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Kermani AA, Biboy J, Vollmer D, Vollmer W. Outer membrane-anchoring enables LpoB to regulate peptidoglycan synthesis rate. Cell Surf 2022; 8:100086. [PMID: 36304570 PMCID: PMC9593243 DOI: 10.1016/j.tcsw.2022.100086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/19/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
Peptidoglycan (PG) is an essential component of the cell envelope in most bacteria, responsible for maintaining the shape of the cell and protecting the cell from environmental stresses. The growth of the PG layer during cell elongation and division is facilitated by the coordinated activities of PG synthases and hydrolases. PG synthases are regulated from inside the cell by components of the elongasome and divisome complexes driven by the cytoskeletal proteins MreB and FtsZ. In Escherichia coli the PG synthases PBP1A and PBP1B require the activation by outer membrane (OM)-anchored lipoproteins LpoA and LpoB, respectively. These have an elongated structure and are capable to span the periplasm to reach their cognate, cytoplasmic membrane (CM)-anchored PG synthase through the PG layer. Presumably, the Lpo proteins activate the PBPs at sites where the PG mesh is stretched or defective, resulting in coupling of PG synthase activation with cell growth or PG repair. Here we investigated the importance of OM-anchoring on the function of Lpo proteins in regulating PG synthesis in response to environmental stresses. We investigated the effects of an artificially CM-tethered LpoB on cell morphology and PG synthesis. Our results indicate that mis-localization of LpoB affects the growth and morphology of cells in high osmolarity growth medium, and PG synthesis rate upon an osmotic upshift.
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Jalalvand F, Su YC, Manat G, Chernobrovkin A, Kadari M, Jonsson S, Janousková M, Rutishauser D, Semsey S, Løbner-Olesen A, Sandblad L, Flärdh K, Mengin-Lecreulx D, Zubarev RA, Riesbeck K. Protein domain-dependent vesiculation of Lipoprotein A, a protein that is important in cell wall synthesis and fitness of the human respiratory pathogen Haemophilus influenzae. Front Cell Infect Microbiol 2022; 12:984955. [PMID: 36275016 PMCID: PMC9585305 DOI: 10.3389/fcimb.2022.984955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022] Open
Abstract
The human pathogen Haemophilus influenzae causes respiratory tract infections and is commonly associated with prolonged carriage in patients with chronic obstructive pulmonary disease. Production of outer membrane vesicles (OMVs) is a ubiquitous phenomenon observed in Gram-negative bacteria including H. influenzae. OMVs play an important role in various interactions with the human host; from neutralization of antibodies and complement activation to spread of antimicrobial resistance. Upon vesiculation certain proteins are found in OMVs and some proteins are retained at the cell membrane. The mechanism for this phenomenon is not fully elucidated. We employed mass spectrometry to study vesiculation and the fate of proteins in the outer membrane. Functional groups of proteins were differentially distributed on the cell surface and in OMVs. Despite its supposedly periplasmic and outer membrane location, we found that the peptidoglycan synthase-activator Lipoprotein A (LpoA) was accumulated in OMVs relative to membrane fractions. A mutant devoid of LpoA lost its fitness as revealed by growth and electron microscopy. Furthermore, high-pressure liquid chromatography disclosed a lower concentration (55%) of peptidoglycan in the LpoA-deficient H. influenzae compared to the parent wild type bacterium. Using an LpoA-mNeonGreen fusion protein and fluorescence microscopy, we observed that LpoA was enriched in “foci” in the cell envelope, and further located in the septum during cell division. To define the fate of LpoA, C-terminally truncated LpoA-variants were constructed, and we found that the LpoA C-terminal domain promoted optimal transportation to the OMVs as revealed by flow cytometry. Taken together, our study highlights the importance of LpoA for H. influenzae peptidoglycan biogenesis and provides novel insights into cell wall integrity and OMV production.
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Affiliation(s)
- Farshid Jalalvand
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Yu-Ching Su
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Guillaume Manat
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Alexey Chernobrovkin
- Physiological Chemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Mahendar Kadari
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Sandra Jonsson
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Martina Janousková
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
| | - Dorothea Rutishauser
- Physiological Chemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Szabolcs Semsey
- Centre for Bacterial Stress Response and Persistence, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Anders Løbner-Olesen
- Centre for Bacterial Stress Response and Persistence, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Klas Flärdh
- Department of Biology, Lund University, Lund, Sweden
| | - Dominique Mengin-Lecreulx
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Roman A. Zubarev
- Physiological Chemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Kristian Riesbeck
- Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden
- *Correspondence: Kristian Riesbeck,
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Abstract
Bacteria surround their cell membrane with a net-like peptidoglycan layer, called sacculus, to protect the cell from bursting and maintain its cell shape. Sacculus growth during elongation and cell division is mediated by dynamic and transient multiprotein complexes, the elongasome and divisome, respectively. In this Review we present our current understanding of how peptidoglycan synthases are regulated by multiple and specific interactions with cell morphogenesis proteins that are linked to a dynamic cytoskeletal protein, either the actin-like MreB or the tubulin-like FtsZ. Several peptidoglycan synthases and hydrolases require activation by outer-membrane-anchored lipoproteins. We also discuss how bacteria achieve robust cell wall growth under different conditions and stresses by maintaining multiple peptidoglycan enzymes and regulators as well as different peptidoglycan growth mechanisms, and we present the emerging role of LD-transpeptidases in peptidoglycan remodelling.
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Caveney NA, Egan AJF, Ayala I, Laguri C, Robb CS, Breukink E, Vollmer W, Strynadka NCJ, Simorre JP. Structure of the Peptidoglycan Synthase Activator LpoP in Pseudomonas aeruginosa. Structure 2020; 28:643-650.e5. [PMID: 32320673 PMCID: PMC7267771 DOI: 10.1016/j.str.2020.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/15/2020] [Accepted: 03/24/2020] [Indexed: 12/23/2022]
Abstract
Peptidoglycan (PG) is an essential component of the bacterial cell wall and is assembled from a lipid II precursor by glycosyltransferase and transpeptidase reactions catalyzed in particular by bifunctional class A penicillin-binding proteins (aPBPs). In the major clinical pathogen Pseudomonas aeruginosa, PBP1B is anchored within the cytoplasmic membrane but regulated by a bespoke outer membrane-localized lipoprotein known as LpoP. Here, we report the structure of LpoP, showing an extended N-terminal, flexible tether followed by a well-ordered C-terminal tandem-tetratricopeptide repeat domain. We show that LpoP stimulates both PBP1B transpeptidase and glycosyltransferase activities in vitro and interacts directly via its C terminus globular domain with the central UB2H domain of PBP1B. Contrary to the situation in E. coli, P. aeruginosa CpoB does not regulate PBP1B/LpoP in vitro. We propose a mechanism that helps to underscore similarities and differences in class A PBP activation across Gram-negative bacteria. Structural organization of LpoP has been resolved PaPBP1B is directly stimulated by LpoP but not by PaCpoB in vitro LpoP likely interacts between the GTase and UB2H domains of PaPBP1B
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Affiliation(s)
- Nathanael A Caveney
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver V6T 1Z3 BC, Canada
| | - Alexander J F Egan
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Isabel Ayala
- University of Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France
| | - Cédric Laguri
- University of Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France
| | - Craig S Robb
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver V6T 1Z3 BC, Canada
| | - Eefjan Breukink
- Department of Membrane Biochemistry and Biophysics, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology and Centre for Blood Research, The University of British Columbia, Vancouver V6T 1Z3 BC, Canada.
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