1
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Bartlett TM, Sisley TA, Mychack A, Walker S, Baker RW, Rudner DZ, Bernhardt TG. FacZ is a GpsB-interacting protein that prevents aberrant division-site placement in Staphylococcus aureus. Nat Microbiol 2024; 9:801-813. [PMID: 38443581 PMCID: PMC10914604 DOI: 10.1038/s41564-024-01607-y] [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: 04/24/2023] [Accepted: 01/15/2024] [Indexed: 03/07/2024]
Abstract
Staphylococcus aureus is a Gram-positive pathogen responsible for antibiotic-resistant infections. To identify vulnerabilities in cell envelope biogenesis that may overcome resistance, we enriched for S. aureus transposon mutants with defects in cell surface integrity or cell division by sorting for cells that stain with propidium iodide or have increased light-scattering properties, respectively. Transposon sequencing of the sorted populations identified more than 20 previously uncharacterized factors impacting these processes. Cells inactivated for one of these proteins, factor preventing extra Z-rings (FacZ, SAOUHSC_01855), showed aberrant membrane invaginations and multiple FtsZ cytokinetic rings. These phenotypes were suppressed in mutants lacking the conserved cell-division protein GpsB, which forms an interaction hub bridging envelope biogenesis factors with the cytokinetic ring in S. aureus. FacZ was found to interact directly with GpsB in vitro and in vivo. We therefore propose that FacZ is an envelope biogenesis factor that antagonizes GpsB function to prevent aberrant division events in S. aureus.
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Affiliation(s)
- Thomas M Bartlett
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Tyler A Sisley
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Aaron Mychack
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Suzanne Walker
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Richard W Baker
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David Z Rudner
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
| | - Thomas G Bernhardt
- Department of Microbiology Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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2
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Razew A, Laguri C, Vallet A, Bougault C, Kaus-Drobek M, Sabala I, Simorre JP. Staphylococcus aureus sacculus mediates activities of M23 hydrolases. Nat Commun 2023; 14:6706. [PMID: 37872144 PMCID: PMC10593780 DOI: 10.1038/s41467-023-42506-w] [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: 04/13/2023] [Accepted: 10/12/2023] [Indexed: 10/25/2023] Open
Abstract
Peptidoglycan, a gigadalton polymer, functions as the scaffold for bacterial cell walls and provides cell integrity. Peptidoglycan is remodelled by a large and diverse group of peptidoglycan hydrolases, which control bacterial cell growth and division. Over the years, many studies have focused on these enzymes, but knowledge on their action within peptidoglycan mesh from a molecular basis is scarce. Here, we provide structural insights into the interaction between short peptidoglycan fragments and the entire sacculus with two evolutionarily related peptidases of the M23 family, lysostaphin and LytM. Through nuclear magnetic resonance, mass spectrometry, information-driven modelling, site-directed mutagenesis and biochemical approaches, we propose a model in which peptidoglycan cross-linking affects the activity, selectivity and specificity of these two structurally related enzymes differently.
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Affiliation(s)
- Alicja Razew
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
- International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Cedric Laguri
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Alicia Vallet
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Catherine Bougault
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France
| | - Magdalena Kaus-Drobek
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland
| | - Izabela Sabala
- International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Street, 02-109, Warsaw, Poland.
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106, Warsaw, Poland.
| | - Jean-Pierre Simorre
- Universite Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 avenue des Martyrs-CS10090, Grenoble cedex 9, 38044, France.
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3
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Cerullo AR, McDermott MB, Pepi LE, Liu ZL, Barry D, Zhang S, Yang X, Chen X, Azadi P, Holford M, Braunschweig AB. Comparative mucomic analysis of three functionally distinct Cornu aspersum Secretions. Nat Commun 2023; 14:5361. [PMID: 37660066 PMCID: PMC10475054 DOI: 10.1038/s41467-023-41094-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 08/21/2023] [Indexed: 09/04/2023] Open
Abstract
Every animal secretes mucus, placing them among the most diverse biological materials. Mucus hydrogels are complex mixtures of water, ions, carbohydrates, and proteins. Uncertainty surrounding their composition and how interactions between components contribute to mucus function complicates efforts to exploit their properties. There is substantial interest in commercializing mucus from the garden snail, Cornu aspersum, for skincare, drug delivery, tissue engineering, and composite materials. C. aspersum secretes three mucus-one shielding the animal from environmental threats, one adhesive mucus from the pedal surface of the foot, and another pedal mucus that is lubricating. It remains a mystery how compositional differences account for their substantially different properties. Here, we characterize mucus proteins, glycosylation, ion content, and mechanical properties that could be used to provide insight into structure-function relationships through an integrative "mucomics" approach. We identify macromolecular components of these hydrogels, including a previously unreported protein class termed Conserved Anterior Mollusk Proteins (CAMPs). Revealing differences between C. aspersum mucus shows how considering structure at all levels can inform the design of mucus-inspired materials.
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Affiliation(s)
- Antonio R Cerullo
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA
- The PhD Program in Biochemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
- Department of Chemistry and Biochemistry, Hunter College, 695 Park Avenue, New York, NY, 10065, USA
| | - Maxwell B McDermott
- Department of Chemistry and Biochemistry, Hunter College, 695 Park Avenue, New York, NY, 10065, USA
| | - Lauren E Pepi
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Zhi-Lun Liu
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA
- Department of Chemical Engineering, The City College of New York, New York, NY, 10031, USA
| | - Diariou Barry
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Sheng Zhang
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA
| | - Xu Yang
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Xi Chen
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA
- Department of Chemical Engineering, The City College of New York, New York, NY, 10031, USA
- The PhD Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
- The PhD Program in Physics, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Mande Holford
- The PhD Program in Biochemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
- Department of Chemistry and Biochemistry, Hunter College, 695 Park Avenue, New York, NY, 10065, USA
- The PhD Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
- The PhD Program in Biology, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA
- Department of Invertebrate Zoology, The American Museum of Natural History, New York, NY, 10024, USA
| | - Adam B Braunschweig
- The Advanced Science Research Center, Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, NY, 10031, USA.
- The PhD Program in Biochemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA.
- Department of Chemistry and Biochemistry, Hunter College, 695 Park Avenue, New York, NY, 10065, USA.
- The PhD Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY, 10016, USA.
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4
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Sutton JAF, Cooke M, Tinajero-Trejo M, Wacnik K, Salamaga B, Portman-Ross C, Lund VA, Hobbs JK, Foster SJ. The roles of GpsB and DivIVA in Staphylococcus aureus growth and division. Front Microbiol 2023; 14:1241249. [PMID: 37711690 PMCID: PMC10498921 DOI: 10.3389/fmicb.2023.1241249] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/04/2023] [Indexed: 09/16/2023] Open
Abstract
The spheroid bacterium Staphylococcus aureus is often used as a model of morphogenesis due to its apparently simple cell cycle. S. aureus has many cell division proteins that are conserved across bacteria alluding to common functions. However, despite intensive study, we still do not know the roles of many of these components. Here, we have examined the functions of the paralogues DivIVA and GpsB in the S. aureus cell cycle. Cells lacking gpsB display a more spherical phenotype than the wild-type cells, which is associated with a decrease in peripheral cell wall peptidoglycan synthesis. This correlates with increased localization of penicillin-binding proteins at the developing septum, notably PBPs 2 and 3. Our results highlight the role of GpsB as an apparent regulator of cell morphogenesis in S. aureus.
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Affiliation(s)
- Joshua A. F. Sutton
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Mark Cooke
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
| | - Mariana Tinajero-Trejo
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Katarzyna Wacnik
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Bartłomiej Salamaga
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Callum Portman-Ross
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Victoria A. Lund
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Jamie K. Hobbs
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
- Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom
| | - Simon J. Foster
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
- The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
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5
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Bartlett TM, Sisley TA, Mychack A, Walker S, Baker RW, Rudner DZ, Bernhardt TG. Identification of FacZ as a division site placement factor in Staphylococcus aureus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538170. [PMID: 37162900 PMCID: PMC10168275 DOI: 10.1101/2023.04.24.538170] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Staphylococcus aureus is a gram-positive pathogen responsible for life-threatening infections that are difficult to treat due to antibiotic resistance. The identification of new vulnerabilities in essential processes like cell envelope biogenesis represents a promising avenue towards the development of anti-staphylococcal therapies that overcome resistance. To this end, we performed cell sorting-based enrichments for S. aureus mutants with defects in envelope integrity and cell division. We identified many known envelope biogenesis factors as well as a large collection of new factors with roles in this process. Mutants inactivated for one of the hits, the uncharacterized SAOUHSC_01855 protein, displayed aberrant membrane invaginations and multiple FtsZ cytokinetic ring structures. This factor is broadly distributed among Firmicutes, and its inactivation in B. subtilis similarly caused division and membrane defects. We therefore renamed the protein FacZ (Firmicute-associated coordinator of Z-rings). In S. aureus, inactivation of the conserved cell division protein GpsB suppressed the division and morphological defects of facZ mutants. Additionally, FacZ and GpsB were found to interact directly in a purified system. Thus, FacZ is a novel antagonist of GpsB function with a conserved role in controlling division site placement in S. aureus and other Firmicutes.
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Affiliation(s)
- Thomas M. Bartlett
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Tyler A. Sisley
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Aaron Mychack
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Suzanne Walker
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Richard W. Baker
- Department of Biochemistry & Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David Z. Rudner
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas G. Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, USA
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6
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Weaver A, Taguchi A, Dörr T. Masters of Misdirection: Peptidoglycan Glycosidases in Bacterial Growth. J Bacteriol 2023; 205:e0042822. [PMID: 36757204 PMCID: PMC10029718 DOI: 10.1128/jb.00428-22] [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] [Indexed: 02/10/2023] Open
Abstract
The dynamic composition of the peptidoglycan cell wall has been the subject of intense research for decades, yet how bacteria coordinate the synthesis of new peptidoglycan with the turnover and remodeling of existing peptidoglycan remains elusive. Diversity and redundancy within peptidoglycan synthases and peptidoglycan autolysins, enzymes that degrade peptidoglycan, have often made it challenging to assign physiological roles to individual enzymes and determine how those activities are regulated. For these reasons, peptidoglycan glycosidases, which cleave within the glycan strands of peptidoglycan, have proven veritable masters of misdirection over the years. Unlike many of the broadly conserved peptidoglycan synthetic complexes, diverse bacteria can employ unrelated glycosidases to achieve the same physiological outcome. Additionally, although the mechanisms of action for many individual enzymes have been characterized, apparent conserved homologs in other organisms can exhibit an entirely different biochemistry. This flexibility has been recently demonstrated in the context of three functions critical to vegetative growth: (i) release of newly synthesized peptidoglycan strands from their membrane anchors, (ii) processing of peptidoglycan turned over during cell wall expansion, and (iii) removal of peptidoglycan fragments that interfere with daughter cell separation during cell division. Finally, the regulation of glycosidase activity during these cell processes may be a cumulation of many factors, including protein-protein interactions, intrinsic substrate preferences, substrate availability, and subcellular localization. Understanding the true scope of peptidoglycan glycosidase activity will require the exploration of enzymes from diverse organisms with equally diverse growth and division strategies.
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Affiliation(s)
- Anna Weaver
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Atsushi Taguchi
- SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Ibaraki, Osaka, Japan
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
- Department of Microbiology, Cornell University, Ithaca, New York, USA
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, USA
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7
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Gu L, Xiao X, Zhao G, Kempen P, Zhao S, Liu J, Lee SY, Solem C. Rewiring the respiratory pathway of Lactococcus lactis to enhance extracellular electron transfer. Microb Biotechnol 2023; 16:1277-1292. [PMID: 36860178 DOI: 10.1111/1751-7915.14229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/22/2023] [Indexed: 03/03/2023] Open
Abstract
Lactococcus lactis, a lactic acid bacterium with a typical fermentative metabolism, can also use oxygen as an extracellular electron acceptor. Here we demonstrate, for the first time, that L. lactis blocked in NAD+ regeneration can use the alternative electron acceptor ferricyanide to support growth. By electrochemical analysis and characterization of strains carrying mutations in the respiratory chain, we pinpoint the essential role of the NADH dehydrogenase and 2-amino-3-carboxy-1,4-naphtoquinone in extracellular electron transfer (EET) and uncover the underlying pathway systematically. Ferricyanide respiration has unexpected effects on L. lactis, e.g., we find that morphology is altered from the normal coccoid to a more rod shaped appearance, and that acid resistance is increased. Using adaptive laboratory evolution (ALE), we successfully enhance the capacity for EET. Whole-genome sequencing reveals the underlying reason for the observed enhanced EET capacity to be a late-stage blocking of menaquinone biosynthesis. The perspectives of the study are numerous, especially within food fermentation and microbiome engineering, where EET can help relieve oxidative stress, promote growth of oxygen sensitive microorganisms and play critical roles in shaping microbial communities.
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Affiliation(s)
- Liuyan Gu
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Xinxin Xiao
- Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Ge Zhao
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Paul Kempen
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark.,National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Shuangqing Zhao
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jianming Liu
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Christian Solem
- National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
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8
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A Staphylococcal Glucosaminidase Drives Inflammatory Responses by Processing Peptidoglycan Chains to Physiological Lengths. Infect Immun 2023; 91:e0050022. [PMID: 36715551 PMCID: PMC9933629 DOI: 10.1128/iai.00500-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The peptidoglycan of Staphylococcus aureus is a critical cell envelope constituent and virulence factor that subverts host immune defenses and provides protection against environmental stressors. Peptidoglycan chains of the S. aureus cell wall are processed to characteristically short lengths by the glucosaminidase SagB. It is well established that peptidoglycan is an important pathogen-associated molecular pattern (PAMP) that is recognized by the host innate immune system and promotes production of proinflammatory cytokines, including interleukin-1β (IL-1β). However, how bacterial processing of peptidoglycan drives IL-1β production is comparatively unexplored. Here, we tested the involvement of staphylococcal glucosaminidases in shaping innate immune responses and identified SagB as a mediator of IL-1β production. A ΔsagB mutant fails to promote IL-1β production by macrophages and dendritic cells, and processing of peptidoglycan by SagB is essential for this response. SagB-dependent IL-1β production by macrophages is independent of canonical pattern recognition receptor engagement and NLRP3 inflammasome-mediated caspase activity. Instead, treatment of macrophages with heat-killed cells from a ΔsagB mutant leads to reduced caspase-independent cleavage of pro-IL-1β, resulting in accumulation of the pro form in the macrophage cytosol. Furthermore, SagB is required for virulence in systemic infection and promotes IL-1β production in a skin and soft tissue infection model. Taken together, our results suggest that the length of S. aureus cell wall glycan chains can drive IL-1β production by innate immune cells through a previously undescribed mechanism related to IL-1β maturation.
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9
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Comparative Genomics Identifies Novel Genetic Changes Associated with Oxacillin, Vancomycin and Daptomycin Susceptibility in ST100 Methicillin-Resistant Staphylococcus aureus. Antibiotics (Basel) 2023; 12:antibiotics12020372. [PMID: 36830286 PMCID: PMC9952151 DOI: 10.3390/antibiotics12020372] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
Infections due to vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA) represent a serious concern due to their association with vancomycin treatment failure. However, the underlying molecular mechanism responsible for the hVISA/VISA phenotype is complex and not yet fully understood. We have previously characterized two ST100-MRSA-hVISA clinical isolates recovered before and after 40 days of vancomycin treatment (D1 and D2, respectively) and two in vitro VISA derivatives (D23C9 and D2P11), selected independently from D2 in the presence of vancomycin. This follow-up study was aimed at further characterizing these isogenic strains and obtaining their whole genome sequences to unravel changes associated with antibiotic resistance. It is interesting to note that none of these isogenic strains carry SNPs in the regulatory operons vraUTSR, walKR and/or graXRS. Nonetheless, genetic changes including SNPs, INDELs and IS256 genomic insertions/rearrangements were found both in in vivo and in vitro vancomycin-selected strains. Some were found in the downstream target genes of the aforementioned regulatory operons, which are involved in cell wall and phosphate metabolism, staphylococcal growth and biofilm formation. Some of the genetic changes reported herein have not been previously associated with vancomycin, daptomycin and/or oxacillin resistance in S. aureus.
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10
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Kwan JMC, Qiao Y. Mechanistic Insights into the Activities of Major Families of Enzymes in Bacterial Peptidoglycan Assembly and Breakdown. Chembiochem 2023; 24:e202200693. [PMID: 36715567 DOI: 10.1002/cbic.202200693] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/28/2023] [Accepted: 01/30/2023] [Indexed: 01/31/2023]
Abstract
Serving as an exoskeletal scaffold, peptidoglycan is a polymeric macromolecule that is essential and conserved across all bacteria, yet is absent in mammalian cells; this has made bacterial peptidoglycan a well-established excellent antibiotic target. In addition, soluble peptidoglycan fragments derived from bacteria are increasingly recognised as key signalling molecules in mediating diverse intra- and inter-species communication in nature, including in gut microbiota-host crosstalk. Each bacterial species encodes multiple redundant enzymes for key enzymatic activities involved in peptidoglycan assembly and breakdown. In this review, we discuss recent findings on the biochemical activities of major peptidoglycan enzymes, including peptidoglycan glycosyltransferases (PGT) and transpeptidases (TPs) in the final stage of peptidoglycan assembly, as well as peptidoglycan glycosidases, lytic transglycosylase (LTs), amidases, endopeptidases (EPs) and carboxypeptidases (CPs) in peptidoglycan turnover and metabolism. Biochemical characterisation of these enzymes provides valuable insights into their substrate specificity, regulation mechanisms and potential modes of inhibition.
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Affiliation(s)
- Jeric Mun Chung Kwan
- School of Chemistry, Chemical Engineering and Biotechnology (CCEB), 21 Nanyang Link, Singapore, 637371, Singapore.,LKC School of Medicine, Nanyang Technological University (NTU) Singapore, 11 Mandalay Road, Singapore, Singapore, 208232, Singapore
| | - Yuan Qiao
- School of Chemistry, Chemical Engineering and Biotechnology (CCEB), Nanyang Technological University (NTU), Singapore, 21 Nanyang Link, Singapore, 637371, Singapore
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11
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Choo PY, Wang CY, VanNieuwenhze MS, Kline KA. Spatial and temporal localization of cell wall associated pili in Enterococcus faecalis. Mol Microbiol 2023; 119:1-18. [PMID: 36420961 PMCID: PMC10107303 DOI: 10.1111/mmi.15008] [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: 05/16/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Enterococcus faecalis virulence requires cell wall-associated proteins, including the sortase-assembled endocarditis and biofilm associated pilus (Ebp), important for biofilm formation in vitro and in vivo. The current paradigm for sortase-assembled pilus biogenesis in Gram-positive bacteria is that sortases attach substrates to lipid II peptidoglycan (PG) precursors, prior to their incorporation into the growing cell wall. Contrary to prevailing dogma, by following the distribution of Ebp and PG throughout the E. faecalis cell cycle, we found that cell surface Ebp do not co-localize with newly synthesized PG. Instead, surface-exposed Ebp are localized to the older cell hemisphere and excluded from sites of new PG synthesis at the septum. Moreover, Ebp deposition on the younger hemisphere of the E. faecalis diplococcus appear as foci adjacent to the nascent septum. We propose a new model whereby sortase substrate deposition can occur on older PG rather than at sites of new cell wall synthesis. Consistent with this model, we demonstrate that sequestering lipid II to block PG synthesis via ramoplanin, does not impact new Ebp deposition at the cell surface. These data support an alternative paradigm for sortase substrate deposition in E. faecalis, in which Ebp are anchored directly onto uncrosslinked cell wall, independent of new PG synthesis.
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Affiliation(s)
- Pei Yi Choo
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Charles Y Wang
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | | | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
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12
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Lund V, Gangotra H, Zhao Z, Sutton JAF, Wacnik K, DeMeester K, Liang H, Santiago C, Leimkuhler Grimes C, Jones S, Foster SJ. Coupling Novel Probes with Molecular Localization Microscopy Reveals Cell Wall Homeostatic Mechanisms in Staphylococcus aureus. ACS Chem Biol 2022; 17:3298-3305. [PMID: 36414253 PMCID: PMC9764285 DOI: 10.1021/acschembio.2c00741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Bacterial cell wall peptidoglycan is essential for viability, and its synthesis is targeted by antibiotics, including penicillin. To determine how peptidoglycan homeostasis controls cell architecture, growth, and division, we have developed novel labeling approaches. These are compatible with super-resolution fluorescence microscopy to examine peptidoglycan synthesis, hydrolysis, and the localization of the enzymes required for its biosynthesis (penicillin binding proteins (PBPs)). Synthesis of a cephalosporin-based fluorescent probe revealed a pattern of PBPs at the septum during division, supporting a model of dispersed peptidoglycan synthesis. Metabolic and hydroxylamine-based probes respectively enabled the synthesis of glycan strands and associated reducing termini of the peptidoglycan to be mapped. Foci and arcs of reducing termini appear as a result of both synthesis of glycan strands and glucosaminidase activity of the major peptidoglycan hydrolase, SagB. Our studies provide molecular level details of how essential peptidoglycan dynamics are controlled during growth and division.
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Affiliation(s)
- Victoria
A. Lund
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Haneesh Gangotra
- The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom
| | - Zhen Zhao
- The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom
| | - Joshua A. F. Sutton
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Katarzyna Wacnik
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Kristen DeMeester
- Department
of Chemistry and Biochemistry and Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, United States
| | - Hai Liang
- Department
of Chemistry and Biochemistry and Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, United States
| | - Cintia Santiago
- Department
of Chemistry and Biochemistry and Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, United States
| | - Catherine Leimkuhler Grimes
- Department
of Chemistry and Biochemistry and Department of Biological Sciences, University of Delaware, Newark, Delaware 19716, United States
| | - Simon Jones
- The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, United Kingdom,E-mail:
| | - Simon J. Foster
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, United Kingdom,The
Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, United Kingdom,E-mail:
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13
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Barbuti MD, Myrbråten IS, Morales Angeles D, Kjos M. The cell cycle of Staphylococcus aureus: An updated review. Microbiologyopen 2022; 12:e1338. [PMID: 36825883 PMCID: PMC9733580 DOI: 10.1002/mbo3.1338] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
As bacteria proliferate, DNA replication, chromosome segregation, cell wall synthesis, and cytokinesis occur concomitantly and need to be tightly regulated and coordinated. Although these cell cycle processes have been studied for decades, several mechanisms remain elusive, specifically in coccus-shaped cells such as Staphylococcus aureus. In recent years, major progress has been made in our understanding of how staphylococci divide, including new, fundamental insights into the mechanisms of cell wall synthesis and division site selection. Furthermore, several novel proteins and mechanisms involved in the regulation of replication initiation or progression of the cell cycle have been identified and partially characterized. In this review, we will summarize our current understanding of the cell cycle processes in the spheroid model bacterium S. aureus, with a focus on recent advances in the understanding of how these processes are regulated.
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Affiliation(s)
- Maria D. Barbuti
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Ine S. Myrbråten
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Danae Morales Angeles
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life Sciences (NMBU)ÅsNorway
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14
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Razew A, Schwarz JN, Mitkowski P, Sabala I, Kaus-Drobek M. One fold, many functions-M23 family of peptidoglycan hydrolases. Front Microbiol 2022; 13:1036964. [PMID: 36386627 PMCID: PMC9662197 DOI: 10.3389/fmicb.2022.1036964] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 10/05/2022] [Indexed: 12/02/2023] Open
Abstract
Bacterial cell walls are the guards of cell integrity. They are composed of peptidoglycan that provides rigidity to sustain internal turgor and ensures isolation from the external environment. In addition, they harbor the enzymatic machinery to secure cell wall modulations needed throughout the bacterial lifespan. The main players in this process are peptidoglycan hydrolases, a large group of enzymes with diverse specificities and different mechanisms of action. They are commonly, but not exclusively, found in prokaryotes. Although in most cases, these enzymes share the same molecular function, namely peptidoglycan hydrolysis, they are leveraged to perform a variety of physiological roles. A well-investigated family of peptidoglycan hydrolases is M23 peptidases, which display a very conserved fold, but their spectrum of lytic action is broad and includes both Gram- positive and Gram- negative bacteria. In this review, we summarize the structural, biochemical, and functional studies concerning the M23 family of peptidases based on literature and complement this knowledge by performing large-scale analyses of available protein sequences. This review has led us to gain new insight into the role of surface charge in the activity of this group of enzymes. We present relevant conclusions drawn from the analysis of available structures and indicate the main structural features that play a crucial role in specificity determination and mechanisms of latency. Our work systematizes the knowledge of the M23 family enzymes in the context of their unique antimicrobial potential against drug-resistant pathogens and presents possibilities to modulate and engineer their features to develop perfect antibacterial weapons.
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Affiliation(s)
| | | | | | - Izabela Sabala
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Magdalena Kaus-Drobek
- Laboratory of Protein Engineering, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
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15
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Meng Y, Wang Q, Ma Z, Li W, Niu K, Zhu T, Lin H, Lu C, Fan H. Streptococcal autolysin promotes dysfunction of swine tracheal epithelium by interacting with vimentin. PLoS Pathog 2022; 18:e1010765. [PMID: 35921364 PMCID: PMC9377611 DOI: 10.1371/journal.ppat.1010765] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 08/15/2022] [Accepted: 07/25/2022] [Indexed: 11/24/2022] Open
Abstract
Streptococcus suis serotype 2 (SS2) is a major zoonotic pathogen resulting in manifestations as pneumonia and septic shock. The upper respiratory tract is typically thought to be the main colonization and entry site of SS2 in pigs, but the mechanism through which it penetrates the respiratory barrier is still unclear. In this study, a mutant with low invasive potential to swine tracheal epithelial cells (STECs) was screened from the TnYLB-1 transposon insertion mutant library of SS2, and the interrupted gene was identified as autolysin (atl). Compared to wild-type (WT) SS2, Δatl mutant exhibited lower ability to penetrate the tracheal epithelial barrier in a mouse model. Purified Atl also enhanced SS2 translocation across STEC monolayers in Transwell inserts. Furthermore, Atl redistributed the tight junctions (TJs) in STECs through myosin light chain kinase (MLCK) signaling, which led to increased barrier permeability. Using mass spectrometry, co-immunoprecipitation (co-IP), pull-down, bacterial two-hybrid and saturation binding experiments, we showed that Atl binds directly to vimentin. CRISPR/Cas9-targeted deletion of vimentin in STECs (VIM KO STECs) abrogated the capacity of SS2 to translocate across the monolayers, SS2-induced phosphorylation of myosin II regulatory light chain (MLC) and MLCK transcription, indicating that vimentin is indispensable for MLCK activation. Consistently, vimentin null mice were protected from SS2 infection and exhibited reduced tracheal and lung injury. Thus, MLCK-mediated epithelial barrier opening caused by the Atl-vimentin interaction is found to be likely the key mechanism by which SS2 penetrates the tracheal epithelium. Streptococcus suis serotype 2 (SS2), an emerging zoonotic agent, can breach the respiratory barrier and cause invasive disease in pigs. Here, we identified the novel role of autolysin Atl in penetration of the respiratory barrier by SS2 and its systemic dissemination and identified its binding partner, vimentin, a type III intermediate filament protein. Atl contributed to the MLCK-triggered redistribution of tight junctions to open the tracheal epithelial barrier. Knockout of vimentin abolished the ability of SS2 to penetrate the monolayer barrier and the activation of MLCK. Furthermore, vimentin null mice were protected from infection by intranasally administered SS2. This study is the first to demonstrate that the interaction between the GBS Bsp-like domain of Atl and vimentin promotes MLCK-mediated dysfunction of the epithelial barrier, which may provide theoretical information for prophylactic and/or therapeutic treatments against diseases caused by similar respiratory pathogens.
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Affiliation(s)
- Yu Meng
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Qing Wang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Zhe Ma
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Weiyi Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Kai Niu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Ting Zhu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Huixing Lin
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Chengping Lu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
| | - Hongjie Fan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
- * E-mail:
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16
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Wang M, Buist G, van Dijl JM. Staphylococcus aureus cell wall maintenance - the multifaceted roles of peptidoglycan hydrolases in bacterial growth, fitness, and virulence. FEMS Microbiol Rev 2022; 46:6604383. [PMID: 35675307 PMCID: PMC9616470 DOI: 10.1093/femsre/fuac025] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/22/2022] [Accepted: 05/25/2022] [Indexed: 01/07/2023] Open
Abstract
Staphylococcus aureus is an important human and livestock pathogen that is well-protected against environmental insults by a thick cell wall. Accordingly, the wall is a major target of present-day antimicrobial therapy. Unfortunately, S. aureus has mastered the art of antimicrobial resistance, as underscored by the global spread of methicillin-resistant S. aureus (MRSA). The major cell wall component is peptidoglycan. Importantly, the peptidoglycan network is not only vital for cell wall function, but it also represents a bacterial Achilles' heel. In particular, this network is continuously opened by no less than 18 different peptidoglycan hydrolases (PGHs) encoded by the S. aureus core genome, which facilitate bacterial growth and division. This focuses attention on the specific functions executed by these enzymes, their subcellular localization, their control at the transcriptional and post-transcriptional levels, their contributions to staphylococcal virulence and their overall importance in bacterial homeostasis. As highlighted in the present review, our understanding of the different aspects of PGH function in S. aureus has been substantially increased over recent years. This is important because it opens up new possibilities to exploit PGHs as innovative targets for next-generation antimicrobials, passive or active immunization strategies, or even to engineer them into effective antimicrobial agents.
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Affiliation(s)
- Min Wang
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, the Netherlands
| | | | - Jan Maarten van Dijl
- Corresponding author: Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. box 30001, HPC EB80, 9700 RB Groningen, the Netherlands, Tel. +31-50-3615187; Fax. +31-50-3619105; E-mail:
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17
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Weidenbacher PAB, Rodriguez-Rivera FP, Sanyal M, Visser JA, Do J, Bertozzi CR, Kim PS. Chemically Modified Bacterial Sacculi as a Vaccine Microparticle Scaffold. ACS Chem Biol 2022; 17:1184-1196. [PMID: 35412807 PMCID: PMC9127789 DOI: 10.1021/acschembio.2c00140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
![]()
Vaccine scaffolds
and carrier proteins increase the immunogenicity
of subunit vaccines. Here, we developed, characterized, and demonstrated
the efficacy of a novel microparticle vaccine scaffold comprised of
bacterial peptidoglycan (PGN), isolated as an entire sacculi. The
PGN microparticles contain bio-orthogonal chemical handles allowing
for site-specific attachment of immunogens. We first evaluated the
purification, integrity, and immunogenicity of PGN microparticles
derived from a variety of bacterial species. We then optimized PGN
microparticle modification conditions; Staphylococcus
aureus PGN microparticles containing azido-d-alanine yielded robust conjugation to immunogens. We then demonstrated
that this vaccine scaffold elicits comparable immunostimulation to
the conventional carrier protein, keyhole limpet hemocyanin (KLH).
We further modified the S. aureus PGN
microparticle to contain the SARS-CoV-2 receptor-binding domain (RBD)—this
conjugate vaccine elicited neutralizing antibody titers comparable
to those elicited by the KLH-conjugated RBD. Collectively, these findings
suggest that chemically modified bacterial PGN microparticles are
a conjugatable and biodegradable microparticle scaffold capable of
eliciting a robust immune response toward an antigen of interest.
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Affiliation(s)
- Payton A.-B. Weidenbacher
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Frances P. Rodriguez-Rivera
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mrinmoy Sanyal
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Biochemistry, School of Medicine, Stanford University, Stanford, California 94305, United States
| | - Joshua A. Visser
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jonathan Do
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Biochemistry, School of Medicine, Stanford University, Stanford, California 94305, United States
| | - Carolyn R. Bertozzi
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Peter S. Kim
- Stanford ChEM-H, Stanford University, Stanford, California 94305, United States
- Department of Biochemistry, School of Medicine, Stanford University, Stanford, California 94305, United States
- Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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18
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Haubrich BA, Nayyab S, Gallati M, Hernandez J, Williams C, Whitman A, Zimmerman T, Li Q, Chen Y, Zhou CZ, Basu A, Reid CW. Inhibition of Streptococcus pneumoniae growth by masarimycin. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35467499 DOI: 10.1099/mic.0.001182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Despite renewed interest, development of chemical biology methods to study peptidoglycan metabolism has lagged in comparison to the glycobiology field in general. To address this, a panel of diamides were screened against the Gram-positive bacterium Streptococcus pneumoniae to identify inhibitors of bacterial growth. The screen identified the diamide masarimycin as a bacteriostatic inhibitor of S. pneumoniae growth with an MIC of 8 µM. The diamide inhibited detergent-induced autolysis in a concentration-dependent manner, indicating perturbation of peptidoglycan degradation as the mode-of-action. Cell based screening of masarimycin against a panel of autolysin mutants, identified a higher MIC against a ΔlytB strain lacking an endo-N-acetylglucosaminidase involved in cell division. Subsequent biochemical and phenotypic analyses suggested that the higher MIC was due to an indirect interaction with LytB. Further analysis of changes to the cell surface in masarimycin treated cells identified the overexpression of several moonlighting proteins, including elongation factor Tu which is implicated in regulating cell shape. Checkerboard assays using masarimycin in concert with additional antibiotics identified an antagonistic relationship with the cell wall targeting antibiotic fosfomycin, which further supports a cell wall mode-of-action.
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Affiliation(s)
- Brad A Haubrich
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA.,Department of Basic Sciences, Touro University Nevada, College of Osteopathic Medicine, Henderson, NV 89014, USA
| | - Saman Nayyab
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA.,Amherst Department of Molecular and Cellular Biology, University of Massachusetts, 230 Stockbridge Rd Amherst, MA, USA
| | - Mika Gallati
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA
| | - Jazmeen Hernandez
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA
| | - Caroline Williams
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA
| | - Andrew Whitman
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA
| | - Tahl Zimmerman
- Department of Family and Consumer Sciences, North Carolina A&T State University, Greensboro, NC, USA
| | - Qiong Li
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, PR China
| | - Yuxing Chen
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, PR China
| | - Cong-Zhao Zhou
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, PR China
| | - Amit Basu
- Department of Chemistry, Brown University, Providence, RI, USA
| | - Christopher W Reid
- Center for Health and Behavioral Sciences, Department of Science and Technology, Bryant University, 1150 Douglas Pike, Smithfield, RI 02917, USA
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19
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The Major Autolysin Atl Regulates the Virulence of Staphylococcus aureus by Controlling the Sorting of LukAB. Infect Immun 2022; 90:e0005622. [PMID: 35258336 PMCID: PMC9022505 DOI: 10.1128/iai.00056-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Infections caused by the Gram-positive bacterium Staphylococcus aureus remain a significant health threat globally. The production of bicomponent pore-forming leukocidins plays an important role in S. aureus pathogenesis. Transcriptionally, these toxins are primarily regulated by the Sae and Agr regulatory systems. However, the posttranslational regulation of these toxins is largely unexplored. In particular, one of the leukocidins, LukAB, has been shown to be both secreted into the extracellular milieu and associated with the bacterial cell envelope. Here, we report that a major cell wall hydrolase, autolysin (Atl), controls the sorting of LukAB from the cell envelope to the extracellular milieu, an effect independent of transcriptional regulation. By influencing the sorting of LukAB, Atl modulates S. aureus cytotoxicity toward primary human neutrophils. Mechanistically, we found that the reduction in peptidoglycan cleavage and increased LukAB secretion in the atl mutant can be reversed through the supplementation of exogenous mutanolysin. Altogether, our study revealed that the cell wall hydrolase activity of Atl and the cleavage of peptidoglycan play an important role in controlling the sorting of S. aureus toxins during secretion.
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20
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Demonstration of the role of cell wall homeostasis in Staphylococcus aureus growth and the action of bactericidal antibiotics. Proc Natl Acad Sci U S A 2021; 118:2106022118. [PMID: 34716264 PMCID: PMC8612353 DOI: 10.1073/pnas.2106022118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 09/02/2021] [Indexed: 12/29/2022] Open
Abstract
Bacterial cell wall peptidoglycan is essential, maintaining both cellular integrity and morphology, in the face of internal turgor pressure. Peptidoglycan synthesis is important, as it is targeted by cell wall antibiotics, including methicillin and vancomycin. Here, we have used the major human pathogen Staphylococcus aureus to elucidate both the cell wall dynamic processes essential for growth (life) and the bactericidal effects of cell wall antibiotics (death) based on the principle of coordinated peptidoglycan synthesis and hydrolysis. The death of S. aureus due to depletion of the essential, two-component and positive regulatory system for peptidoglycan hydrolase activity (WalKR) is prevented by addition of otherwise bactericidal cell wall antibiotics, resulting in stasis. In contrast, cell wall antibiotics kill via the activity of peptidoglycan hydrolases in the absence of concomitant synthesis. Both methicillin and vancomycin treatment lead to the appearance of perforating holes throughout the cell wall due to peptidoglycan hydrolases. Methicillin alone also results in plasmolysis and misshapen septa with the involvement of the major peptidoglycan hydrolase Atl, a process that is inhibited by vancomycin. The bactericidal effect of vancomycin involves the peptidoglycan hydrolase SagB. In the presence of cell wall antibiotics, the inhibition of peptidoglycan hydrolase activity using the inhibitor complestatin results in reduced killing, while, conversely, the deregulation of hydrolase activity via loss of wall teichoic acids increases the death rate. For S. aureus, the independent regulation of cell wall synthesis and hydrolysis can lead to cell growth, death, or stasis, with implications for the development of new control regimes for this important pathogen.
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21
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The cell envelope of Staphylococcus aureus selectively controls the sorting of virulence factors. Nat Commun 2021; 12:6193. [PMID: 34702812 PMCID: PMC8548510 DOI: 10.1038/s41467-021-26517-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/05/2021] [Indexed: 11/08/2022] Open
Abstract
Staphylococcus aureus bi-component pore-forming leukocidins are secreted toxins that directly target and lyse immune cells. Intriguingly, one of the leukocidins, Leukocidin AB (LukAB), is found associated with the bacterial cell envelope in addition to secreted into the extracellular milieu. Here, we report that retention of LukAB on the bacterial cells provides S. aureus with a pre-synthesized active toxin that kills immune cells. On the bacteria, LukAB is distributed as discrete foci in two distinct compartments: membrane-proximal and surface-exposed. Through genetic screens, we show that a membrane lipid, lysyl-phosphatidylglycerol (LPG), and lipoteichoic acid (LTA) contribute to LukAB deposition and release. Furthermore, by studying non-covalently surface-bound proteins we discovered that the sorting of additional exoproteins, such as IsaB, Hel, ScaH, and Geh, are also controlled by LPG and LTA. Collectively, our study reveals a multistep secretion system that controls exoprotein storage and protein translocation across the S. aureus cell wall.
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22
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Masters EA, Muthukrishnan G, Ho L, Gill AL, de Mesy Bentley KL, Galloway CA, McGrath JL, Awad HA, Gill SR, Schwarz EM. Staphylococcus aureus Cell Wall Biosynthesis Modulates Bone Invasion and Osteomyelitis Pathogenesis. Front Microbiol 2021; 12:723498. [PMID: 34484165 PMCID: PMC8415456 DOI: 10.3389/fmicb.2021.723498] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/15/2021] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus invasion of the osteocyte lacuno-canalicular network (OLCN) is a novel mechanism of bacterial persistence and immune evasion in chronic osteomyelitis. Previous work highlighted S. aureus cell wall transpeptidase, penicillin binding protein 4 (PBP4), and surface adhesin, S. aureus surface protein C (SasC), as critical factors for bacterial deformation and propagation through nanopores in vitro, representative of the confined canaliculi in vivo. Given these findings, we hypothesized that cell wall synthesis machinery and surface adhesins enable durotaxis- and haptotaxis-guided invasion of the OLCN, respectively. Here, we investigated select S. aureus cell wall synthesis mutants (Δpbp3, Δatl, and ΔmreC) and surface adhesin mutants (ΔclfA and ΔsasC) for nanopore propagation in vitro and osteomyelitis pathogenesis in vivo. In vitro evaluation in the microfluidic silicon membrane-canalicular array (μSiM-CA) showed pbp3, atl, clfA, and sasC deletion reduced nanopore propagation. Using a murine model for implant-associated osteomyelitis, S. aureus cell wall synthesis proteins were found to be key modulators of S. aureus osteomyelitis pathogenesis, while surface adhesins had minimal effects. Specifically, deletion of pbp3 and atl decreased septic implant loosening and S. aureus abscess formation in the medullary cavity, while deletion of surface adhesins showed no significant differences. Further, peri-implant osteolysis, osteoclast activity, and receptor activator of nuclear factor kappa-B ligand (RANKL) production were decreased following pbp3 deletion. Most notably, transmission electron microscopy (TEM) imaging of infected bone showed that pbp3 was the only gene herein associated with decreased submicron invasion of canaliculi in vivo. Together, these results demonstrate that S. aureus cell wall synthesis enzymes are critical for OLCN invasion and osteomyelitis pathogenesis in vivo.
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Affiliation(s)
- Elysia A Masters
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States
| | - Gowrishankar Muthukrishnan
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Orthopaedics, University of Rochester Medical Center, Rochester, NY, United States
| | - Lananh Ho
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States
| | - Ann Lindley Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States
| | - Karen L de Mesy Bentley
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Orthopaedics, University of Rochester Medical Center, Rochester, NY, United States.,Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, United States
| | - Chad A Galloway
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, United States
| | - James L McGrath
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States
| | - Hani A Awad
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States
| | - Steven R Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States
| | - Edward M Schwarz
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States.,Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States.,Department of Orthopaedics, University of Rochester Medical Center, Rochester, NY, United States.,Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, United States
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23
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Regulated cleavage of glycan strands by the murein hydrolase SagB in S. aureus involves a direct interaction with LyrA (SpdC). J Bacteriol 2021; 203:JB.00014-21. [PMID: 33593946 PMCID: PMC8092163 DOI: 10.1128/jb.00014-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
LyrA (SpdC), a homologue of eukaryotic CAAX proteases that act on prenylated substrates, has been implicated in the assembly of several pathways of the envelope of Staphylococcus aureus. We described earlier the Lysostaphin resistance (Lyr) and Staphylococcal protein A display (Spd) phenotypes associated with loss of the lyrA (spdC) gene. However, a direct contribution to the assembly of pentaglycine crossbridges, the target of lysostaphin cleavage in S. aureus peptidoglycan, or of Staphylococcal protein A attachment to peptidoglycan could not be attributed directly to LyrA (SpdC). These two processes are catalyzed by the Fem factors and Sortase A, respectively. To gain insight into the function of LyrA (SpdC), here we use affinity chromatography and LC-MS/MS analysis and report that LyrA interacts with SagB. SagB cleaves glycan strands of peptidoglycan to achieve physiological length. Similar to sagB peptidoglycan, lyrA peptidoglycan contains extended glycan strands. Purified lyrA peptidoglycan can still be cleaved to physiological length by SagB in vitro LyrA does not modify or cleave peptidoglycan, it also does not modify or stabilize SagB. The membrane bound domain of LyrA is sufficient to support SagB activity but predicted 'CAAX enzyme' catalytic residues in this domain are dispensable. We speculate that LyrA exerts its effect on bacterial prenyl substrates, specifically undecaprenol-bound peptidoglycan substrates of SagB, to help control glycan length. Such an activity also explains the Lyr and Spd phenotypes observed earlier.IMPORTANCE Peptidoglycan is assembled on the trans side of the plasma membrane from lipid II precursors into glycan chains that are crosslinked at stem peptides. In S. aureus, SagB, a membrane-associated N-acetylglucosaminidase, cleaves polymerized glycan chains to their physiological length. Deletion of sagB is associated with longer glycan strands in peptidoglycan, altered protein trafficking and secretion in the envelope, and aberrant excretion of cytosolic proteins. It is not clear whether SagB, with its single transmembrane segment, serves as the molecular ruler of glycan chains or whether other factors modulate its activity. Here, we show that LyrA (SpdC), a protein of the CAAX type II prenyl endopeptidase family, modulates SagB activity via interaction though its transmembrane domain.
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24
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Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction. PLoS Pathog 2021; 17:e1009468. [PMID: 33788901 PMCID: PMC8041196 DOI: 10.1371/journal.ppat.1009468] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/12/2021] [Accepted: 03/12/2021] [Indexed: 01/09/2023] Open
Abstract
Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease. The prevalence of methicillin resistant Staphylococcus aureus (MRSA) in both hospitals and the wider community places a huge weight on healthcare providers. To discover new control regimes, it is therefore important to understand how the pathogen behaves within the relevant environment of the host. This is often hampered by the ability to obtain sufficient ex vivo pathogen samples for study. We have developed a method to isolate S. aureus from the infected host to be able to analyse cellular morphology and structure. S. aureus, isolated from an infected kidney abscess are smaller in size, with thicker cell walls than exponentially growing cells in vitro. Their cell wall peptidoglycan also is less crosslinked. These features suggested the role of components controlling cell wall homeostasis as being important for infections. We tested the role of PBP4, known to increase cell wall crosslinking and found a pbp4 mutant to have increased survival in macrophages and fitness within the murine host. Conversely the peptidoglycan hydrolase SagB, whose loss results in thinner cell walls was attenuated in the murine systemic model of infection, with concomitant loss of fitness within macrophages. Our study reveals an important adaptation to the host environment and the role of those components involved in cell wall homeostasis in vivo.
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25
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Fisher JF, Mobashery S. β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium. Chem Rev 2021; 121:3412-3463. [PMID: 33373523 PMCID: PMC8653850 DOI: 10.1021/acs.chemrev.0c01010] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
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26
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Müller M, Calvert M, Hottmann I, Kluj RM, Teufel T, Balbuchta K, Engelbrecht A, Selim KA, Xu Q, Borisova M, Titz A, Mayer C. The exo-β-N-acetylmuramidase NamZ from Bacillus subtilis is the founding member of a family of exo-lytic peptidoglycan hexosaminidases. J Biol Chem 2021; 296:100519. [PMID: 33684445 PMCID: PMC8054146 DOI: 10.1016/j.jbc.2021.100519] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/27/2021] [Accepted: 03/04/2021] [Indexed: 11/11/2022] Open
Abstract
Endo-β-N-acetylmuramidases, commonly known as lysozymes, are well-characterized antimicrobial enzymes that catalyze an endo-lytic cleavage of peptidoglycan; i.e., they hydrolyze the β-1,4-glycosidic bonds connecting N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc). In contrast, little is known about exo-β-N-acetylmuramidases, which catalyze an exo-lytic cleavage of β-1,4-MurNAc entities from the non-reducing ends of peptidoglycan chains. Such an enzyme was identified earlier in the bacterium Bacillus subtilis, but the corresponding gene has remained unknown so far. We now report that ybbC of B. subtilis, renamed namZ, encodes the reported exo-β-N-acetylmuramidase. A ΔnamZ mutant accumulated specific cell wall fragments and showed growth defects under starvation conditions, indicating a role of NamZ in cell wall turnover and recycling. Recombinant NamZ protein specifically hydrolyzed the artificial substrate para-nitrophenyl β-MurNAc and the peptidoglycan-derived disaccharide MurNAc-β-1,4-GlcNAc. Together with the exo-β-N-acetylglucosaminidase NagZ and the exo-muramoyl-l-alanine amidase AmiE, NamZ degraded intact peptidoglycan by sequential hydrolysis from the non-reducing ends. A structure model of NamZ, built on the basis of two crystal structures of putative orthologs from Bacteroides fragilis, revealed a two-domain structure including a Rossmann-fold-like domain that constitutes a unique glycosidase fold. Thus, NamZ, a member of the DUF1343 protein family of unknown function, is now classified as the founding member of a new family of glycosidases (CAZy GH171; www.cazy.org/GH171.html). NamZ-like peptidoglycan hexosaminidases are mainly present in the phylum Bacteroidetes and less frequently found in individual genomes within Firmicutes (Bacilli, Clostridia), Actinobacteria, and γ-proteobacteria.
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Affiliation(s)
- Maraike Müller
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Matthew Calvert
- Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarbrücken, Germany; Deutsches Zentrum für Infektionsforschung (DZIF), Standort Hannover-Braunschweig, Germany; Department of Chemistry, Saarland University, Saarbrücken, Germany
| | - Isabel Hottmann
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Robert Maria Kluj
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Tim Teufel
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Katja Balbuchta
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Alicia Engelbrecht
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Khaled A Selim
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany; Chemistry of Natural and Microbial Products Department, Pharmaceutical and Drug Industries Research Division, National Research Center, Giza, Egypt
| | - Qingping Xu
- GM/CA @ APS, Argonne National Laboratory, Lemont, Illinois, USA
| | - Marina Borisova
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Alexander Titz
- Chemical Biology of Carbohydrates, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarbrücken, Germany; Deutsches Zentrum für Infektionsforschung (DZIF), Standort Hannover-Braunschweig, Germany; Department of Chemistry, Saarland University, Saarbrücken, Germany
| | - Christoph Mayer
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany.
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27
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Molecular dynamics model for the antibactericity of textured surfaces. Colloids Surf B Biointerfaces 2021; 199:111504. [PMID: 33418209 DOI: 10.1016/j.colsurfb.2020.111504] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 11/30/2020] [Indexed: 11/20/2022]
Abstract
An original model has been developed for the initial stage of bacterial adhesion on textured surfaces. Based on molecular dynamics, the model describes contact between individual bacterial cells in a planktonic state and a surface, accounting for both the mechanical properties of the cells and the physico-chemical mechanisms governing interaction with the substrate. Feasibility of the model is assessed via comparison with experimental results of bacterial growth on stainless steel substrates textured with ultrashort laser pulses. Simulations are performed for two different bacterial species, Staphylococcus aureus and Escherichia coli, on two distinct surface types characterised by elongated ripples and isolated nanopillars, respectively. Calculated results are in agreement with experiment outcomes and highlight the role of mechanical stresses within the cell wall due to deformation upon interaction with the substrate, creating unfavourable conditions for bacteria during the initial phases of adhesion. Furthermore, the flexibility of the model provides insight into the intricate interplay between topography and the physico-chemical properties of the substrate, pointing to a unified picture of the mechanisms underlying bacterial affinity to a textured surface.
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28
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Garde S, Chodisetti PK, Reddy M. Peptidoglycan: Structure, Synthesis, and Regulation. EcoSal Plus 2021; 9:eESP-0010-2020. [PMID: 33470191 PMCID: PMC11168573 DOI: 10.1128/ecosalplus.esp-0010-2020] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Peptidoglycan is a defining feature of the bacterial cell wall. Initially identified as a target of the revolutionary beta-lactam antibiotics, peptidoglycan has become a subject of much interest for its biology, its potential for the discovery of novel antibiotic targets, and its role in infection. Peptidoglycan is a large polymer that forms a mesh-like scaffold around the bacterial cytoplasmic membrane. Peptidoglycan synthesis is vital at several stages of the bacterial cell cycle: for expansion of the scaffold during cell elongation and for formation of a septum during cell division. It is a complex multifactorial process that includes formation of monomeric precursors in the cytoplasm, their transport to the periplasm, and polymerization to form a functional peptidoglycan sacculus. These processes require spatio-temporal regulation for successful assembly of a robust sacculus to protect the cell from turgor and determine cell shape. A century of research has uncovered the fundamentals of peptidoglycan biology, and recent studies employing advanced technologies have shed new light on the molecular interactions that govern peptidoglycan synthesis. Here, we describe the peptidoglycan structure, synthesis, and regulation in rod-shaped bacteria, particularly Escherichia coli, with a few examples from Salmonella and other diverse organisms. We focus on the pathway of peptidoglycan sacculus elongation, with special emphasis on discoveries of the past decade that have shaped our understanding of peptidoglycan biology.
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Affiliation(s)
- Shambhavi Garde
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Pavan Kumar Chodisetti
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Manjula Reddy
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
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29
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New insights in the coordinated amidase and glucosaminidase activity of the major autolysin (Atl) in Staphylococcus aureus. Commun Biol 2020; 3:695. [PMID: 33219282 PMCID: PMC7679415 DOI: 10.1038/s42003-020-01405-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 10/15/2020] [Indexed: 11/17/2022] Open
Abstract
After bacterial cell division, the daughter cells are still covalently interlinked by the peptidoglycan network which is resolved by specific hydrolases (autolysins) to release the daughter cells. In staphylococci, the major autolysin (Atl) with its two domain enzymes, N-acetylmuramyl-L-alanine amidase (AmiA) and β-N-acetylglucosaminidase (GlcA), resolves the peptidoglycan to release the daughter cells. Internal deletions in each of the enzyme domains revealed defined morphological alterations such as cell cluster formation in ΔamiA, ΔglcA and Δatl, and asymmetric cell division in the ΔglcA. A most important finding was that GlcA activity requires the prior removal of the stem peptide by AmiA for its activity thus the naked glycan strand is its substrate. Furthermore, GlcA is not an endo-β-N-acetylglucosaminidase but an exo-enzyme that cuts the glycan backbone to disaccharides independent of its O-acetylation modification. Our results shed new light into the sequential peptidoglycan hydrolysis by AmiA and GlcA during cell division in staphylococci. Nega et al. shed light on the interplay of the two domain enzymes of the major autolysin, AmiA and GlcA, in S. aureus for peptidoglycan hydrolysis during bacterial cell division. They show that GlcA requires the prior removal of the stem peptide by AmiA for its activity and that GlcA is not an endo-enzyme as previously thought, but an exo-enzyme that chops down the glycan backbone to disaccharides independent of its O-acetylation modification.
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30
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Structure and reconstitution of a hydrolase complex that may release peptidoglycan from the membrane after polymerization. Nat Microbiol 2020; 6:34-43. [PMID: 33168989 PMCID: PMC7755832 DOI: 10.1038/s41564-020-00808-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 10/02/2020] [Indexed: 12/24/2022]
Abstract
Bacteria are surrounded by a peptidoglycan cell wall that is essential for their survival1. During cell wall assembly, a lipid-linked disaccharide-peptide precursor called Lipid II is polymerized and crosslinked to produce mature peptidoglycan. As Lipid II is polymerized, nascent polymers remain membrane-anchored at one end and the other end becomes crosslinked to the matrix2–4. A longstanding question is how bacteria release newly synthesized peptidoglycan strands from the membrane to complete the synthesis of mature peptidoglycan. Here we show that a Staphylococcus aureus cell wall hydrolase and a membrane protein containing eight transmembrane helices form a complex that may function as a peptidoglycan release factor. The complex cleaves nascent peptidoglycan internally to produce free oligomers as well as lipid-linked oligomers that can undergo further elongation. The polytopic membrane protein, which is similar to a eukaryotic CAAX protease, controls the length of these products. A 2.6 Å resolution structure of the complex shows that the membrane protein scaffolds the hydrolase to orient its active site for cleavage of the glycan strand. We propose that this complex serves to detach newly-synthesized peptidoglycan polymer from the cell membrane to complete integration into the cell wall matrix.
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31
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Masters EA, de Mesy Bentley KL, Gill AL, Hao SP, Galloway CA, Salminen AT, Guy DR, McGrath JL, Awad HA, Gill SR, Schwarz EM. Identification of Penicillin Binding Protein 4 (PBP4) as a critical factor for Staphylococcus aureus bone invasion during osteomyelitis in mice. PLoS Pathog 2020; 16:e1008988. [PMID: 33091079 PMCID: PMC7608983 DOI: 10.1371/journal.ppat.1008988] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/03/2020] [Accepted: 09/17/2020] [Indexed: 12/03/2022] Open
Abstract
Staphylococcus aureus infection of bone is challenging to treat because it colonizes the osteocyte lacuno-canalicular network (OLCN) of cortical bone. To elucidate factors involved in OLCN invasion and identify novel drug targets, we completed a hypothesis-driven screen of 24 S. aureus transposon insertion mutant strains for their ability to propagate through 0.5 μm-sized pores in the Microfluidic Silicon Membrane Canalicular Arrays (μSiM-CA), developed to model S. aureus invasion of the OLCN. This screen identified the uncanonical S. aureus transpeptidase, penicillin binding protein 4 (PBP4), as a necessary gene for S. aureus deformation and propagation through nanopores. In vivo studies revealed that Δpbp4 infected tibiae treated with vancomycin showed a significant 12-fold reduction in bacterial load compared to WT infected tibiae treated with vancomycin (p<0.05). Additionally, Δpbp4 infected tibiae displayed a remarkable decrease in pathogenic bone-loss at the implant site with and without vancomycin therapy. Most importantly, Δpbp4 S. aureus failed to invade and colonize the OLCN despite high bacterial loads on the implant and in adjacent tissues. Together, these results demonstrate that PBP4 is required for S. aureus colonization of the OLCN and suggest that inhibitors may be synergistic with standard of care antibiotics ineffective against bacteria within the OLCN. Staphylococcus aureus is the most prevalent pathogen in osteomyelitis, and its infection of bone is difficult to cure. S. aureus colonization of the osteocyte lacuno-canalicular network (OLCN) of cortical bone has been identified as a novel pathogenetic mechanism in chronic osteomyelitis. To elucidate factors involved in OLCN invasion, we conducted an in vitro genetic screen that identified pbp4 as a critical gene for S. aureus cell deformation and propagation through nanopores and demonstrated that PBP4 is critical for OLCN colonization in murine osteomyelitis. Thus, PBP4 inhibitors may be novel drugs to treat osteomyelitis in combination with standard of care antibiotics.
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Affiliation(s)
- Elysia A. Masters
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Karen L. de Mesy Bentley
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Orthopaedics, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Ann Lindley Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Stephanie P. Hao
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Chad A. Galloway
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Alec T. Salminen
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Diamond R. Guy
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
| | - James L. McGrath
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Hani A. Awad
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Steven R. Gill
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Edward M. Schwarz
- Center for Musculoskeletal Research, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Biomedical Engineering, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Orthopaedics, University of Rochester Medical Center, Rochester, NY, United States of America
- * E-mail:
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32
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Harper CE, Hernandez CJ. Cell biomechanics and mechanobiology in bacteria: Challenges and opportunities. APL Bioeng 2020; 4:021501. [PMID: 32266323 PMCID: PMC7113033 DOI: 10.1063/1.5135585] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/27/2020] [Indexed: 12/11/2022] Open
Abstract
Physical forces play a profound role in the survival and function of all known forms of life. Advances in cell biomechanics and mechanobiology have provided key insights into the physiology of eukaryotic organisms, but much less is known about the roles of physical forces in bacterial physiology. This review is an introduction to bacterial mechanics intended for persons familiar with cells and biomechanics in mammalian cells. Bacteria play a major role in human health, either as pathogens or as beneficial commensal organisms within the microbiome. Although bacteria have long been known to be sensitive to their mechanical environment, understanding the effects of physical forces on bacterial physiology has been limited by their small size (∼1 μm). However, advancements in micro- and nano-scale technologies over the past few years have increasingly made it possible to rigorously examine the mechanical stress and strain within individual bacteria. Here, we review the methods currently used to examine bacteria from a mechanical perspective, including the subcellular structures in bacteria and how they differ from those in mammalian cells, as well as micro- and nanomechanical approaches to studying bacteria, and studies showing the effects of physical forces on bacterial physiology. Recent findings indicate a large range in mechanical properties of bacteria and show that physical forces can have a profound effect on bacterial survival, growth, biofilm formation, and resistance to toxins and antibiotics. Advances in the field of bacterial biomechanics have the potential to lead to novel antibacterial strategies, biotechnology approaches, and applications in synthetic biology.
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Affiliation(s)
- Christine E. Harper
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA
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Pasquina-Lemonche L, Burns J, Turner RD, Kumar S, Tank R, Mullin N, Wilson JS, Chakrabarti B, Bullough PA, Foster SJ, Hobbs JK. The architecture of the Gram-positive bacterial cell wall. Nature 2020; 582:294-297. [PMID: 32523118 PMCID: PMC7308169 DOI: 10.1038/s41586-020-2236-6] [Citation(s) in RCA: 189] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/25/2020] [Indexed: 02/05/2023]
Abstract
The primary structural component of the bacterial cell wall is peptidoglycan, which is essential for viability and the synthesis of which is the target for crucial antibiotics1,2. Peptidoglycan is a single macromolecule made of glycan chains crosslinked by peptide side branches that surrounds the cell, acting as a constraint to internal turgor1,3. In Gram-positive bacteria, peptidoglycan is tens of nanometres thick, generally portrayed as a homogeneous structure that provides mechanical strength4-6. Here we applied atomic force microscopy7-12 to interrogate the morphologically distinct Staphylococcus aureus and Bacillus subtilis species, using live cells and purified peptidoglycan. The mature surface of live cells is characterized by a landscape of large (up to 60 nm in diameter), deep (up to 23 nm) pores constituting a disordered gel of peptidoglycan. The inner peptidoglycan surface, consisting of more nascent material, is much denser, with glycan strand spacing typically less than 7 nm. The inner surface architecture is location dependent; the cylinder of B. subtilis has dense circumferential orientation, while in S. aureus and division septa for both species, peptidoglycan is dense but randomly oriented. Revealing the molecular architecture of the cell envelope frames our understanding of its mechanical properties and role as the environmental interface13,14, providing information complementary to traditional structural biology approaches.
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Affiliation(s)
- L Pasquina-Lemonche
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
- The Florey Institute, University of Sheffield, Sheffield, UK
| | - J Burns
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - R D Turner
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
- Department of Computer Science, University of Sheffield, Sheffield, UK
| | - S Kumar
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - R Tank
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - N Mullin
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - J S Wilson
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - B Chakrabarti
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - P A Bullough
- Krebs Institute, University of Sheffield, Sheffield, UK
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - S J Foster
- Krebs Institute, University of Sheffield, Sheffield, UK.
- The Florey Institute, University of Sheffield, Sheffield, UK.
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK.
| | - J K Hobbs
- Krebs Institute, University of Sheffield, Sheffield, UK.
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK.
- The Florey Institute, University of Sheffield, Sheffield, UK.
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Domain sliding of two Staphylococcus aureus N-acetylglucosaminidases enables their substrate-binding prior to its catalysis. Commun Biol 2020; 3:178. [PMID: 32313083 PMCID: PMC7170848 DOI: 10.1038/s42003-020-0911-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/23/2020] [Indexed: 12/22/2022] Open
Abstract
To achieve productive binding, enzymes and substrates must align their geometries to complement each other along an entire substrate binding site, which may require enzyme flexibility. In pursuit of novel drug targets for the human pathogen S. aureus, we studied peptidoglycan N-acetylglucosaminidases, whose structures are composed of two domains forming a V-shaped active site cleft. Combined insights from crystal structures supported by site-directed mutagenesis, modeling, and molecular dynamics enabled us to elucidate the substrate binding mechanism of SagB and AtlA-gl. This mechanism requires domain sliding from the open form observed in their crystal structures, leading to polysaccharide substrate binding in the closed form, which can enzymatically process the bound substrate. We suggest that these two hydrolases must exhibit unusual extents of flexibility to cleave the rigid structure of a bacterial cell wall.
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Do T, Page JE, Walker S. Uncovering the activities, biological roles, and regulation of bacterial cell wall hydrolases and tailoring enzymes. J Biol Chem 2020; 295:3347-3361. [PMID: 31974163 DOI: 10.1074/jbc.rev119.010155] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacteria account for 1000-fold more biomass than humans. They vary widely in shape and size. The morphological diversity of bacteria is due largely to the different peptidoglycan-based cell wall structures that encase bacterial cells. Although the basic structure of peptidoglycan is highly conserved, consisting of long glycan strands that are cross-linked by short peptide chains, the mature cell wall is chemically diverse. Peptidoglycan hydrolases and cell wall-tailoring enzymes that regulate glycan strand length, the degree of cross-linking, and the addition of other modifications to peptidoglycan are central in determining the final architecture of the bacterial cell wall. Historically, it has been difficult to biochemically characterize these enzymes that act on peptidoglycan because suitable peptidoglycan substrates were inaccessible. In this review, we discuss fundamental aspects of bacterial cell wall synthesis, describe the regulation and diverse biochemical and functional activities of peptidoglycan hydrolases, and highlight recently developed methods to make and label defined peptidoglycan substrates. We also review how access to these substrates has now enabled biochemical studies that deepen our understanding of how bacterial cell wall enzymes cooperate to build a mature cell wall. Such improved understanding is critical to the development of new antibiotics that disrupt cell wall biogenesis, a process essential to the survival of bacteria.
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Affiliation(s)
- Truc Do
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Julia E Page
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115
| | - Suzanne Walker
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts 02115.
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Odermatt PD, Hannebelle MTM, Eskandarian HA, Nievergelt AP, McKinney JD, Fantner GE. Overlapping and essential roles for molecular and mechanical mechanisms in mycobacterial cell division. NATURE PHYSICS 2020; 16:57-62. [PMID: 31921326 PMCID: PMC6952280 DOI: 10.1038/s41567-019-0679-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/04/2019] [Indexed: 05/30/2023]
Abstract
Mechanisms to control cell division are essential for cell proliferation and survival 1. Bacterial cell growth and division require the coordinated activity of peptidoglycan synthases and hydrolytic enzymes 2-4 to maintain mechanical integrity of the cell wall 5. Recent studies suggest that cell separation is governed by mechanical forces 6,7. How mechanical forces interact with molecular mechanisms to control bacterial cell division in space and time is poorly understood. Here, we use a combination of atomic force microscope (AFM) imaging, nanomechanical mapping, and nanomanipulation to show that enzymatic activity and mechanical forces serve overlapping and essential roles in mycobacterial cell division. We find that mechanical stress gradually accumulates in the cell wall concentrated at the future division site, culminating in rapid (millisecond) cleavage of nascent sibling cells. Inhibiting cell wall hydrolysis delays cleavage; conversely, locally increasing cell wall stress causes instantaneous and premature cleavage. Cells deficient in peptidoglycan hydrolytic activity fail to locally decrease their cell wall strength and undergo natural cleavage, instead forming chains of non-growing cells. Cleavage of these cells can be mechanically induced by local application of stress with AFM. These findings establish a direct link between actively controlled molecular mechanisms and passively controlled mechanical forces in bacterial cell division.
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Affiliation(s)
- Pascal D. Odermatt
- Laboratory for Bio- and Nano-Instrumentation, School of Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
| | - Mélanie T. M. Hannebelle
- Laboratory for Bio- and Nano-Instrumentation, School of Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
| | - Haig A. Eskandarian
- Laboratory for Bio- and Nano-Instrumentation, School of Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
| | - Adrian P. Nievergelt
- Laboratory for Bio- and Nano-Instrumentation, School of Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
| | - John D. McKinney
- Laboratory of Microbiology and Microtechnology, School of Life Sciences, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
| | - Georg E. Fantner
- Laboratory for Bio- and Nano-Instrumentation, School of Engineering, Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland
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Rani G, Patri I. Importance of being cross-linked for the bacterial cell wall. Phys Rev E 2019; 100:062408. [PMID: 31962385 DOI: 10.1103/physreve.100.062408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Indexed: 06/10/2023]
Abstract
The bacterial cell wall is primarily composed of a mesh of glycan strands cross-linked by peptide bridges and is essential for safeguarding the cell. The structure of the cell wall has to be stiff enough to bear the high turgor pressure and sufficiently tough to ensure protection against failure. Here we explore the role of various design features of the cell in enhancing the toughness of the cell wall. We explain how the glycan strand length distribution, the degree of cross-linking and the placement of the cross-links on the glycan strands can act in tandem to ensure that the cell wall offers sufficient resistance to propagation of cracks. Further, we suggest a possible mechanism by which peptide bond hydrolysis, via judicious cleaving of peptide cross-links, can act to mitigate this risk of failure. We also study the reinforcing effect of MreB cytoskeleton, which can offer a degree of safety to the cell wall. However, we show that the cross-linked structure of the cell wall is its primary line of defense against mechanical failure.
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Affiliation(s)
- Garima Rani
- Institute of Mathematical Sciences, C I T Campus, Chennai 600 113, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Issan Patri
- Chennai Mathematical Institute, SIPCOT IT Park, Siruseri, Chennai 603103, India
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Coe KA, Lee W, Stone MC, Komazin-Meredith G, Meredith TC, Grad YH, Walker S. Multi-strain Tn-Seq reveals common daptomycin resistance determinants in Staphylococcus aureus. PLoS Pathog 2019; 15:e1007862. [PMID: 31738809 PMCID: PMC6934316 DOI: 10.1371/journal.ppat.1007862] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 12/27/2019] [Accepted: 09/24/2019] [Indexed: 01/30/2023] Open
Abstract
Antibiotic-resistant Staphylococcus aureus remains a leading cause of antibiotic resistance-associated mortality in the United States. Given the reality of multi-drug resistant infections, it is imperative that we establish and maintain a pipeline of new compounds to replace or supplement our current antibiotics. A first step towards this goal is to prioritize targets by identifying the genes most consistently required for survival across the S. aureus phylogeny. Here we report the first direct comparison of multiple strains of S. aureus via transposon sequencing. We show that mutant fitness varies by strain in key pathways, underscoring the importance of using more than one strain to differentiate between core and strain-dependent essential genes. We treated the libraries with daptomycin to assess whether the strain-dependent differences impact pathways important for survival. Despite baseline differences in gene importance, several pathways, including the lipoteichoic acid pathway, consistently promote survival under daptomycin exposure, suggesting core vulnerabilities that can be exploited to resensitize daptomycin-nonsusceptible isolates. We also demonstrate the merit of using transposons with outward-facing promoters capable of overexpressing nearby genes for identifying clinically-relevant gain-of-function resistance mechanisms. Together, the daptomycin vulnerabilities and resistance mechanisms support a mode of action with wide-ranging effects on the cell envelope and cell division. This work adds to a growing body of literature demonstrating the nuanced insights gained by comparing Tn-Seq results across multiple bacterial strains. Antibiotic-resistant Staphylococcus aureus kills thousands of people every year in the United States alone. To stay ahead of the looming threat of multidrug-resistant infections, we must continue to develop new antibiotics and find ways to make our current repertoire of antibiotics more effective, including by finding pairs of compounds that perform best when administered together. In the age of next-generation sequencing, we can now use transposon sequencing to find potential targets for new antibiotics on a genome-wide scale, identified as either essential genes or genes that positively influence survival in the presence of an antibiotic. In this work, we created a compendium of genes that are essential across a range of S. aureus strains, as well as those that are important for growth in the presence of the antibiotic daptomycin. The results will be a resource for researchers working to develop the next generation of antibiotic therapies.
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Affiliation(s)
- Kathryn A. Coe
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Wonsik Lee
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Madeleine C. Stone
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gloria Komazin-Meredith
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Pennsylvania, United States of America
| | - Timothy C. Meredith
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, Pennsylvania, United States of America
- * E-mail: (TCM); (YHG); (SW)
| | - Yonatan H. Grad
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
- Division of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (TCM); (YHG); (SW)
| | - Suzanne Walker
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States of America
- * E-mail: (TCM); (YHG); (SW)
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Bacterial Swarming Reduces Proteus mirabilis and Vibrio parahaemolyticus Cell Stiffness and Increases β-Lactam Susceptibility. mBio 2019; 10:mBio.00210-19. [PMID: 31594808 PMCID: PMC6786863 DOI: 10.1128/mbio.00210-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteus mirabilis and Vibrio parahaemolyticus are bacteria that infect humans. To adapt to environmental changes, these bacteria alter their cell morphology and move collectively to access new sources of nutrients in a process referred to as “swarming.” We found that changes in the composition and thickness of the peptidoglycan layer of the cell wall make swarmer cells of P. mirabilis and V. parahaemolyticus more flexible (i.e., reduce cell stiffness) and that they become more sensitive to osmotic pressure and cell wall-targeting antibiotics (e.g., β-lactams). These results highlight the importance of assessing the extracellular environment in determining antibiotic doses and the use of β-lactam antibiotics for treating infections caused by swarmer cells of P. mirabilis and V. parahaemolyticus. Swarmer cells of the Gram-negative uropathogenic bacteria Proteus mirabilis and Vibrio parahaemolyticus become long (>10 to 100 μm) and multinucleate during their growth and motility on polymer surfaces. We demonstrated that the increasing cell length is accompanied by a large increase in flexibility. Using a microfluidic assay to measure single-cell mechanics, we identified large differences in the swarmer cell stiffness (bending rigidity) of P. mirabilis (5.5 × 10−22 N m2) and V. parahaemolyticus (1.0 × 10−22 N m2) compared to vegetative cells (1.4 × 10−20 N m2 and 2.2 × 10−22 N m2, respectively). The reduction in bending rigidity (∼2-fold to ∼26-fold) was accompanied by a decrease in the average polysaccharide strand length of the peptidoglycan layer of the cell wall from 28 to 30 disaccharides to 19 to 22 disaccharides. Atomic force microscopy revealed a reduction in P. mirabilis peptidoglycan thickness from 1.5 nm (vegetative cells) to 1.0 nm (swarmer cells), and electron cryotomography indicated changes in swarmer cell wall morphology. P. mirabilis and V. parahaemolyticus swarmer cells became increasingly sensitive to osmotic pressure and susceptible to cell wall-modifying antibiotics (compared to vegetative cells)—they were ∼30% more likely to die after 3 h of treatment with MICs of the β-lactams cephalexin and penicillin G. The adaptive cost of “swarming” was offset by the increase in cell susceptibility to physical and chemical changes in their environment, thereby suggesting the development of new chemotherapies for bacteria that leverage swarming for the colonization of hosts and for survival.
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Mayer C, Kluj RM, Mühleck M, Walter A, Unsleber S, Hottmann I, Borisova M. Bacteria's different ways to recycle their own cell wall. Int J Med Microbiol 2019; 309:151326. [PMID: 31296364 DOI: 10.1016/j.ijmm.2019.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 05/28/2019] [Accepted: 06/30/2019] [Indexed: 01/05/2023] Open
Abstract
The ability to recover components of their own cell wall is a common feature of bacteria. This was initially recognized in the Gram-negative bacterium Escherichia coli, which recycles about half of the peptidoglycan of its cell wall during one cell doubling. Moreover, E. coli was shown to grow on peptidoglycan components provided as nutrients. A distinguished recycling enzyme of E. coli required for both, recovery of the cell wall sugar N-acetylmuramic acid (MurNAc) of the own cell wall and for growth on external MurNAc, is the MurNAc 6-phosphate (MurNAc 6P) lactyl ether hydrolase MurQ. We revealed however, that most Gram-negative bacteria lack a murQ ortholog and instead harbor a pathway, absent in E. coli, that channels MurNAc directly to peptidoglycan biosynthesis. This "anabolic recycling pathway" bypasses the initial steps of peptidoglycan de novo synthesis, including the target of the antibiotic fosfomycin, thus providing intrinsic resistance to the antibiotic. The Gram-negative oral pathogen Tannerella forsythia is auxotrophic for MurNAc and apparently depends on the anabolic recycling pathway to synthesize its own cell wall by scavenging cell wall debris of other bacteria. In contrast, Gram-positive bacteria lack the anabolic recycling genes, but mostly contain one or two murQ orthologs. Quantification of MurNAc 6P accumulation in murQ mutant cells by mass spectrometry allowed us to demonstrate for the first time that Gram-positive bacteria do recycle their own peptidoglycan. This had been questioned earlier, since peptidoglycan turnover products accumulate in the spent media of Gram-positives. We showed, that these fragments are recovered during nutrient limitation, which prolongs starvation survival of Bacillus subtilis and Staphylococcus aureus. Peptidoglycan recycling in these bacteria however differs, as the cell wall is either cleaved exhaustively and monosaccharide building blocks are taken up (B. subtilis) or disaccharides are released and recycled involving a novel phosphomuramidase (MupG; S.aureus). In B. subtilis also the teichoic acids, covalently bound to the peptidoglycan (wall teichoic acids; WTAs), are recycled. During phosphate limitation, the sn-glycerol-3-phosphate phosphodiesterase GlpQ specifically degrades WTAs of B. subtilis. In S. aureus, in contrast, GlpQ is used to scavenge external teichoic acid sources. Thus, although bacteria generally recover their own cell wall, they apparently apply distinct strategies for breakdown and reutilization of cell wall fragments. This review summarizes our work on this topic funded between 2011 and 2019 by the DFG within the collaborative research center SFB766.
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Affiliation(s)
- Christoph Mayer
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany.
| | - Robert Maria Kluj
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Maraike Mühleck
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Axel Walter
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Sandra Unsleber
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Isabel Hottmann
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Marina Borisova
- Mikrobiologie/Biotechnologie, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin Tübingen (IMIT), Eberhard Karls Universität Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
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Schneewind O, Missiakas DM. Staphylococcal Protein Secretion and Envelope Assembly. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0070-2019. [PMID: 31267890 PMCID: PMC7028390 DOI: 10.1128/microbiolspec.gpp3-0070-2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Indexed: 12/13/2022] Open
Abstract
The highly cross-linked peptidoglycan represents the rigid layer of the bacterial envelope and protects bacteria from osmotic lysis. In Gram-positive bacteria, peptidoglycan also functions as a scaffold for the immobilization of capsular polysaccharide, wall teichoic acid (WTA), and surface proteins. This chapter captures recent development on the assembly of the envelope of Staphylococcus aureus including mechanisms accounting for immobilization of molecules to peptidoglycan as well as hydrolysis of peptidoglycan for the specific release of bound molecules, facilitation of protein secretion across the envelope and cell division. Peptidoglycan, WTA and capsular polysaccharide are directly synthesized onto undecaprenol. Surface proteins are anchored by Sortase A, a membrane-embedded transpeptidase that scans secreted polypeptides for the C-terminal LPXTG motif of sorting signals. The resulting acyl enzyme intermediate is resolved by lipid II, the undecaprenol-bound peptidoglycan precursor. While these pathways share membrane diffusible undecaprenol, assembly of these molecules occurs either at the cross-walls or the cell poles. In S. aureus, the cross-wall represents the site of de novo peptidoglycan synthesis which is eventually split to complete the cell cycle yielding newly divided daughter cells. Peptidoglycan synthesized at the cross-wall is initially devoid of WTA. Conversely, lipoteichoic acid (LTA) synthesis which does not require bactoprenol is seemingly restricted to septal membranes. Similarly, S. aureus distinguishes two types of surface protein precursors. Polypeptides with canonical signal peptides are deposited at the cell poles, whereas precursors with conserved YSIRK-GXXS motif signal peptides traffic to the cross-wall. A model for protein trafficking in the envelope and uneven distribution of teichoic acids is discussed.
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Affiliation(s)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637
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Porfírio S, Carlson RW, Azadi P. Elucidating Peptidoglycan Structure: An Analytical Toolset. Trends Microbiol 2019; 27:607-622. [DOI: 10.1016/j.tim.2019.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/16/2019] [Accepted: 01/29/2019] [Indexed: 01/04/2023]
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Abstract
Dating back to the 1960s, initial studies on the staphylococcal cell wall were driven by the need to clarify the mode of action of the first antibiotics and the resistance mechanisms developed by the bacteria. During the following decades, the elucidation of the biosynthetic path and primary composition of staphylococcal cell walls was propelled by advances in microbial cell biology, specifically, the introduction of high-resolution analytical techniques and molecular genetic approaches. The field of staphylococcal cell wall gradually gained its own significance as the complexity of its chemical structure and involvement in numerous cellular processes became evident, namely its versatile role in host interactions, coordination of cell division and environmental stress signaling.This chapter includes an updated description of the anatomy of staphylococcal cell walls, paying particular attention to information from the last decade, under four headings: high-resolution analysis of the Staphylococcus aureus peptidoglycan; variations in peptidoglycan composition; genetic determinants and enzymes in cell wall synthesis; and complex functions of cell walls. The latest contributions to a more precise picture of the staphylococcal cell envelope were possible due to recently developed state-of-the-art microscopy and spectroscopy techniques and to a wide combination of -omics approaches, that are allowing to obtain a more integrative view of this highly dynamic structure.
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Affiliation(s)
- Rita Sobral
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
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Abstract
The peptidoglycan sacculus is a net-like polymer that surrounds the cytoplasmic membrane in most bacteria. It is essential to maintain the bacterial cell shape and protect from turgor. The peptidoglycan has a basic composition, common to all bacteria, with species-specific variations that can modify its biophysical properties or the pathogenicity of the bacteria. The synthesis of peptidoglycan starts in the cytoplasm and the precursor lipid II is flipped across the cytoplasmic membrane. The new peptidoglycan strands are synthesised and incorporated into the pre-existing sacculus by the coordinated activities of peptidoglycan synthases and hydrolases. In the model organism Escherichia coli there are two complexes required for the elongation and division. Each of them is regulated by different proteins from both the cytoplasmic and periplasmic sides that ensure the well-coordinated synthesis of new peptidoglycan.
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Kluj RM, Ebner P, Adamek M, Ziemert N, Mayer C, Borisova M. Recovery of the Peptidoglycan Turnover Product Released by the Autolysin Atl in Staphylococcus aureus Involves the Phosphotransferase System Transporter MurP and the Novel 6-phospho- N-acetylmuramidase MupG. Front Microbiol 2018; 9:2725. [PMID: 30524387 PMCID: PMC6262408 DOI: 10.3389/fmicb.2018.02725] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/24/2018] [Indexed: 11/29/2022] Open
Abstract
The peptidoglycan of the bacterial cell wall undergoes a permanent turnover during cell growth and differentiation. In the Gram-positive pathogen Staphylococcus aureus, the major peptidoglycan hydrolase Atl is required for accurate cell division, daughter cell separation and autolysis. Atl is a bifunctional N-acetylmuramoyl-L-alanine amidase/endo-β-N-acetylglucosaminidase that releases peptides and the disaccharide N-acetylmuramic acid-β-1,4-N-acetylglucosamine (MurNAc-GlcNAc) from the peptido-glycan. Here we revealed the recycling pathway of the cell wall turnover product MurNAc-GlcNAc in S. aureus. The latter disaccharide is internalized and concomitantly phosphorylated by the phosphotransferase system (PTS) transporter MurP, which had been implicated previously in the uptake and phosphorylation of MurNAc. Since MurP mutant cells accumulate MurNAc-GlcNAc and not MurNAc in the culture medium during growth, the disaccharide represents the physiological substrate of the PTS transporter. We further identified and characterized a novel 6-phospho-N-acetylmuramidase, named MupG, which intracellularly hydrolyses MurNAc 6-phosphate-GlcNAc, the product of MurP-uptake and phosphorylation, yielding MurNAc 6-phosphate and GlcNAc. MupG is the first characterized representative of a novel family of glycosidases containing domain of unknown function 871 (DUF871). The corresponding gene mupG (SAUSA300_0192) of S. aureus strain USA300 is the first gene within a putative operon that also includes genes encoding the MurNAc 6-phosphate etherase MurQ, MurP, and the putative transcriptional regulator MurR. Using mass spectrometry, we observed cytoplasmic accumulation of MurNAc 6-phosphate-GlcNAc in ΔmupG and ΔmupGmurQ markerless non-polar deletion mutants, but not in the wild type or in the complemented ΔmupG strain. MurNAc 6-phosphate-GlcNAc levels in the mutants increased during stationary phase, in accordance with previous observations regarding peptidoglycan recycling in S. aureus.
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Affiliation(s)
- Robert Maria Kluj
- Microbiology/Biotechnology, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Patrick Ebner
- Microbial Genetics, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Martina Adamek
- Microbiology/Biotechnology, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Nadine Ziemert
- Microbiology/Biotechnology, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Christoph Mayer
- Microbiology/Biotechnology, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| | - Marina Borisova
- Microbiology/Biotechnology, Department of Biology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
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Hanczarek I, Kenna AJ, Lindensmith C, Nadeau J. Performance of Fluorescent Cell-Labeling Dyes under Simulated Europa Mission Radiation Doses. Radiat Res 2018; 190:634. [PMID: 30325265 DOI: 10.1667/rr15187.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We investigated the performance of several commonly used fluorescent dyes after exposure to a simulated Europa mission total ionizing radiation dose of 300 krad (3 kGy) applied using a 60Co source. Dyes irradiated in aqueous solution or as lyophilized powders were evaluated for absorbance and emission spectra, quantum yield, and where appropriate, ability to label cells or nucleic acids. Although some dyes showed significant increase or decrease in quantum yield with the dose, their spectra and cell-labeling properties remained essentially unchanged after irradiation in powder form. Irradiation in aqueous solution led to significantly greater changes, including a large blue shift in the DNA intercalator propidium iodide. These results suggest that many fluorescent probes are appropriate for use in astrobiological missions to Europa, but that SYTO9 and propidium iodide should be used with caution or not mixed with each other, as is commonly done in "Live/Dead" labeling applications.
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Affiliation(s)
- Iulia Hanczarek
- a Department of Physics, Portland State University, Portland, Oregon 97201
| | - Aaron J Kenna
- b Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Chris Lindensmith
- b Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Jay Nadeau
- a Department of Physics, Portland State University, Portland, Oregon 97201
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EssH Peptidoglycan Hydrolase Enables Staphylococcus aureus Type VII Secretion across the Bacterial Cell Wall Envelope. J Bacteriol 2018; 200:JB.00268-18. [PMID: 30082459 DOI: 10.1128/jb.00268-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/31/2018] [Indexed: 11/20/2022] Open
Abstract
The ESAT-6-like secretion system (ESS) of Staphylococcus aureus is assembled in the bacterial membrane from core components that promote the secretion of WXG-like proteins (EsxA, EsxB, EsxC, and EsxD) and the EssD effector. Genes encoding the ESS secretion machinery components, effector, and WXG-like proteins are located in the ess locus. Here, we identify essH, a heretofore uncharacterized gene of the ess locus, whose product is secreted via an N-terminal signal peptide into the extracellular medium of staphylococcal cultures. EssH exhibits two peptidoglycan hydrolase activities, cleaving the pentaglycine cross bridge and the amide bond of N-acetylmuramyl-l-alanine, thereby separating glycan chains and wall peptides with cleaved cross bridges. Unlike other peptidoglycan hydrolases, EssH does not promote the lysis of staphylococci. EssH residues Cys199 and His254, which are conserved in other CHAP domain enzymes, are required for peptidoglycan hydrolase activity and for S. aureus ESS secretion. These data suggest that EssH and its murein hydrolase activity are required for protein secretion by the ESS pathway.IMPORTANCE Gene clusters encoding WXG-like proteins and FtsK/SpoIIIE-like P loop ATPases in Firmicutes encode type 7b secretion systems (T7bSS) for the transport of select protein substrates. The Staphylococcus aureus T7bSS assembles in the bacterial membrane and promotes the secretion of WXG-like proteins and effectors. The mechanisms whereby staphylococci extend the T7SS across the bacterial cell wall envelope are not known. Here, we show that staphylococci secrete EssH to cleave their peptidoglycan, thereby enabling T7bSS transport of proteins across the bacterial cell wall envelope.
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Borišek J, Pintar S, Ogrizek M, Grdadolnik SG, Hodnik V, Turk D, Perdih A, Novič M. Discovery of (phenylureido)piperidinyl benzamides as prospective inhibitors of bacterial autolysin E from Staphylococcus aureus. J Enzyme Inhib Med Chem 2018; 33:1239-1247. [PMID: 30141354 PMCID: PMC6116672 DOI: 10.1080/14756366.2018.1493474] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Autolysin E (AtlE) is a cell wall degrading enzyme that catalyzes the hydrolysis of the β-1,4-glycosidic bond between the N-acetylglucosamine and N-acetylmuramic acid units of the bacterial peptidoglycan. Using our recently determined crystal structure of AtlE from Staphylococcus aureus and a combination of pharmacophore modeling, similarity search, and molecular docking, a series of (Phenylureido)piperidinyl benzamides were identified as potential binders and surface plasmon resonance (SPR) and saturation-transfer difference (STD) NMR experiments revealed that discovered compounds bind to AtlE in a lower micromolar range. (phenylureido)piperidinyl benzamides are the first reported non-substrate-like compounds that interact with this enzyme and enable further study of the interaction of small molecules with bacterial AtlE as potential inhibitors of this target.
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Affiliation(s)
- Jure Borišek
- a National Institute of Chemistry , Ljubljana , Slovenia
| | - Sara Pintar
- b Department of Biochemistry, Molecular and Structural Biology , Jozef Stefan Institute , Ljubljana , Slovenia.,c Jozef Stefan International Postgraduate School , Ljubljana , Slovenia
| | - Mitja Ogrizek
- a National Institute of Chemistry , Ljubljana , Slovenia
| | | | - Vesna Hodnik
- d Biotechnical Faculty , Infrastructural Center for Surface Plasmon Resonance , Ljubljana , Slovenia
| | - Dušan Turk
- b Department of Biochemistry, Molecular and Structural Biology , Jozef Stefan Institute , Ljubljana , Slovenia.,e Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins , Ljubljana , Slovenia
| | - Andrej Perdih
- a National Institute of Chemistry , Ljubljana , Slovenia
| | - Marjana Novič
- a National Institute of Chemistry , Ljubljana , Slovenia
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den Blaauwen T. Is Longitudinal Division in Rod-Shaped Bacteria a Matter of Swapping Axis? Front Microbiol 2018; 9:822. [PMID: 29867786 PMCID: PMC5952006 DOI: 10.3389/fmicb.2018.00822] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 04/11/2018] [Indexed: 01/21/2023] Open
Abstract
The morphology of bacterial species shows a wealth of variation from star-shaped to spherical and rod- to spiral-shaped, to mention a few. Their mode of growth and division is also very diverse and flexible ranging from polar growth and lateral surface increase to midcell expansion and from perpendicular to longitudinal asymmetric division. Gammaproteobacterial rod-shaped species such as Escherchia coli divide perpendicularly and grow in length, whereas the genetically very similar rod-shaped symbiotic Thiosymbion divide longitudinally, and some species even divide asynchronously while growing in width. The ovococcal Streptococcus pneumoniae also lengthens and divides perpendicularly, yet it is genetically very different from E. coli. Are these differences as dramatic as is suggested by visual inspection, or can they all be achieved by subtle variation in the regulation of the same protein complexes that synthesize the cell envelope? Most bacteria rely on the cytoskeletal polymer FtsZ to organize cell division, but only a subset of species use the actin homolog MreB for length growth, although some of them are morphologically not that different. Poles are usually negative determinant for cell division. Curved cell poles can be inert or active with respect to peptidoglycan synthesis, can localize chemotaxis and other sensing proteins or other bacterial equipment, such as pili, depending on the species. But what is actually the definition of a pole? This review discusses the possible common denominators for growth and division of distinct and similar bacterial species.
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Affiliation(s)
- Tanneke den Blaauwen
- Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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50
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Borišek J, Pintar S, Ogrizek M, Turk D, Perdih A, Novič M. A Water-Assisted Catalytic Mechanism in Glycoside Hydrolases Demonstrated on the Staphylococcus aureus Autolysin E. ACS Catal 2018. [DOI: 10.1021/acscatal.8b01064] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Jure Borišek
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Sara Pintar
- Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
- Jozef Stefan International Postgraduate School, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Mitja Ogrizek
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Dušan Turk
- Department of Biochemistry, Molecular and Structural Biology, Jozef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
- Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins, Jamova cesta 39, SI-1000 Ljubljana, Slovenia
| | - Andrej Perdih
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
| | - Marjana Novič
- National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia
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