intracellular c-di-GMP. In this review, we will examine the direct role c-di-GMP plays in the biosynthesis and export of biofilm exopolysaccharides with a focus on the mechanism of post-translational activation of these pathways, as well as describe novel approaches to inhibit biofilm formation through direct targeting of c-di-GMP.
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Affiliation(s)
- Myles B Poulin
- Department of Chemistry and Biochemistry, University of Maryland, College Park, College Park, MD, United States
| | - Laura L Kuperman
- Department of Chemistry and Biochemistry, University of Maryland, College Park, College Park, MD, United States
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Montes-Osuna N, Gómez-Lama Cabanás C, Valverde-Corredor A, Berendsen RL, Prieto P, Mercado-Blanco J. Assessing the Involvement of Selected Phenotypes of Pseudomonas simiae PICF7 in Olive Root Colonization and Biological Control of Verticillium dahliae. PLANTS 2021; 10:plants10020412. [PMID: 33672351 PMCID: PMC7926765 DOI: 10.3390/plants10020412] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/16/2021] [Accepted: 02/19/2021] [Indexed: 12/19/2022]
Abstract
Pseudomonas simiae PICF7 is an indigenous inhabitant of the olive (Olea europaea L.) rhizosphere/root endosphere and an effective biocontrol agent against Verticillium wilt of olive (VWO), caused by the soil-borne fungus Verticillium dahliae. This study aimed to evaluate the potential involvement of selected phenotypes of strain PICF7 in root colonization ability and VWO biocontrol. Therefore, a random transposon-insertion mutant bank of P. simiae PICF7 was screened for the loss of phenotypes likely involved in rhizosphere/soil persistence (copper resistance), root colonization (biofilm formation) and plant growth promotion (phytase activity). Transposon insertions in genes putatively coding for the transcriptional regulator CusR or the chemotaxis protein CheV were found to affect copper resistance, whereas an insertion in fleQ gene putatively encoding a flagellar regulatory protein hampered the ability to form a biofilm. However, these mutants displayed the same antagonistic effect against V. dahliae as the parental strain. Remarkably, two mutants impaired in biofilm formation were never found inside olive roots, whereas their ability to colonize the root exterior and to control VWO remained unaffected. Endophytic colonization of olive roots was unaltered in mutants impaired in copper resistance and phytase production. Results demonstrated that the phenotypes studied were irrelevant for VWO biocontrol.
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Affiliation(s)
- Nuria Montes-Osuna
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal s/n, Campus “Alameda del Obispo”, 14004 Córdoba, Spain; (N.M.-O.); (C.G.-L.C.); (A.V.-C.)
| | - Carmen Gómez-Lama Cabanás
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal s/n, Campus “Alameda del Obispo”, 14004 Córdoba, Spain; (N.M.-O.); (C.G.-L.C.); (A.V.-C.)
| | - Antonio Valverde-Corredor
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal s/n, Campus “Alameda del Obispo”, 14004 Córdoba, Spain; (N.M.-O.); (C.G.-L.C.); (A.V.-C.)
| | - Roeland L. Berendsen
- Plant–Microbe Interactions, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands;
| | - Pilar Prieto
- Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal s/n, Campus “Alameda del Obispo”, 14004 Córdoba, Spain;
| | - Jesús Mercado-Blanco
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal s/n, Campus “Alameda del Obispo”, 14004 Córdoba, Spain; (N.M.-O.); (C.G.-L.C.); (A.V.-C.)
- Correspondence:
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Jennings LK, Dreifus JE, Reichhardt C, Storek KM, Secor PR, Wozniak DJ, Hisert KB, Parsek MR. Pseudomonas aeruginosa aggregates in cystic fibrosis sputum produce exopolysaccharides that likely impede current therapies. Cell Rep 2021; 34:108782. [PMID: 33626358 PMCID: PMC7958924 DOI: 10.1016/j.celrep.2021.108782] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/18/2021] [Accepted: 02/02/2021] [Indexed: 12/17/2022] Open
Abstract
In cystic fibrosis (CF) airways, Pseudomonas aeruginosa forms cellular aggregates called biofilms that are thought to contribute to chronic infection. To form aggregates, P. aeruginosa can use different mechanisms, each with its own pathogenic implications. However, how they form in vivo is controversial and unclear. One mechanism involves a bacterially produced extracellular matrix that holds the aggregates together. Pel and Psl exopolysaccharides are structural and protective components of this matrix. We develop an immunohistochemical method to visualize Pel and Psl in CF sputum. We demonstrate that both exopolysaccharides are expressed in the CF airways and that the morphology of aggregates is consistent with an exopolysaccharide-dependent aggregation mechanism. We reason that the cationic exopolysaccharide Pel may interact with some of the abundant anionic host polymers in sputum. We show that Pel binds extracellular DNA (eDNA) and that this interaction likely impacts current therapies by increasing antimicrobial tolerance and protecting eDNA from digestion.
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Affiliation(s)
- Laura K Jennings
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Julia E Dreifus
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Courtney Reichhardt
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Kelly M Storek
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Patrick R Secor
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Daniel J Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA; Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA; Infectious Disease Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Katherine B Hisert
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
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38
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Whitfield GB, Howell PL. The Matrix Revisited: Opening Night for the Pel Polysaccharide Across Eubacterial Kingdoms. Microbiol Insights 2021; 14:1178636120988588. [PMID: 33642867 PMCID: PMC7890745 DOI: 10.1177/1178636120988588] [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: 11/24/2020] [Accepted: 12/16/2020] [Indexed: 01/29/2023] Open
Abstract
Bacteria synthesize and export adhesive macromolecules to enable biofilm formation. These macromolecules, collectively called the biofilm matrix, are structurally varied and often unique to specific bacterial species or subspecies. This heterogeneity in matrix utilization makes it difficult to facilitate direct comparison between biofilm formation mechanisms of different bacterial species. Despite this, some matrix components, in particular the polysaccharides poly-β-1,6-N-acetyl-glucosamine (PNAG) and bacterial cellulose, are utilized by many Gram-negative species for biofilm formation. However, there is a very narrow distribution of these components across Gram-positive organisms, whose biofilm matrix determinants remain largely undiscovered. We found that a genetic locus required for the production of a biofilm matrix component of P. aeruginosa, the Pel polysaccharide, is widespread in Gram-negative bacteria and that there is a variant form of this cluster present in many Gram-positive bacterial species. We demonstrated that this locus is required for biofilm formation by Bacillus cereus ATCC 10987, produces a polysaccharide that is similar to Pel, and is post-translationally regulated by cyclic-3′,5′-dimeric-guanosine monophosphate (c-di-GMP) in a manner identical to P. aeruginosa. However, while the proposed mechanism for Pel production appears remarkably similar between B. cereus and P. aeruginosa, we identified several key differences between Gram-negative and Gram-positive Pel biosynthetic components in other monoderms. In particular, 4 different architectural subtypes of the c-di-GMP-binding component PelD were identified, including 1 found only in Streptococci that has entirely lost the c-di-GMP recognition domain. These observations highlight how existing multi-component bacterial machines can be subtly tweaked to adapt to the unique physiology and regulatory mechanisms of Gram-positive organisms. Collectively, our analyses suggest that the Pel biosynthetic locus is one of the most phylogenetically widespread biofilm matrix determinants in bacteria, and that its mechanism of production and regulation is extraordinarily conserved across the majority of organisms that possess it.
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Affiliation(s)
- Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, ON, Canada.,Département de Microbiologie, Infectiologie, et Immunologie, Université de Montréal, QC, Canada
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, ON, Canada
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Pseudomonas aeruginosa Uses c-di-GMP Phosphodiesterases RmcA and MorA To Regulate Biofilm Maintenance. mBio 2021; 12:mBio.03384-20. [PMID: 33531388 PMCID: PMC7858071 DOI: 10.1128/mbio.03384-20] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent advances in our understanding of c-di-GMP signaling have provided key insights into the regulation of biofilms. Despite an improved understanding of how biofilms initially form, the processes that facilitate the long-term maintenance of these multicellular communities remain opaque. While the early stages of biofilm formation have been well characterized, less is known about the requirements for Pseudomonas aeruginosa to maintain a mature biofilm. We utilized a P. aeruginosa-phage interaction to identify rmcA and morA, two genes which encode bis-(3′,5′)-cyclic dimeric GMP (c-di-GMP)-degrading phosphodiesterases (PDEs) and are important for the regulation of biofilm maintenance. Deletion of these genes initially results in an elevated biofilm phenotype characterized by increased production of c-di-GMP, Pel polysaccharide, and/or biofilm biomass. In contrast to the wild-type strain, these mutants were unable to maintain the biofilm when exposed to carbon-limited conditions. The susceptibility to nutrient limitation, as well as subsequent loss of biofilm viability of these mutants, was phenotypically reproduced with a stringent response mutant (ΔrelA ΔspoT), indicating that the ΔrmcA and ΔmorA mutants may be unable to appropriately respond to nutrient limitation. Genetic and biochemical data indicate that RmcA and MorA physically interact with the Pel biosynthesis machinery, supporting a model whereby unregulated Pel biosynthesis contributes to the death of the ΔrmcA and ΔmorA mutant strains in an established biofilm under nutrient limitation. These findings provide evidence that c-di-GMP-mediated regulation is required for mature biofilms of P. aeruginosa to effectively respond to changing availability of nutrients. Furthermore, the PDEs involved in biofilm maintenance are distinct from those required for establishing a biofilm, suggesting that a wide variety of c-di-GMP metabolizing enzymes in organisms such as P. aeruginosa allows for discrete control over the formation, maintenance or dispersion of biofilms.
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40
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Thi MTT, Wibowo D, Rehm BH. Pseudomonas aeruginosa Biofilms. Int J Mol Sci 2020; 21:ijms21228671. [PMID: 33212950 PMCID: PMC7698413 DOI: 10.3390/ijms21228671] [Citation(s) in RCA: 293] [Impact Index Per Article: 73.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen causing devastating acute and chronic infections in individuals with compromised immune systems. Its highly notorious persistence in clinical settings is attributed to its ability to form antibiotic-resistant biofilms. Biofilm is an architecture built mostly by autogenic extracellular polymeric substances which function as a scaffold to encase the bacteria together on surfaces, and to protect them from environmental stresses, impedes phagocytosis and thereby conferring the capacity for colonization and long-term persistence. Here we review the current knowledge on P. aeruginosa biofilms, its development stages, and molecular mechanisms of invasion and persistence conferred by biofilms. Explosive cell lysis within bacterial biofilm to produce essential communal materials, and interspecies biofilms of P. aeruginosa and commensal Streptococcus which impedes P. aeruginosa virulence and possibly improves disease conditions will also be discussed. Recent research on diagnostics of P. aeruginosa infections will be investigated. Finally, therapeutic strategies for the treatment of P. aeruginosa biofilms along with their advantages and limitations will be compiled.
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Marmont LS, Whitfield GB, Pfoh R, Williams RJ, Randall TE, Ostaszewski A, Razvi E, Groves RA, Robinson H, Nitz M, Parsek MR, Lewis IA, Whitney JC, Harrison JJ, Howell PL. PelX is a UDP- N-acetylglucosamine C4-epimerase involved in Pel polysaccharide-dependent biofilm formation. J Biol Chem 2020; 295:11949-11962. [PMID: 32601062 PMCID: PMC7443510 DOI: 10.1074/jbc.ra120.014555] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/24/2020] [Indexed: 12/15/2022] Open
Abstract
Pel is a GalNAc-rich bacterial polysaccharide that contributes to the structure and function of Pseudomonas aeruginosa biofilms. The pelABCDEFG operon is highly conserved among diverse bacterial species, and Pel may therefore be a widespread biofilm determinant. Previous annotation of pel gene clusters has helped us identify an additional gene, pelX, that is present adjacent to pelABCDEFG in >100 different bacterial species. The pelX gene is predicted to encode a member of the short-chain dehydrogenase/reductase (SDR) superfamily, but its potential role in Pel-dependent biofilm formation is unknown. Herein, we have used Pseudomonas protegens Pf-5 as a model to elucidate PelX function as Pseudomonas aeruginosa lacks a pelX homologue in its pel gene cluster. We found that P. protegens forms Pel-dependent biofilms; however, despite expression of pelX under these conditions, biofilm formation was unaffected in a ΔpelX strain. This observation led us to identify a pelX paralogue, PFL_5533, which we designate here PgnE, that appears to be functionally redundant to pelX In line with this, a ΔpelX ΔpgnE double mutant was substantially impaired in its ability to form Pel-dependent biofilms. To understand the molecular basis for this observation, we determined the structure of PelX to 2.1 Å resolution. The structure revealed that PelX resembles UDP-GlcNAc C4-epimerases. Using 1H NMR analysis, we show that PelX catalyzes the epimerization between UDP-GlcNAc and UDP-GalNAc. Our results indicate that Pel-dependent biofilm formation requires a UDP-GlcNAc C4-epimerase that generates the UDP-GalNAc precursors required by the Pel synthase machinery for polymer production.
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Affiliation(s)
- Lindsey S Marmont
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Roland Pfoh
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rohan J Williams
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Trevor E Randall
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | | | - Erum Razvi
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Ryan A Groves
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Howard Robinson
- Photon Science Division, Brookhaven National Laboratory, Upton, New York, USA
| | - Mark Nitz
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Matthew R Parsek
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Ian A Lewis
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - John C Whitney
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Joe J Harrison
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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Spectroscopic Study on Pseudomonas Aeruginosa Biofilm in the Presence of the Aptamer-DNA Scaffolded Silver Nanoclusters. Molecules 2020; 25:molecules25163631. [PMID: 32785202 PMCID: PMC7464845 DOI: 10.3390/molecules25163631] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/27/2020] [Accepted: 08/06/2020] [Indexed: 11/17/2022] Open
Abstract
We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect to the control sample. The importance of the secondary structure of the aptamer DNA in targeting, successfully binding with the cells and delivering the Ag-NC, is evidenced by the decrease in disorder strength (Ld) of the Ag-NC treated samples compared to the untreated PA cells, which showed the abundance of higher Ld in the PWS studies. The higher Ld value attributed to the higher mass density fluctuations and the formation of biofilm. We envision this study to open a new avenue in using a powerful optical microscopic technique like PWS in detection, and DNA aptamer enclosed silver nanoclusters to prevent biofilms for opportunist pathogens like Pseudomonas aeruginosa.
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Szymańska M, Karakulska J, Sobolewski P, Kowalska U, Grygorcewicz B, Böttcher D, Bornscheuer UT, Drozd R. Glycoside hydrolase (PelA h) immobilization prevents Pseudomonas aeruginosa biofilm formation on cellulose-based wound dressing. Carbohydr Polym 2020; 246:116625. [PMID: 32747262 DOI: 10.1016/j.carbpol.2020.116625] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 05/30/2020] [Accepted: 06/08/2020] [Indexed: 12/13/2022]
Abstract
Bacterial cellulose (BC) is recognized as a wound dressing material well-suited for chronic wounds; however, it has no intrinsic antimicrobial activity. Further, the formation of biofilms can limit the effectiveness of the pre-saturation of BC with antimicrobial agents. Here, to hinder biofilm formation by P. aeruginosa, we immobilized the hydrolytic domain of PelA (a glycohydrolase involved in the synthesis of biofilm polysaccharide Pel) on the surface of BC. The immobilization of 32.35 ± 1.05 mg PelAh per g BC membrane resulted in an eight-fold higher P. aeruginosa cell detachment from BC membrane, indicating reduced biofilm matrix stability. Further, 1D and 2D infrared spectroscopy analysis indicated systematic reduction of polysaccharide biofilm elements, confirming the specificity of immobilized PelAh. Importantly, BC-PelAh was not cytotoxic towards L929 fibroblast cells. Thus, we conclude that PelAh can be used in BC wound dressings for safe and specific protection against biofilm formation by P. aeruginosa.
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Affiliation(s)
- Magdalena Szymańska
- Department of Microbiology and Biotechnology, Faculty of Biotechnology and Animal Husbandry, West Pomeranian University of Technology in Szczecin, 45 Piastow Avenue, 71-311, Szczecin, Poland
| | - Jolanta Karakulska
- Department of Microbiology and Biotechnology, Faculty of Biotechnology and Animal Husbandry, West Pomeranian University of Technology in Szczecin, 45 Piastow Avenue, 71-311, Szczecin, Poland
| | - Peter Sobolewski
- Department of Polymer and Biomaterials Science, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, 45 Piastów Avenue, 71-311, Szczecin, Poland
| | - Urszula Kowalska
- Center of Bioimmobilisation and Innovative Packaging Materials, Faculty of Food Science and Fisheries, West Pomeranian University of Technology in Szczecin, 35 Klemensa Janickiego Str., 71-270, Szczecin, Poland
| | - Bartłomiej Grygorcewicz
- Department of Laboratory Medicine, Chair of Microbiology, Immunology and Laboratory Medicine, Pomeranian Medical University in Szczecin, 72 Powstańców Wielkopolskich Str., 70-111, Szczecin, Poland
| | - Dominique Böttcher
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487, Greifswald, Germany
| | - Uwe T Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487, Greifswald, Germany
| | - Radosław Drozd
- Department of Microbiology and Biotechnology, Faculty of Biotechnology and Animal Husbandry, West Pomeranian University of Technology in Szczecin, 45 Piastow Avenue, 71-311, Szczecin, Poland.
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Badal D, Jayarani AV, Kollaran MA, Kumar A, Singh V. Pseudomonas aeruginosa biofilm formation on endotracheal tubes requires multiple two-component systems. J Med Microbiol 2020; 69:906-919. [PMID: 32459613 DOI: 10.1099/jmm.0.001199] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Introduction. Indwelling medical devices such as endotracheal tubes (ETTs), urinary catheters, vascular access devices, tracheostomies and feeding tubes are often associated with hospital-acquired infections. Bacterial biofilm formed on the ETTs in intubated patients is a significant risk factor associated with ventilator-associated pneumonia. Pseudomonas aeruginosa is one of the four frequently encountered bacteria responsible for causing pneumonia, and the biofilm formation on ETTs. However, understanding of biofilm formation on ETT and interventions to prevent biofilm remains lagging. The ability to sense and adapt to external cues contributes to their success. Thus, the biofilm formation is likely to be influenced by the two-component systems (TCSs) that are composed of a membrane-associated sensor kinase and an intracellular response regulator.Aim. This study aims to establish an in vitro method to analyse the P. aeruginosa biofilm formation on ETTs, and identify the TCSs that contribute to this process.Methodology. In total, 112 P. aeruginosa PA14 TCS mutants were tested for their ability to form biofilm on ETTs, their effect on quorum sensing (QS) and motility.Results. Out of 112 TCS mutants studied, 56 had altered biofilm biomass on ETTs. Although the biofilm formation on ETTs is QS-dependent, none of the 56 loci controlled quorum signal. Of these, 18 novel TCSs specific to ETT biofilm were identified, namely, AauS, AgtS, ColR, CopS, CprR, NasT, KdpD, ParS, PmrB, PprA, PvrS, RcsC, PA14_11120, PA14_32580, PA14_45880, PA14_49420, PA14_52240, PA14_70790. The set of 56 included the GacS network, TCS proteins involved in fimbriae synthesis, TCS proteins involved in antimicrobial peptide resistance, and surface-sensing. Additionally, several of the TCS-encoding genes involved in biofilm formation on ETTs were found to be linked to flagellum-dependent swimming motility.Conclusions. Our study established an in vitro method for studying P. aeruginosa biofilm formation on the ETT surfaces. We also identified novel ETT-specific TCSs that could serve as targets to prevent biofilm formation on indwelling devices frequently used in clinical settings.
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Affiliation(s)
- Divakar Badal
- Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Abhijith Vimal Jayarani
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Mohammed Ameen Kollaran
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Aloke Kumar
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA.,Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
| | - Varsha Singh
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, INDIA.,Department of Biosystems Sciences and Engineering, Indian Institute of Science, Bangalore, Karnataka, INDIA
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Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation. Nat Commun 2020; 11:2450. [PMID: 32415073 PMCID: PMC7229062 DOI: 10.1038/s41467-020-16144-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 04/16/2020] [Indexed: 01/14/2023] Open
Abstract
The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Deletion of a gene encoding a putative deacetylase, Agd3, leads to defects in GAG deacetylation, biofilm formation, and virulence. Here, we show that Agd3 deacetylates GAG in a metal-dependent manner, and is the founding member of carbohydrate esterase family CE18. The active site is formed by four catalytic motifs that are essential for activity. The structure of Agd3 includes an elongated substrate-binding cleft formed by a carbohydrate binding module (CBM) that is the founding member of CBM family 87. Agd3 homologues are encoded in previously unidentified putative bacterial exopolysaccharide biosynthetic operons and in other fungal genomes.
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Whitfield GB, Marmont LS, Bundalovic-Torma C, Razvi E, Roach EJ, Khursigara CM, Parkinson J, Howell PL. Discovery and characterization of a Gram-positive Pel polysaccharide biosynthetic gene cluster. PLoS Pathog 2020; 16:e1008281. [PMID: 32236137 PMCID: PMC7112168 DOI: 10.1371/journal.ppat.1008281] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 12/11/2019] [Indexed: 12/14/2022] Open
Abstract
Our understanding of the biofilm matrix components utilized by Gram-positive bacteria, and the signalling pathways that regulate their production are largely unknown. In a companion study, we developed a computational pipeline for the unbiased identification of homologous bacterial operons and applied this algorithm to the analysis of synthase-dependent exopolysaccharide biosynthetic systems. Here, we explore the finding that many species of Gram-positive bacteria have operons with similarity to the Pseudomonas aeruginosa pel locus. Our characterization of the pelDEADAFG operon from Bacillus cereus ATCC 10987, presented herein, demonstrates that this locus is required for biofilm formation and produces a polysaccharide structurally similar to Pel. We show that the degenerate GGDEF domain of the B. cereus PelD ortholog binds cyclic-3',5'-dimeric guanosine monophosphate (c-di-GMP), and that this binding is required for biofilm formation. Finally, we identify a diguanylate cyclase, CdgF, and a c-di-GMP phosphodiesterase, CdgE, that reciprocally regulate the production of Pel. The discovery of this novel c-di-GMP regulatory circuit significantly contributes to our limited understanding of c-di-GMP signalling in Gram-positive organisms. Furthermore, conservation of the core pelDEADAFG locus amongst many species of bacilli, clostridia, streptococci, and actinobacteria suggests that Pel may be a common biofilm matrix component in many Gram-positive bacteria.
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Affiliation(s)
- Gregory B Whitfield
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Lindsey S Marmont
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Cedoljub Bundalovic-Torma
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Erum Razvi
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Elyse J Roach
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - John Parkinson
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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47
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Pel Polysaccharide Biosynthesis Requires an Inner Membrane Complex Comprised of PelD, PelE, PelF, and PelG. J Bacteriol 2020; 202:JB.00684-19. [PMID: 31988082 DOI: 10.1128/jb.00684-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 01/17/2020] [Indexed: 12/31/2022] Open
Abstract
The Pel polysaccharide is a structural component of the extracellular matrix of Pseudomonas aeruginosa biofilms. Recent analyses suggest that Pel production proceeds via a synthase-dependent polysaccharide secretion pathway, which in Gram-negative bacteria is defined by an outer membrane β-barrel porin, a periplasmic tetratricopeptide repeat-containing scaffold protein, and an inner membrane-embedded synthase. Polymerization is catalyzed by the glycosyltransferase domain of the synthase component of these systems, which is allosterically regulated by cyclic 3',5'-dimeric GMP (c-di-GMP). However, while the outer membrane and periplasmic components of the Pel system have been characterized, the inner membrane complex required for Pel polymerization has yet to be defined. To address this, we examined over 500 pel gene clusters from diverse species of Proteobacteria This analysis identified an invariant set of four syntenic genes, three of which, pelD, pelE, and pelG, are predicted to reside within the inner membrane, while the fourth, pelF, encodes a glycosyltransferase domain. Using a combination of gene deletion analysis, subcellular fractionation, coimmunoprecipitation, and bacterial two-hybrid assays, we provide evidence for the existence of an inner membrane complex of PelD, PelE, and PelG. Furthermore, we show that this complex interacts with PelF in order to facilitate its localization to the inner membrane. Mutations that abolish c-di-GMP binding to the known receptor domain of PelD had no effect on complex formation, suggesting that c-di-GMP binding stimulates Pel production through quaternary structural rearrangements. Together, these data provide the first experimental evidence of an inner membrane complex involved in Pel polysaccharide production.IMPORTANCE The exopolysaccharide Pel plays an important role in bacterial cell-cell interactions, surface adhesion, and protection against certain antibiotics. We identified invariant pelDEFG gene clusters in over 500 diverse proteobacterial species. Using Pseudomonas aeruginosa, we demonstrate that PelD, PelE, PelF, and PelG form a complex at the inner membrane and propose that this complex represents the previously unidentified Pel polysaccharide synthase, which is responsible for Pel polymerization and transport across the cytoplasmic membrane. We show that the formation of this complex is independent of cyclic 3',5'-dimeric GMP (c-di-GMP) binding to the receptor PelD. Collectively, these data establish the widespread Pel apparatus as a member of the synthase-dependent pathway of polysaccharide biosynthetic systems and broaden the architectural diversity of already-established bacterial polysaccharide synthases.
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Untethering and Degradation of the Polysaccharide Matrix Are Essential Steps in the Dispersion Response of Pseudomonas aeruginosa Biofilms. J Bacteriol 2020; 202:JB.00575-19. [PMID: 31712279 DOI: 10.1128/jb.00575-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 10/31/2019] [Indexed: 01/08/2023] Open
Abstract
Biofilms are multicellular aggregates of bacteria that are encased in an extracellular matrix. The biofilm matrix of Pseudomonas aeruginosa PAO1 is composed of eDNA, proteins, and the polysaccharides Pel and Psl. This matrix is thought to be degraded during dispersion to liberate cells from the biofilms, with dispersion being apparent not only by single cells escaping from the biofilm but also leaving behind eroded or hollowed-out biofilm. However, little is known of the factors involved in matrix degradation. Here, we focused on the glycoside hydrolases PelA and PslG. We demonstrate that induction of pelA but not pslG expression resulted in dispersion. As Psl is tethered to the matrix adhesin CdrA, we furthermore explored the role of CdrA in dispersion. cdrA mutant biofilms were hyperdispersive, while lapG mutant biofilms were impaired in dispersion in response to glutamate and nitric oxide, indicating the presence of the surface-associated matrix protein CdrA impedes the dispersion response. In turn, insertional inactivation of cdrA enabled pslG-induced dispersion. Lowering of the intracellular c-di-GMP level via induction of PA2133 encoding a phosphodiesterase was not sufficient to induce dispersion by wild-type strains and strains overexpressing pslG, indicating that pslG-induced dispersion is independent of c-di-GMP modulation and, likely, LapG.IMPORTANCE Pseudomonas aeruginosa forms multicellular aggregates or biofilms encased in a matrix. We show for the first time here that dispersion by P. aeruginosa requires the endogenous expression of pelA and pslG, leading to the degradation of both Pel and Psl polysaccharides, with PslG-induced dispersion being CdrA dependent. The findings suggested that endogenously induced Psl degradation is a sequential process, initiated by untethering of CdrA-bound Psl or CdrA-dependent cell interactions to enable Psl degradation and ultimately, dispersion. Untethering likely involves CdrA release in a manner independent of c-di-GMP modulation and thus LapG. Our findings not only provide insight into matrix degrading factors contributing to dispersion but also identify key steps in the degradation of structural components of the P. aeruginosa biofilm matrix.
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Le Mauff F, Bamford NC, Alnabelseya N, Zhang Y, Baker P, Robinson H, Codée JDC, Howell PL, Sheppard DC. Molecular mechanism of Aspergillus fumigatus biofilm disruption by fungal and bacterial glycoside hydrolases. J Biol Chem 2019; 294:10760-10772. [PMID: 31167793 DOI: 10.1074/jbc.ra119.008511] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 05/31/2019] [Indexed: 12/30/2022] Open
Abstract
During infection, the fungal pathogen Aspergillus fumigatus forms biofilms that enhance its resistance to antimicrobials and host defenses. An integral component of the biofilm matrix is galactosaminogalactan (GAG), a cationic polymer of α-1,4-linked galactose and partially deacetylated N-acetylgalactosamine (GalNAc). Recent studies have shown that recombinant hydrolase domains from Sph3, an A. fumigatus glycoside hydrolase involved in GAG synthesis, and PelA, a multifunctional protein from Pseudomonas aeruginosa involved in Pel polysaccharide biosynthesis, can degrade GAG, disrupt A. fumigatus biofilms, and attenuate fungal virulence in a mouse model of invasive aspergillosis. The molecular mechanisms by which these enzymes disrupt biofilms have not been defined. We hypothesized that the hydrolase domains of Sph3 and PelA (Sph3h and PelAh, respectively) share structural and functional similarities given their ability to degrade GAG and disrupt A. fumigatus biofilms. MALDI-TOF enzymatic fingerprinting and NMR experiments revealed that both proteins are retaining endo-α-1,4-N-acetylgalactosaminidases with a minimal substrate size of seven residues. The crystal structure of PelAh was solved to 1.54 Å and structure alignment to Sph3h revealed that the enzymes share similar catalytic site residues. However, differences in the substrate-binding clefts result in distinct enzyme-substrate interactions. PelAh hydrolyzed partially deacetylated substrates better than Sph3h, a finding that agrees well with PelAh's highly electronegative binding cleft versus the neutral surface present in Sph3h Our insight into PelAh's structure and function necessitate the creation of a new glycoside hydrolase family, GH166, whose structural and mechanistic features, along with those of GH135 (Sph3), are reported here.
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Affiliation(s)
- François Le Mauff
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, H3A 2B4 Quebec, Canada,; Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, H4A 3J1 Quebec, Canada,; McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, H3A 1Y2 Quebec, Canada
| | - Natalie C Bamford
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 1X8 Ontario, Canada,; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, M5S 1A8 Ontario, Canada
| | - Noor Alnabelseya
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 1X8 Ontario, Canada,; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, M5S 1A8 Ontario, Canada
| | - Yongzhen Zhang
- Leiden Institute of Chemistry, Leiden University, 2300RA Leiden, The Netherlands, and
| | - Perrin Baker
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 1X8 Ontario, Canada
| | - Howard Robinson
- Photon Science Division, Brookhaven National Laboratory, Upton, New York 11973-5000
| | - Jeroen D C Codée
- Leiden Institute of Chemistry, Leiden University, 2300RA Leiden, The Netherlands, and
| | - P Lynne Howell
- Program in Molecular Medicine, The Hospital for Sick Children, Toronto, M5G 1X8 Ontario, Canada,; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, M5S 1A8 Ontario, Canada,.
| | - Donald C Sheppard
- Department of Microbiology and Immunology, Faculty of Medicine, McGill University, Montreal, H3A 2B4 Quebec, Canada,; Infectious Disease and Immunity in Global Health, Research Institute of McGill University Health Center, Montreal, H4A 3J1 Quebec, Canada,; McGill Interdisciplinary Initiative in Infection and Immunity, Montreal, H3A 1Y2 Quebec, Canada,.
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50
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Treatment with the Pseudomonas aeruginosa Glycoside Hydrolase PslG Combats Wound Infection by Improving Antibiotic Efficacy and Host Innate Immune Activity. Antimicrob Agents Chemother 2019; 63:AAC.00234-19. [PMID: 30988141 DOI: 10.1128/aac.00234-19] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 04/04/2019] [Indexed: 12/25/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic, nosocomial bacterial pathogen that forms persistent infections due to the formation of protective communities, known as biofilms. Once the biofilm is formed, the bacteria embedded within it are recalcitrant to antimicrobial treatment and host immune defenses. Moreover, the presence of biofilms in wounds is correlated with chronic infection and delayed healing. The current standard of care for chronic wound infections typically involves physical disruption of the biofilm via debridement and subsequent antimicrobial treatment. The glycoside hydrolases PelAh and PslGh have been demonstrated in vitro to disrupt biofilm integrity through degradation of the key biofilm matrix exopolysaccharides Pel and Psl, respectively. Herein, we demonstrate that PslGh hydrolase therapy is a promising strategy for controlling P. aeruginosa wound infections. Hydrolase treatment of P. aeruginosa biofilms resulted in increased antibiotic efficacy and penetration into the biofilm. PslGh treatment of P. aeruginosa biofilms also improved innate immune activity leading to greater complement deposition, neutrophil phagocytosis, and neutrophil reactive oxygen species production. Furthermore, when P. aeruginosa-infected wounds were treated with a combination of PslGh and tobramycin, we observed an additive effect leading to greater bacterial clearance than treatments of tobramycin or PslGh alone. This study demonstrates that PelAh and PslGh have promising therapeutic potential and that PslGh may aid in the treatment of P. aeruginosa wound infections.
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