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Conti P, Lazzaro LM, Longo F, Lenzo F, Giardina A, Fortuna SA, Stefani S, Campanile F. Unveiling the Relationship between Ceftobiprole and High-Molecular-Mass (HMM) Penicillin-Binding Proteins (PBPs) in Enterococcus faecalis. Antibiotics (Basel) 2024; 13:65. [PMID: 38247624 PMCID: PMC10812503 DOI: 10.3390/antibiotics13010065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 12/30/2023] [Accepted: 01/06/2024] [Indexed: 01/23/2024] Open
Abstract
Low-affinity PBP4, historically linked to penicillin resistance in Enterococcus faecalis, may still have affinity for novel cephalosporins. Ceftobiprole (BPR) is a common therapeutic choice, even with PBP4-related overexpression and amino acid substitution due to mutations. Our study aims to explore the interaction between BPR and High-Molecular-Mass (HMM) low-reactive PBPs in Penicillin-Resistant-Ampicillin-Susceptible/Ceftobiprole Non-Susceptible (PRAS/BPR-NS) E. faecalis clinical isolates. We conducted competition assays examining class A and B HMM PBPs from four PRAS/BPR-NS E. faecalis strains using purified membrane proteins and fluorescent penicillin (Bocillin FL), in treated and untreated conditions. Interaction strength was assessed calculating the 50% inhibitory concentration (IC50) values for ceftobiprole, by analyzing fluorescence intensity trends. Due to its low affinity, PBP4 did not display significant acylation among all strains. Moreover, both PBP1a and PBP1b showed a similar insensitivity trend. Conversely, other PBPs showed IC50 values ranging from 1/2-fold to 4-fold MICs. Upon higher BPR concentrations, increased percentages of PBP4 inhibition were observed in all strains. Our results support the hypothesis that PBP4 is necessary but not sufficient for BPR resistance, changing the paradigm for enterococcal cephalosporin resistance. We hypothesize that cooperation between class B PBP4 and at least one bifunctional class A PBP could be required to synthesize peptidoglycan and promote growth.
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Affiliation(s)
- Paola Conti
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
- Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
| | - Lorenzo Mattia Lazzaro
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
| | - Fabio Longo
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
- Department of Public Health and Pediatrics, University of Torino, 10126 Turin, Italy
| | - Federica Lenzo
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
| | - Alessandra Giardina
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
| | - Sebastiano Alberto Fortuna
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
| | - Floriana Campanile
- Department of Biomedical and Biotechnological Sciences (BIOMETEC), Section of Microbiology, University of Catania, 95123 Catania, Italy; (P.C.); (L.M.L.); (F.L.); (F.L.); (A.G.); (S.A.F.); (S.S.)
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Models versus pathogens: how conserved is the FtsZ in bacteria? Biosci Rep 2023; 43:232502. [PMID: 36695643 PMCID: PMC9939409 DOI: 10.1042/bsr20221664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 01/10/2023] [Accepted: 01/25/2023] [Indexed: 01/26/2023] Open
Abstract
Combating anti-microbial resistance by developing alternative strategies is the need of the hour. Cell division, particularly FtsZ, is being extensively studied for its potential as an alternative target for anti-bacterial therapy. Bacillus subtilis and Escherichia coli are the two well-studied models for research on FtsZ, the leader protein of the cell division machinery. As representatives of gram-positive and gram-negative bacteria, respectively, these organisms have provided an extensive outlook into the process of cell division in rod-shaped bacteria. However, research on other shapes of bacteria, like cocci and ovococci, lags behind that of model rods. Even though most regions of FtsZ show sequence and structural conservation throughout bacteria, the differences in FtsZ functioning and interacting partners establish several different modes of division in different bacteria. In this review, we compare the features of FtsZ and cell division in the model rods B. subtilis and E. coli and the four pathogens: Staphylococcus aureus, Streptococcus pneumoniae, Mycobacterium tuberculosis, and Pseudomonas aeruginosa. Reviewing several recent articles on these pathogenic bacteria, we have highlighted the functioning of FtsZ, the unique roles of FtsZ-associated proteins, and the cell division processes in them. Further, we provide a detailed look at the anti-FtsZ compounds discovered and their target bacteria, emphasizing the need for elucidation of the anti-FtsZ mechanism of action in different bacteria. Current challenges and opportunities in the ongoing journey of identifying potent anti-FtsZ drugs have also been described.
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A multiomics analysis of direct interkingdom dynamics between influenza A virus and Streptococcus pneumoniae uncovers host-independent changes to bacterial virulence fitness. PLoS Pathog 2022; 18:e1011020. [PMID: 36542660 PMCID: PMC9815659 DOI: 10.1371/journal.ppat.1011020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/05/2023] [Accepted: 11/22/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND For almost a century, it has been recognized that influenza A virus (IAV) infection can promote the development of secondary bacterial infections (SBI) mainly caused by Streptococcus pneumoniae (Spn). Recent observations have shown that IAV is able to directly bind to the surface of Spn. To gain a foundational understanding of how direct IAV-Spn interaction alters bacterial biological fitness we employed combinatorial multiomic and molecular approaches. RESULTS Here we show IAV significantly remodels the global transcriptome, proteome and phosphoproteome profiles of Spn independently of host effectors. We identified Spn surface proteins that interact with IAV proteins (hemagglutinin, nucleoprotein, and neuraminidase). In addition, IAV was found to directly modulate expression of Spn virulence determinants such as pneumococcal surface protein A, pneumolysin, and factors associated with antimicrobial resistance among many others. Metabolic pathways were significantly altered leading to changes in Spn growth rate. IAV was also found to drive Spn capsule shedding and the release of pneumococcal surface proteins. Released proteins were found to be involved in evasion of innate immune responses and actively reduced human complement hemolytic and opsonizing activity. IAV also led to phosphorylation changes in Spn proteins associated with metabolism and bacterial virulence. Validation of proteomic data showed significant changes in Spn galactose and glucose metabolism. Furthermore, supplementation with galactose rescued bacterial growth and promoted bacterial invasion, while glucose supplementation led to enhanced pneumolysin production and lung cell apoptosis. CONCLUSIONS Here we demonstrate that IAV can directly modulate Spn biology without the requirement of host effectors and support the notion that inter-kingdom interactions between human viruses and commensal pathobionts can promote bacterial pathogenesis and microbiome dysbiosis.
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Lamanna MM, Manzoor I, Joseph M, Ye ZA, Benedet M, Zanardi A, Ren Z, Wang X, Massidda O, Tsui HT, Winkler ME. Roles of RodZ and class A PBP1b in the assembly and regulation of the peripheral peptidoglycan elongasome in ovoid-shaped cells of Streptococcus pneumoniae D39. Mol Microbiol 2022; 118:336-368. [PMID: 36001060 PMCID: PMC9804626 DOI: 10.1111/mmi.14969] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 01/17/2023]
Abstract
RodZ of rod-shaped bacteria functions to link MreB filaments to the Rod peptidoglycan (PG) synthase complex that moves circumferentially perpendicular to the long cell axis, creating hoop-like sidewall PG. Ovoid-shaped bacteria, such as Streptococcus pneumoniae (pneumococcus; Spn) that lack MreB, use a different modality for peripheral PG elongation that emanates from the midcell of dividing cells. Yet, S. pneumoniae encodes a RodZ homolog similar to RodZ in rod-shaped bacteria. We show here that the helix-turn-helix and transmembrane domains of RodZ(Spn) are essential for growth at 37°C. ΔrodZ mutations are suppressed by Δpbp1a, mpgA(Y488D), and ΔkhpA mutations that suppress ΔmreC, but not ΔcozE. Consistent with a role in PG elongation, RodZ(Spn) co-localizes with MreC and aPBP1a throughout the cell cycle and forms complexes and interacts with PG elongasome proteins and regulators. Depletion of RodZ(Spn) results in aberrantly shaped, non-growing cells and mislocalization of elongasome proteins MreC, PBP2b, and RodA. Moreover, Tn-seq reveals that RodZ(Spn), but not MreCD(Spn), displays a specific synthetic-viable genetic relationship with aPBP1b, whose function is unknown. We conclude that RodZ(Spn) acts as a scaffolding protein required for elongasome assembly and function and that aPBP1b, like aPBP1a, plays a role in elongasome regulation and possibly peripheral PG synthesis.
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Affiliation(s)
- Melissa M. Lamanna
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Irfan Manzoor
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Merrin Joseph
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Ziyun A. Ye
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Mattia Benedet
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Alessia Zanardi
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Zhongqing Ren
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Xindan Wang
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Orietta Massidda
- Department of Cellular, Computational and Integrative Biology (CIBIO)University of TrentoTrentoItaly
| | - Ho‐Ching T. Tsui
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
| | - Malcolm E. Winkler
- Department of BiologyIndiana University BloomingtonBloomingtonIndianaUSA
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5
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Jiménez-Jiménez C, Moreno VM, Vallet-Regí M. Bacteria-Assisted Transport of Nanomaterials to Improve Drug Delivery in Cancer Therapy. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:288. [PMID: 35055305 PMCID: PMC8781131 DOI: 10.3390/nano12020288] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/08/2022] [Accepted: 01/11/2022] [Indexed: 12/12/2022]
Abstract
Currently, the design of nanomaterials for the treatment of different pathologies is presenting a major impact on biomedical research. Thanks to this, nanoparticles represent a successful strategy for the delivery of high amounts of drugs for the treatment of cancer. Different nanosystems have been designed to combat this pathology. However, the poor penetration of these nanomaterials into the tumor tissue prevents the drug from entering the inner regions of the tumor. Some bacterial strains have self-propulsion and guiding capacity thanks to their flagella. They also have a preference to accumulate in certain tumor regions due to the presence of different chemo-attractants factors. Bioconjugation reactions allow the binding of nanoparticles in living systems, such as cells or bacteria, in a simple way. Therefore, bacteria are being used as a transport vehicle for nanoparticles, facilitating their penetration and the subsequent release of the drug inside the tumor. This review would summarize the literature on the anchoring methods of diverse nanosystems in bacteria and, interestingly, their advantages and possible applications in cancer therapy.
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Affiliation(s)
- Carla Jiménez-Jiménez
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, 28040 Madrid, Spain;
| | - Víctor M. Moreno
- Departamento de Química en Ciencias Farmacéuticas, Facultad de Farmacia, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria, Hospital 12 de Octubre i+12, 28040 Madrid, Spain;
| | - María Vallet-Regí
- CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, 28040 Madrid, Spain;
- Departamento de Química en Ciencias Farmacéuticas, Facultad de Farmacia, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria, Hospital 12 de Octubre i+12, 28040 Madrid, Spain;
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6
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Briggs NS, Bruce KE, Naskar S, Winkler ME, Roper DI. The Pneumococcal Divisome: Dynamic Control of Streptococcus pneumoniae Cell Division. Front Microbiol 2021; 12:737396. [PMID: 34737730 PMCID: PMC8563077 DOI: 10.3389/fmicb.2021.737396] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/15/2021] [Indexed: 12/14/2022] Open
Abstract
Cell division in Streptococcus pneumoniae (pneumococcus) is performed and regulated by a protein complex consisting of at least 14 different protein elements; known as the divisome. Recent findings have advanced our understanding of the molecular events surrounding this process and have provided new understanding of the mechanisms that occur during the division of pneumococcus. This review will provide an overview of the key protein complexes and how they are involved in cell division. We will discuss the interaction of proteins in the divisome complex that underpin the control mechanisms for cell division and cell wall synthesis and remodelling that are required in S. pneumoniae, including the involvement of virulence factors and capsular polysaccharides.
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Affiliation(s)
- Nicholas S. Briggs
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Kevin E. Bruce
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - Souvik Naskar
- Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Malcolm E. Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, United States
| | - David I. Roper
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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7
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Power AL, Barber DG, Groenhof SRM, Wagley S, Liu P, Parker DA, Love J. The Application of Imaging Flow Cytometry for Characterisation and Quantification of Bacterial Phenotypes. Front Cell Infect Microbiol 2021; 11:716592. [PMID: 34368019 PMCID: PMC8335544 DOI: 10.3389/fcimb.2021.716592] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 07/08/2021] [Indexed: 12/25/2022] Open
Abstract
Bacteria modify their morphology in response to various factors including growth stage, nutrient availability, predation, motility and long-term survival strategies. Morphological changes may also be associated with specific physiological phenotypes such as the formation of dormant or persister cells in a “viable but non-culturable” (VBNC) state which frequently display different shapes and size compared to their active counterparts. Such dormancy phenotypes can display various degrees of tolerance to antibiotics and therefore a detailed understanding of these phenotypes is crucial for combatting chronic infections and associated diseases. Cell shape and size are therefore more than simple phenotypic characteristics; they are important physiological properties for understanding bacterial life-strategies and pathologies. However, quantitative studies on the changes to cell morphologies during bacterial growth, persister cell formation and the VBNC state are few and severely constrained by current limitations in the most used investigative techniques of flow cytometry (FC) and light or electron microscopy. In this study, we applied high-throughput Imaging Flow Cytometry (IFC) to characterise and quantify, at single-cell level and over time, the phenotypic heterogeneity and morphological changes in cultured populations of four bacterial species, Bacillus subtilis, Lactiplantibacillus plantarum, Pediococcus acidilactici and Escherichia coli. Morphologies in relation to growth stage and stress responses, cell integrity and metabolic activity were analysed. Additionally, we were able to identify and morphologically classify dormant cell phenotypes such as VBNC cells and monitor the resuscitation of persister cells in Escherichia coli following antibiotic treatment. We therefore demonstrate that IFC, with its high-throughput data collection and image capture capabilities, provides a platform by which a detailed understanding of changes in bacterial phenotypes and their physiological implications may be accurately monitored and quantified, leading to a better understanding of the role of phenotypic heterogeneity in the dynamic microbiome.
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Affiliation(s)
- Ann L Power
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Daniel G Barber
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Sophie R M Groenhof
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Sariqa Wagley
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Ping Liu
- Shell International Exploration & Production Inc., Westhollow Technology Center, Houston, TX, United States
| | - David A Parker
- Shell International Exploration & Production Inc., Westhollow Technology Center, Houston, TX, United States
| | - John Love
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
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Cell wall polysaccharides of Gram positive ovococcoid bacteria and their role as bacteriophage receptors. Comput Struct Biotechnol J 2021; 19:4018-4031. [PMID: 34377367 PMCID: PMC8327497 DOI: 10.1016/j.csbj.2021.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/23/2022] Open
Abstract
Gram-positive bacterial cell walls are characterised by the presence of a thick peptidoglycan layer which provides protection from extracellular stresses, maintains cell integrity and determines cell morphology, while it also serves as a foundation to anchor a number of crucial polymeric structures. For ovococcal species, including streptococci, enterococci and lactococci, such structures are represented by rhamnose-containing cell wall polysaccharides, which at least in some instances appear to serve as a functional replacement for wall teichoic acids. The biochemical composition of several streptococcal, lactococcal and enterococcal rhamnose-containing cell wall polysaccharides have been elucidated, while associated functional genomic analyses have facilitated the proposition of models for individual biosynthetic pathways. Here, we review the genomic loci which encode the enzymatic machinery to produce rhamnose-containing, cell wall-associated polysaccharide (Rha cwps) structures of the afore-mentioned ovococcal bacteria with particular emphasis on gene content, biochemical structure and common biosynthetic steps. Furthermore, we discuss the role played by these saccharidic polymers as receptors for bacteriophages and the important role phages play in driving Rha cwps diversification and evolution.
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Trouve J, Zapun A, Arthaud C, Durmort C, Di Guilmi AM, Söderström B, Pelletier A, Grangeasse C, Bourgeois D, Wong YS, Morlot C. Nanoscale dynamics of peptidoglycan assembly during the cell cycle of Streptococcus pneumoniae. Curr Biol 2021; 31:2844-2856.e6. [PMID: 33989523 DOI: 10.1016/j.cub.2021.04.041] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 03/09/2021] [Accepted: 04/16/2021] [Indexed: 12/15/2022]
Abstract
Dynamics of cell elongation and septation are key determinants of bacterial morphogenesis. These processes are intimately linked to peptidoglycan synthesis performed by macromolecular complexes called the elongasome and the divisome. In rod-shaped bacteria, cell elongation and septation, which are dissociated in time and space, have been well described. By contrast, in ovoid-shaped bacteria, the dynamics and relationships between these processes remain poorly understood because they are concomitant and confined to a nanometer-scale annular region at midcell. Here, we set up a metabolic peptidoglycan labeling approach using click chemistry to image peptidoglycan synthesis by single-molecule localization microscopy in the ovoid bacterium Streptococcus pneumoniae. Our nanoscale-resolution data reveal spatiotemporal features of peptidoglycan assembly and fate along the cell cycle and provide geometrical parameters that we used to construct a morphogenesis model of the ovoid cell. These analyses show that septal and peripheral peptidoglycan syntheses first occur within a single annular region that later separates in two concentric regions and that elongation persists after septation is completed. In addition, our data reveal that freshly synthesized peptidoglycan is remodeled all along the cell cycle. Altogether, our work provides evidence that septal peptidoglycan is synthesized from the beginning of the cell cycle and is constantly remodeled through cleavage and insertion of material at its periphery. The ovoid-cell morphogenesis would thus rely on the relative dynamics between peptidoglycan synthesis and cleavage rather than on the existence of two distinct successive phases of peripheral and septal synthesis.
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Affiliation(s)
- Jennyfer Trouve
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France
| | - André Zapun
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France
| | | | - Claire Durmort
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France
| | | | - Bill Söderström
- The ithree institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; Structural Cellular Biology Unit, Okinawa Institute of Science and Technology, 904-0495 Okinawa, Japan
| | - Anais Pelletier
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, Univ. Lyon 1, UMR 5086, Lyon 69007, France
| | - Christophe Grangeasse
- Molecular Microbiology and Structural Biochemistry (MMSB), CNRS, Univ. Lyon 1, UMR 5086, Lyon 69007, France
| | | | | | - Cecile Morlot
- Univ. Grenoble Alpes, CNRS, CEA, IBS, 38000 Grenoble, France.
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EloR interacts with the lytic transglycosylase MltG at midcell in Streptococcus pneumoniae R6. J Bacteriol 2021; 203:JB.00691-20. [PMID: 33558392 PMCID: PMC8092159 DOI: 10.1128/jb.00691-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The ellipsoid shape of Streptococcus pneumoniae is determined by the synchronized actions of the elongasome and the divisome, which have the task of creating a protective layer of peptidoglycan (PG) enveloping the cell membrane. The elongasome is necessary for expanding PG in the longitudinal direction whereas the divisome synthesizes the PG that divides one cell into two. Although there is still little knowledge about how these two modes of PG synthesis are coordinated, it was recently discovered that two RNA-binding proteins called EloR and KhpA are part of a novel regulatory pathway controlling elongation in S. pneumoniae EloR and KhpA form a complex that work closely with the Ser/Thr kinase StkP to regulate cell elongation. Here, we have further explored how this regulation occur. EloR/KhpA is found at midcell, a localization fully dependent on EloR. Using a bacterial two-hybrid assay we probed EloR against several elongasome proteins and found an interaction with the lytic transglycosylase homolog MltG. By using EloR as bait in immunoprecipitation assays, MltG was pulled down confirming that they are part of the same protein complex. Fluorescent microscopy demonstrated that the Jag domain of EloR is essential for EloR's midcell localization and its interaction with MltG. Since MltG is found at midcell independent of EloR, our results suggest that MltG is responsible for recruitment of the EloR/KhpA complex to the division zone to regulate cell elongation.Importance Bacterial cell division has been a successful target for antimicrobial agents for decades. How different pathogens regulate cell division is, however, poorly understood. To fully exploit the potential for future antibiotics targeting cell division, we need to understand the details of how the bacteria regulate and construct cell wall during this process. Here we have revealed that the newly identified EloR/KhpA complex, regulating cell elongation in S. pneumoniae, forms a complex with the essential peptidoglycan transglycosylase MltG at midcell. EloR, KhpA and MltG are conserved among many bacterial species and the EloR/KhpA/MltG regulatory pathway is most likely a common mechanism employed by many Gram-positive bacteria to coordinate cell elongation and septation.
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11
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Streptococcus suis MsmK: Novel Cell Division Protein Interacting with FtsZ and Maintaining Cell Shape. mSphere 2021; 6:6/2/e00119-21. [PMID: 33731468 PMCID: PMC8546688 DOI: 10.1128/msphere.00119-21] [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] [Indexed: 11/29/2022] Open
Abstract
Bacteria of different shapes have adopted distinct mechanisms to faithfully coordinate morphogenesis and segregate their chromosomes prior to cell division. Despite recent focuses and advances, the mechanism of cell division in ovococci remains largely unknown. Streptococcus suis, a major zoonotic pathogen that causes problems in human health and in the global swine industry, is an elongated and ellipsoid bacterium that undergoes successive parallel splitting perpendicular to its long axis. Studies on cell cycle processes in this bacterium are limited. Here, we report that MsmK (multiple sugar metabolism protein K), an ATPase that contributes to the transport of multiple carbohydrates, has a novel role as a cell division protein in S. suis. MsmK can display ATPase and GTPase activities, interact with FtsZ via the N terminus of MsmK, and promote the bundling of FtsZ protofilaments in a GTP-dependent manner in vitro. Deletion of the C-terminal region or the Walker A or B motif affects the affinity between MsmK and FtsZ and decreases the ability of MsmK to promote FtsZ protofilament bundling. MsmK can form a complex with FtsZ in vivo, and its absence is not lethal but results in long chains and short, occasionally anuclear daughter cells. Superresolution microscopy revealed that the lack of MsmK in cells leads to normal septal peptidoglycan walls in mother cells but disturbed cell elongation and peripheral peptidoglycan synthesis. In summary, MsmK is a novel cell division protein that maintains cell shape and is involved in the synthesis of the peripheral cell wall. IMPORTANCE Bacterial cell division is a highly ordered process regulated in time and space and is a potential target for the development of antimicrobial drugs. Bacteria of distinct shapes depend on different cell division mechanisms, but the mechanisms used by ovococci remain largely unknown. Here, we focused on the zoonotic pathogen Streptococcus suis and identified a novel cell division protein named MsmK, which acts as an ATPase of the ATP-binding cassette-type carbohydrate transport system. MsmK has GTPase and ATPase activities. In vitro protein assays showed that MsmK interacts with FtsZ and promotes FtsZ protofilament bundling that relies on GTP. Superresolution microscopy revealed that MsmK maintains cell shape and is involved in peripheral peptidoglycan synthesis. Knowledge of the multiple functions of MsmK may broaden our understanding of known cell division processes. Further studies in this area will elucidate how bacteria can faithfully and continually multiply in a constantly changing environment.
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Perez AJ, Boersma MJ, Bruce KE, Lamanna MM, Shaw SL, Tsui HCT, Taguchi A, Carlson EE, VanNieuwenhze MS, Winkler ME. Organization of peptidoglycan synthesis in nodes and separate rings at different stages of cell division of Streptococcus pneumoniae. Mol Microbiol 2020; 115:1152-1169. [PMID: 33269494 DOI: 10.1111/mmi.14659] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 11/28/2020] [Indexed: 12/15/2022]
Abstract
Bacterial peptidoglycan (PG) synthesis requires strict spatiotemporal organization to reproduce specific cell shapes. In ovoid-shaped Streptococcus pneumoniae (Spn), septal and peripheral (elongation) PG synthesis occur simultaneously at midcell. To uncover the organization of proteins and activities that carry out these two modes of PG synthesis, we examined Spn cells vertically oriented onto their poles to image the division plane at the high lateral resolution of 3D-SIM (structured-illumination microscopy). Labeling with fluorescent D-amino acids (FDAA) showed that areas of new transpeptidase (TP) activity catalyzed by penicillin-binding proteins (PBPs) separate into a pair of concentric rings early in division, representing peripheral PG (pPG) synthesis (outer ring) and the leading-edge (inner ring) of septal PG (sPG) synthesis. Fluorescently tagged PBP2x or FtsZ locate primarily to the inner FDAA-marked ring, whereas PBP2b and FtsX remain in the outer ring, suggesting roles in sPG or pPG synthesis, respectively. Pulses of FDAA labeling revealed an arrangement of separate regularly spaced "nodes" of TP activity around the division site of predivisional cells. Tagged PBP2x, PBP2b, and FtsX proteins also exhibited nodal patterns with spacing comparable to that of FDAA labeling. Together, these results reveal new aspects of spatially ordered PG synthesis in ovococcal bacteria during cell division.
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Affiliation(s)
- Amilcar J Perez
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Michael J Boersma
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Kevin E Bruce
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Melissa M Lamanna
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Sidney L Shaw
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Ho-Ching T Tsui
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
| | - Atsushi Taguchi
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Erin E Carlson
- Department of Chemistry, University of Minnesota, Minneapolis, MN, USA
| | | | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
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13
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Nachtigall C, Vogel C, Rohm H, Jaros D. How Capsular Exopolysaccharides Affect Cell Surface Properties of Lactic Acid Bacteria. Microorganisms 2020; 8:E1904. [PMID: 33266168 PMCID: PMC7759885 DOI: 10.3390/microorganisms8121904] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/11/2022] Open
Abstract
Some lactic acid bacteria are able to produce exopolysaccharides that, based on localization, can be distinguished in free and capsular or cell-bound exopolysaccharides (CPS). Up to now, the former were the focus of current research, mainly because of the technofunctional benefits they exhibit on fermented dairy products. On the other hand, CPS affect the surface properties of bacteria cells and thus also the textural properties of fermented foods, but data are very scarce. As the cell surface properties are strongly strain dependent, we present a new approach to investigate the impact of CPS on cell surface hydrophobicity and moisture load. CPS positive and negative Streptococcus thermophilus and Weissella cibaria were subjected to ultrasonication suitable to detach CPS without cell damage. The success of the method was verified by scanning electron and light microscopy as well as by cultivation experiments. Before applying ultrasonication cells with CPS exhibiting an increased hydrophilic character, enhanced moisture load, and faster water adsorption compared to the cells after CPS removal, emphasizing the importance of CPS on the textural properties of fermented products. The ultrasonic treatment did not alter the cell surface properties of the CPS negative strains.
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Affiliation(s)
- Carsten Nachtigall
- Institute of Natural Materials Technology, Technische Universität Dresden, 01062 Dresden, Germany; (H.R.); (D.J.)
| | - Cordula Vogel
- Institute of Soil Science and Site Ecology, Technische Universität Dresden, 01062 Dresden, Germany;
| | - Harald Rohm
- Institute of Natural Materials Technology, Technische Universität Dresden, 01062 Dresden, Germany; (H.R.); (D.J.)
| | - Doris Jaros
- Institute of Natural Materials Technology, Technische Universität Dresden, 01062 Dresden, Germany; (H.R.); (D.J.)
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14
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Physical, Thermal, and Antibacterial Effects of Active Essential Oils with Potential for Biomedical Applications Loaded onto Cellulose Acetate/Polycaprolactone Wet-Spun Microfibers. Biomolecules 2020; 10:biom10081129. [PMID: 32751893 PMCID: PMC7465996 DOI: 10.3390/biom10081129] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/20/2020] [Accepted: 07/30/2020] [Indexed: 12/14/2022] Open
Abstract
New approaches to deal with the growing concern associated with antibiotic-resistant bacteria are emerging daily. Essential oils (EOs) are natural antimicrobial substances with great potential to mitigate this situation. However, their volatile nature, in their liquid-free form, has restricted their generalized application in biomedicine. Here, we propose the use of cellulose acetate (CA)/polycaprolactone (PCL) wet-spun fibers as potential delivery platforms of selected EOs to fight infections caused by Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Twenty EOs were selected and screened for their minimal inhibitory concentration (MIC), using the antibiotic ampicillin as positive control. The cinnamon leaf oil (CLO), cajeput oil (CJO), and the clove oil (CO) were the most effective EOs, against the Gram-positive (MIC < 22.38 mg/mL) and the Gram-negative (MIC < 11.19 mg/mL) bacteria. Uniform microfibers were successfully wet-spun from CA/PCL with an averaged diameter of 53.9 ± 4.5 µm, and then modified by immersion with CLO, CJO and CO at 2 × MIC value. EOs incorporation was confirmed by UV-visible spectroscopy, Fourier-transformed infrared spectroscopy, and thermal gravimetric analysis. However, while microfibers contained ampicillin at MIC (control) after the 72 h modification, the CLO, CO and CJO-loaded fibers registered ≈ 14%, 66%, and 76% of their MIC value, respectively. Data showed that even at small amounts the EO-modified microfibers were effective against the tested bacteria, both by killing bacteria more quickly or by disrupting more easily their cytoplasmic membrane than ampicillin. Considering the amount immobilized, CLO-modified fibers were deemed the most effective from the EOs group. These results indicate that CA/PCL microfibers loaded with EOs can be easily produced with increased antibacterial action, envisioning their use as scaffolding materials for the treatment of infections.
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15
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Penicillin-binding proteins regulate multiple steps in the polarized cell division process of Chlamydia. Sci Rep 2020; 10:12588. [PMID: 32724139 PMCID: PMC7387471 DOI: 10.1038/s41598-020-69397-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 07/08/2020] [Indexed: 12/26/2022] Open
Abstract
Chlamydia trachomatis serovar L2 and Chlamydia muridarum, which do not express FtsZ, undergo polarized cell division. During division, peptidoglycan assembles at the pole of dividing Chlamydia trachomatis cells where daughter cell formation occurs, and peptidoglycan regulates at least two distinct steps in the polarized division of Chlamydia trachomatis and Chlamydia muridarum. Cells treated with inhibitors that prevent peptidoglycan synthesis or peptidoglycan crosslinking by penicillin-binding protein 2 (PBP2) are unable to initiate polarized division, while cells treated with inhibitors that prevent peptidoglycan crosslinking by penicillin-binding protein 3 (PBP3/FtsI) initiate polarized division, but the process arrests at an early stage of daughter cell growth. Consistent with their distinct roles in polarized division, peptidoglycan organization is different in cells treated with PBP2 and PBP3-specific inhibitors. Our analyses indicate that the sequential action of PBP2 and PBP3 drives changes in peptidoglycan organization that are essential for the polarized division of these obligate intracellular bacteria. Furthermore, the roles we have characterized for PBP2 and PBP3 in regulating specific steps in chlamydial cell division have not been described in other bacteria.
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16
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Tavares TD, Antunes JC, Padrão J, Ribeiro AI, Zille A, Amorim MTP, Ferreira F, Felgueiras HP. Activity of Specialized Biomolecules against Gram-Positive and Gram-Negative Bacteria. Antibiotics (Basel) 2020; 9:E314. [PMID: 32526972 PMCID: PMC7344598 DOI: 10.3390/antibiotics9060314] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 11/24/2022] Open
Abstract
The increased resistance of bacteria against conventional pharmaceutical solutions, the antibiotics, has raised serious health concerns. This has stimulated interest in the development of bio-based therapeutics with limited resistance, namely, essential oils (EOs) or antimicrobial peptides (AMPs). This study envisaged the evaluation of the antimicrobial efficacy of selected biomolecules, namely LL37, pexiganan, tea tree oil (TTO), cinnamon leaf oil (CLO) and niaouli oil (NO), against four bacteria commonly associated to nosocomial infections: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. The antibiotic vancomycin and silver nanoparticles (AgNPs) were used as control compounds for comparison purposes. The biomolecules were initially screened for their antibacterial efficacy using the agar-diffusion test, followed by the determination of minimal inhibitory concentrations (MICs), kill-time kinetics and the evaluation of the cell morphology upon 24 h exposure. All agents were effective against the selected bacteria. Interestingly, the AgNPs required a higher concentration (4000-1250 µg/mL) to induce the same effects as the AMPs (500-7.8 µg/mL) or EOs (365.2-19.7 µg/mL). Pexiganan and CLO were the most effective biomolecules, requiring lower concentrations to kill both Gram-positive and Gram-negative bacteria (62.5-7.8 µg/mL and 39.3-19.7 µg/mL, respectively), within a short period of time (averaging 2 h 15 min for all bacteria). Most biomolecules apparently disrupted the bacteria membrane stability due to the observed cell morphology deformation and by effecting on the intracellular space. AMPs were observed to induce morphological deformations and cellular content release, while EOs were seen to split and completely envelope bacteria. Data unraveled more of the potential of these new biomolecules as replacements for the conventional antibiotics and allowed us to take a step forward in the understanding of their mechanisms of action against infection-related bacteria.
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Affiliation(s)
| | | | | | | | | | | | | | - Helena P. Felgueiras
- Centre for Textile Science and Technology (2C2T), Department of Textile Engineering, University of Minho, Campus of Azurém, 4800-058 Guimarães, Portugal; (T.D.T.); (J.C.A.); (J.P.); (A.I.R.); (A.Z.); (M.T.P.A.); (F.F.)
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17
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Evolution of Life on Earth: tRNA, Aminoacyl-tRNA Synthetases and the Genetic Code. Life (Basel) 2020; 10:life10030021. [PMID: 32131473 PMCID: PMC7151597 DOI: 10.3390/life10030021] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/13/2020] [Accepted: 02/27/2020] [Indexed: 02/07/2023] Open
Abstract
Life on Earth and the genetic code evolved around tRNA and the tRNA anticodon. We posit that the genetic code initially evolved to synthesize polyglycine as a cross-linking agent to stabilize protocells. We posit that the initial amino acids to enter the code occupied larger sectors of the code that were then invaded by incoming amino acids. Displacements of amino acids follow selection rules. The code sectored from a glycine code to a four amino acid code to an eight amino acid code to an ~16 amino acid code to the standard 20 amino acid code with stops. The proposed patterns of code sectoring are now most apparent from patterns of aminoacyl-tRNA synthetase evolution. The Elongation Factor-Tu GTPase anticodon-codon latch that checks the accuracy of translation appears to have evolved at about the eight amino acid to ~16 amino acid stage. Before evolution of the EF-Tu latch, we posit that both the 1st and 3rd anticodon positions were wobble positions. The genetic code evolved via tRNA charging errors and via enzymatic modifications of amino acids joined to tRNAs, followed by tRNA and aminoacyl-tRNA synthetase differentiation. Fidelity mechanisms froze the code by inhibiting further innovation.
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18
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The evolution of spherical cell shape; progress and perspective. Biochem Soc Trans 2020; 47:1621-1634. [PMID: 31829405 PMCID: PMC6925525 DOI: 10.1042/bst20180634] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 11/06/2019] [Accepted: 11/11/2019] [Indexed: 01/29/2023]
Abstract
Bacterial cell shape is a key trait governing the extracellular and intracellular factors of bacterial life. Rod-like cell shape appears to be original which implies that the cell wall, division, and rod-like shape came together in ancient bacteria and that the myriad of shapes observed in extant bacteria have evolved from this ancestral shape. In order to understand its evolution, we must first understand how this trait is actively maintained through the construction and maintenance of the peptidoglycan cell wall. The proteins that are primarily responsible for cell shape are therefore the elements of the bacterial cytoskeleton, principally FtsZ, MreB, and the penicillin-binding proteins. MreB is particularly relevant in the transition between rod-like and spherical cell shape as it is often (but not always) lost early in the process. Here we will highlight what is known of this particular transition in cell shape and how it affects fitness before giving a brief perspective on what will be required in order to progress the field of cell shape evolution from a purely mechanistic discipline to one that has the perspective to both propose and to test reasonable hypotheses regarding the ecological drivers of cell shape change.
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19
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Abstract
Transfer RNA (tRNA) is the central intellectual property in the evolution of life on Earth. tRNA evolved from repeats and inverted repeats of known sequence. The anticodon and the T stem-loop-stems are homologs with significant conserved sequence identity. A number of models have been advanced to explain tRNA evolution. No 2-minihelix model or accretion model (built a stem at a time) can be correct, in part because of anticodon and T stem-loop-stem identity. Only a 3-minihelix model is adequate.
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20
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Hsu YP, Booher G, Egan A, Vollmer W, VanNieuwenhze MS. d-Amino Acid Derivatives as in Situ Probes for Visualizing Bacterial Peptidoglycan Biosynthesis. Acc Chem Res 2019; 52:2713-2722. [PMID: 31419110 DOI: 10.1021/acs.accounts.9b00311] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The bacterial cell wall is composed of membrane layers and a rigid yet flexible scaffold called peptidoglycan (PG). PG provides mechanical strength to enable bacteria to resist damage from the environment and lysis due to high internal turgor. PG also has a critical role in dictating bacterial cell morphology. The essential nature of PG for bacterial propagation, as well as its value as an antibiotic target, has led to renewed interest in the study of peptidoglycan biosynthesis. However, significant knowledge gaps remain that must be addressed before a clear understanding of peptidoglycan synthesis and dynamics is realized. For example, the enzymes involved in the PG biosynthesis pathway have not been fully characterized. Our understanding of PG biosynthesis has been frequently revamped by the discovery of novel enzymes or newly characterized functions of known enzymes. In addition, we do not clearly know how the respective activities of these enzymes are coordinated with each other and how they control the spatial and temporal dynamics of PG synthesis. The emergence of molecular probes and imaging techniques has significantly advanced the study PG synthesis and modification. Prior efforts utilized the specificity of PG-targeting antibiotics and proteins to develop PG-specific probes, such as fluorescent vancomycin and fluorescent wheat germ agglutinin. However, these probes suffer from limitations due to toxic effects toward bacterial cells and poor membrane permeability. To address these issues, we designed and introduced a family of novel molecular probes, fluorescent d-amino acids (FDAAs), which are covalently incorporated into PG through the activities of endogenous bacterial transpeptidases. Their high biocompatibility and PG specificity have made them powerful tools for labeling peptidoglycan. In addition, their enzyme-mediated incorporation faithfully reflects the activity of PG synthases, providing a direct in situ method for studying PG formation during the bacterial life cycle. In this Account, we describe our efforts directed at the development of FDAAs and their derivatives. These probes have enabled for the first time the ability to visualize PG synthesis in live bacterial cells and in real time. We summarize experimental evidence for FDAA incorporation into PG and the enzyme-mediated incorporation pathway. We demonstrate various applications of FDAAs, including bacterial morphology analyses, PG growth model studies, investigation of PG-enzyme correlation, in vitro PG synthase activity assays, and antibiotic inhibition tests. Finally, we discuss the current limitations of the probes and our ongoing efforts to improve them. We are confident that these probes will prove to be valuable tools that will enable the discovery of new antibiotic targets and expand the available arsenal directed at the public health threat posed by antibiotic resistance.
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Affiliation(s)
- Yen-Pang Hsu
- Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Simon Hall 001, 212 South Hawthorne Drive, Bloomington, Indiana 47405, United States
| | - Garrett Booher
- Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Simon Hall 001, 212 South Hawthorne Drive, Bloomington, Indiana 47405, United States
| | - Alexander Egan
- The Centre for Bacterial Cell Biology, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, United Kingdom
| | - Waldemar Vollmer
- The Centre for Bacterial Cell Biology, Newcastle University, Richardson Road, Newcastle upon Tyne NE2 4AX, United Kingdom
| | - Michael S. VanNieuwenhze
- Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Simon Hall 001, 212 South Hawthorne Drive, Bloomington, Indiana 47405, United States
- Department of Chemistry, Indiana University Bloomington, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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21
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Vollmer W, Massidda O, Tomasz A. The Cell Wall of Streptococcus pneumoniae. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0018-2018. [PMID: 31172911 PMCID: PMC11026078 DOI: 10.1128/microbiolspec.gpp3-0018-2018] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Indexed: 12/13/2022] Open
Abstract
Streptococcus pneumoniae has a complex cell wall that plays key roles in cell shape maintenance, growth and cell division, and interactions with components of the human host. The peptidoglycan has a heterogeneous composition with more than 50 subunits (muropeptides)-products of several peptidoglycan-modifying enzymes. The amidation of glutamate residues in the stem peptide is needed for efficient peptide cross-linking, and peptides with a dipeptide branch prevail in some beta-lactam-resistant strains. The glycan strands are modified by deacetylation of N-acetylglucosamine residues and O-acetylation of N-acetylmuramic acid residues, and both modifications contribute to pneumococcal resistance to lysozyme. The glycan strands carry covalently attached wall teichoic acid and capsular polysaccharide. Pneumococci are unique in that the wall teichoic acid and lipoteichoic acid contain the same unusually complex repeating units decorated with phosphoryl choline residues, which anchor the choline-binding proteins. The structures of lipoteichoic acid and the attachment site of wall teichoic acid to peptidoglycan have recently been revised. During growth, pneumococci assemble their cell walls at midcell in coordinated rounds of cell elongation and division, leading to the typical ovococcal cell shape. Cell wall growth depends on the cytoskeletal FtsA and FtsZ proteins and is regulated by several morphogenesis proteins that also show patterns of dynamic localization at midcell. Some of the key regulators are phosphorylated by StkP and dephosphorylated by PhpP to facilitate robust selection of the division site and plane and to maintain cell shape.
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Affiliation(s)
- Waldemar Vollmer
- Institute for Cell and Molecular Biosciences, The Centre for Bacterial Cell Biology, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Orietta Massidda
- Department of Cellular, Computational and Integrative Biology, University of Trento, Trento, Italy
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22
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Calvez P, Jouhet J, Vié V, Durmort C, Zapun A. Lipid Phases and Cell Geometry During the Cell Cycle of Streptococcus pneumoniae. Front Microbiol 2019; 10:351. [PMID: 30936851 PMCID: PMC6432855 DOI: 10.3389/fmicb.2019.00351] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/11/2019] [Indexed: 01/31/2023] Open
Abstract
The coexistence of different lipid phases is well-known in vitro, but evidence for their presence and function in cellular membranes remains scarce. Using a combination of fluorescent lipid probes, we observe segregation of domains that suggests the coexistence of liquid and gel phases in the membrane of Streptococcus pneumoniae, where they are localized to minimize bending stress in the ellipsoid geometry defined by the cell wall. Gel phase lipids with high bending rigidity would be spontaneously organized at the equator where curvature is minimal, thus marking the future division site, while liquid phase membrane maps onto the oblong hemispheres. In addition, the membrane-bound cell wall precursor with its particular dynamic acyl chain localizes at the division site where the membrane is highly curved. We propose a complete “chicken-and-egg” model where cell geometry determines the localization of lipid phases that positions the cell division machinery, which in turn alters the localization of lamellar phases by assembling the cell wall with a specific geometry.
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Affiliation(s)
| | - Juliette Jouhet
- UMR 5168 CNRS, CEA, INRA, CEA Grenoble, Laboratoire de Physiologie Cellulaire Végétale, Bioscience and Biotechnologies Institute of Grenoble, Université Grenoble Alpes, Grenoble, France
| | - Véronique Vié
- Univ Rennes, CNRS, IPR-UMR 6251, ScanMat-UMS2001, Rennes, France
| | | | - André Zapun
- Univ. Grenoble Alpes, CNRS, CEA, IBS, Grenoble, France
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23
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Prevention of EloR/KhpA heterodimerization by introduction of site-specific amino acid substitutions renders the essential elongasome protein PBP2b redundant in Streptococcus pneumoniae. Sci Rep 2019; 9:3681. [PMID: 30842445 PMCID: PMC6403258 DOI: 10.1038/s41598-018-38386-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/27/2018] [Indexed: 12/31/2022] Open
Abstract
The RNA binding proteins EloR and KhpA are important components of the regulatory network that controls and coordinates cell elongation and division in S. pneumoniae. Loss of either protein reduces cell length, and makes the essential elongasome proteins PBP2b and RodA dispensable. It has been shown previously in formaldehyde crosslinking experiments that EloR co-precipitates with KhpA, indicating that they form a complex in vivo. In the present study, we used 3D modeling and site directed mutagenesis in combination with protein crosslinking to further study the relationship between EloR and KhpA. Protein-protein interaction studies demonstrated that KhpA forms homodimers and that KhpA in addition binds to the KH-II domain of EloR. Site directed mutagenesis identified isoleucine 61 (I61) as crucial for KhpA homodimerization. When substituting I61 with phenylalanine, KhpA lost the ability to homodimerize, while it still interacted clearly with EloR. In contrast, both homo- and heterodimerization were lost when I61 was substituted with tyrosine. By expressing these KhpA versions in S. pneumoniae, we were able to show that disruption of EloR/KhpA heterodimerization makes the elongasome redundant in S. pneumoniae. Of note, loss of KhpA homodimerization did not give rise to this phenotype, demonstrating that the EloR/KhpA complex is crucial for regulating the activity of the elongasome. In support of this conclusion, we found that localization of KhpA to the pneumococcal mid-cell region depends on its interaction with EloR. Furthermore, we found that the EloR/KhpA complex co-localizes with FtsZ throughout the cell cycle.
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24
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Schaub RE, Dillard JP. The Pathogenic Neisseria Use a Streamlined Set of Peptidoglycan Degradation Proteins for Peptidoglycan Remodeling, Recycling, and Toxic Fragment Release. Front Microbiol 2019; 10:73. [PMID: 30766523 PMCID: PMC6365954 DOI: 10.3389/fmicb.2019.00073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 01/15/2019] [Indexed: 12/26/2022] Open
Abstract
Neisseria gonorrhoeae and Neisseria meningitidis release peptidoglycan (PG) fragments from the cell as the bacteria grow. For N. gonorrhoeae these PG fragments are known to cause damage to human Fallopian tube tissue in organ culture that mimics the damage seen in patients with pelvic inflammatory disease. N. meningitidis also releases pro-inflammatory PG fragments, but in smaller amounts than those from N. gonorrhoeae. It is not yet known if PG fragment release contributes to the highly inflammatory conditions of meningitis and meningococcemia caused by N. meningitidis. Examination of the mechanisms of PG degradation and recycling identified proteins required for these processes. In comparison to the model organism E. coli, the pathogenic Neisseria have far fewer PG degradation proteins, and some of these proteins show differences in subcellular localization compared to their E. coli homologs. In particular, some N. gonorrhoeae PG degradation proteins were demonstrated to be in the outer membrane while their homologs in E. coli were found free in the periplasm or in the cytoplasm. The localization of two of these proteins was demonstrated to affect PG fragment release. Another major factor for PG fragment release is the allele of ampG. Gonococcal AmpG was found to be slightly defective compared to related PG fragment permeases, thus leading to increased release of PG. A number of additional PG-related factors affect other virulence functions in Neisseria. Endopeptidases and carboxypeptidases were found to be required for type IV pilus production and resistance to hydrogen peroxide. Also, deacetylation of PG was required for virulence of N. meningitidis as well as normal cell size. Overall, we describe the processes involved in PG degradation and recycling and how certain characteristics of these proteins influence the interactions of these pathogens with their host.
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Affiliation(s)
- Ryan E Schaub
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Joseph P Dillard
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
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25
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Pathak A, Bergstrand J, Sender V, Spelmink L, Aschtgen MS, Muschiol S, Widengren J, Henriques-Normark B. Factor H binding proteins protect division septa on encapsulated Streptococcus pneumoniae against complement C3b deposition and amplification. Nat Commun 2018; 9:3398. [PMID: 30139996 PMCID: PMC6107515 DOI: 10.1038/s41467-018-05494-w] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 07/05/2018] [Indexed: 01/20/2023] Open
Abstract
Streptococcus pneumoniae evades C3-mediated opsonization and effector functions by expressing an immuno-protective polysaccharide capsule and Factor H (FH)-binding proteins. Here we use super-resolution microscopy, mutants and functional analysis to show how these two defense mechanisms are functionally and spatially coordinated on the bacterial cell surface. We show that the pneumococcal capsule is less abundant at the cell wall septum, providing C3/C3b entry to underlying nucleophilic targets. Evasion of C3b deposition at division septa and lateral amplification underneath the capsule requires localization of the FH-binding protein PspC at division sites. Most pneumococcal strains have one PspC protein, but successful lineages in colonization and disease may have two, PspC1 and PspC2, that we show affect virulence differently. We find that spatial localization of these FH-recruiting proteins relative to division septa and capsular layer is instrumental for pneumococci to resist complement-mediated opsonophagocytosis, formation of membrane-attack complexes, and for the function as adhesins. Streptococcus pneumoniae evades the action of the complement system by expressing an immuno-protective polysaccharide capsule as well as Factor H-binding proteins. Here, Pathak et al. show that these two defence mechanisms are functionally and spatially coordinated on the bacterial cell surface.
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Affiliation(s)
- Anuj Pathak
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Jan Bergstrand
- Department Applied Physics, Royal Institute of Technology (KTH), Experimental Biomolecular Physics, SE-106 91, Stockholm, Sweden
| | - Vicky Sender
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Laura Spelmink
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Marie-Stephanie Aschtgen
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Sandra Muschiol
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Jerker Widengren
- Department Applied Physics, Royal Institute of Technology (KTH), Experimental Biomolecular Physics, SE-106 91, Stockholm, Sweden
| | - Birgitta Henriques-Normark
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden. .,Lee Kong Chian School of Medicine (LKC) and Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, 639798, Singapore. .,Department of Clinical Microbiology, Karolinska University Hospital, SE-171 76, Stockholm, Sweden.
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26
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Sutaria DS, Moya B, Green KB, Kim TH, Tao X, Jiao Y, Louie A, Drusano GL, Bulitta JB. First Penicillin-Binding Protein Occupancy Patterns of β-Lactams and β-Lactamase Inhibitors in Klebsiella pneumoniae. Antimicrob Agents Chemother 2018; 62:e00282-18. [PMID: 29712652 PMCID: PMC5971569 DOI: 10.1128/aac.00282-18] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 02/28/2018] [Indexed: 01/22/2023] Open
Abstract
Penicillin-binding proteins (PBPs) are the high-affinity target sites of all β-lactam antibiotics in bacteria. It is well known that each β-lactam covalently binds to and thereby inactivates different PBPs with various affinities. Despite β-lactams serving as the cornerstone of our therapeutic armamentarium against Klebsiella pneumoniae, PBP binding data are missing for this pathogen. We aimed to generate the first PBP binding data on 13 chemically diverse and clinically relevant β-lactams and β-lactamase inhibitors in K. pneumoniae PBP binding was determined using isolated membrane fractions from K. pneumoniae strains ATCC 43816 and ATCC 13883. Binding reactions were conducted using β-lactam concentrations from 0.0075 to 256 mg/liter (or 128 mg/liter). After β-lactam exposure, unbound PBPs were labeled by Bocillin FL. Binding affinities (50% inhibitory concentrations [IC50]) were reported as the β-lactam concentrations that half-maximally inhibited Bocillin FL binding. PBP occupancy patterns by β-lactams were consistent across both strains. Carbapenems bound to all PBPs, with PBP2 and PBP4 as the highest-affinity targets (IC50, <0.0075 mg/liter). Preferential PBP2 binding was observed by mecillinam (amdinocillin; IC50, <0.0075 mg/liter) and avibactam (IC50, 2 mg/liter). Aztreonam showed high affinity for PBP3 (IC50, 0.06 to 0.12 mg/liter). Ceftazidime bound PBP3 at low concentrations (IC50, 0.06 to 0.25 mg/liter) and PBP1a/b at higher concentrations (4 mg/liter), whereas cefepime bound PBPs 1 to 4 at more even concentrations (IC50, 0.015 to 2 mg/liter). These PBP binding data on a comprehensive set of 13 clinically relevant β-lactams and β-lactamase inhibitors in K. pneumoniae enable, for the first time, the rational design and optimization of double β-lactam and β-lactam-β-lactamase inhibitor combinations.
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Affiliation(s)
- Dhruvitkumar S Sutaria
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Bartolome Moya
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Kari B Green
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | - Tae Hwan Kim
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Xun Tao
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Yuanyuan Jiao
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Arnold Louie
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - George L Drusano
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - Jürgen B Bulitta
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, Florida, USA
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27
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David B, Duchêne MC, Haustenne GL, Pérez-Núñez D, Chapot-Chartier MP, De Bolle X, Guédon E, Hols P, Hallet B. PBP2b plays a key role in both peripheral growth and septum positioning in Lactococcus lactis. PLoS One 2018; 13:e0198014. [PMID: 29791496 PMCID: PMC5965867 DOI: 10.1371/journal.pone.0198014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/11/2018] [Indexed: 12/11/2022] Open
Abstract
Lactococcus lactis is an ovoid bacterium that forms filaments during planktonic and biofilm lifestyles by uncoupling cell division from cell elongation. In this work, we investigate the role of the leading peptidoglycan synthase PBP2b that is dedicated to cell elongation in ovococci. We show that the localization of a fluorescent derivative of PBP2b remains associated to the septal region and superimposed with structural changes of FtsZ during both vegetative growth and filamentation indicating that PBP2b remains intimately associated to the division machinery during the whole cell cycle. In addition, we show that PBP2b-negative cells of L. lactis are not only defective in peripheral growth; they are also affected in septum positioning. This septation defect does not simply result from the absence of the protein in the cell growth machinery since it is also observed when PBP2b-deficient cells are complemented by a catalytically inactive variant of PBP2b. Finally, we show that round cells resulting from β-lactam treatment are not altered in septation, suggesting that shape elongation as such is not a major determinant for selection of the division site. Altogether, we propose that the specific PBP2b transpeptidase activity at the septum plays an important role for tagging future division sites during L. lactis cell cycle.
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Affiliation(s)
- Blandine David
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Marie-Clémence Duchêne
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Gabrielle Laurie Haustenne
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Daniel Pérez-Núñez
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Xavier De Bolle
- Microorganisms Biology Research Unit (URBM), University of Namur (UNamur), Namur, Belgium
| | - Eric Guédon
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
- STLO, INRA, Agrocampus Ouest, Rennes, France
| | - Pascal Hols
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- * E-mail: (BH); (PH)
| | - Bernard Hallet
- Institut des Sciences de la Vie (ISV), Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- * E-mail: (BH); (PH)
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28
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The cell wall hydrolase Pmp23 is important for assembly and stability of the division ring in Streptococcus pneumoniae. Sci Rep 2018; 8:7591. [PMID: 29765094 PMCID: PMC5954120 DOI: 10.1038/s41598-018-25882-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 04/13/2018] [Indexed: 12/02/2022] Open
Abstract
Bacterial division is intimately linked to synthesis and remodeling of the peptidoglycan, a cage-like polymer that surrounds the bacterial cell, providing shape and mechanical resistance. The bacterial division machinery, which is scaffolded by the cytoskeleton protein FtsZ, includes proteins with enzymatic, structural or regulatory functions. These proteins establish a complex network of transient functional and/or physical interactions which preserve cell shape and cell integrity. Cell wall hydrolases required for peptidoglycan remodeling are major contributors to this mechanism. Consistent with this, their deletion or depletion often results in morphological and/or division defects. However, the exact function of most of them remains elusive. In this work, we show that the putative lysozyme activity of the cell wall hydrolase Pmp23 is important for proper morphology and cell division in the opportunistic human pathogen Streptococcus pneumoniae. Our data indicate that active Pmp23 is required for proper localization of the Z-ring and the FtsZ-positioning protein MapZ. In addition, Pmp23 localizes to the division site and interacts directly with the essential peptidoglycan synthase PBP2x. Altogether, our data reveal a new regulatory function for peptidoglycan hydrolases.
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29
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Engholm DH, Kilian M, Goodsell DS, Andersen ES, Kjærgaard RS. A visual review of the human pathogen Streptococcus pneumoniae. FEMS Microbiol Rev 2018; 41:854-879. [PMID: 29029129 DOI: 10.1093/femsre/fux037] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 09/04/2017] [Indexed: 11/12/2022] Open
Abstract
Being the principal causative agent of bacterial pneumonia, otitis media, meningitis and septicemia, the bacterium Streptococcus pneumoniae is a major global health problem. To highlight the molecular basis of this problem, we have portrayed essential biological processes of the pneumococcal life cycle in eight watercolor paintings. The paintings are done to a consistent nanometer scale based on currently available data from structural biology and proteomics. In this review article, the paintings are used to provide a visual review of protein synthesis, carbohydrate metabolism, cell wall synthesis, cell division, teichoic acid synthesis, virulence, transformation and pilus synthesis based on the available scientific literature within the field of pneumococcal biology. Visualization of the molecular details of these processes reveals several scientific questions about how molecular components of the pneumococcal cell are organized to allow biological function to take place. By the presentation of this visual review, we intend to stimulate scientific discussion, aid in the generation of scientific hypotheses and increase public awareness. A narrated video describing the biological processes in the context of a whole-cell illustration accompany this article.
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Affiliation(s)
- Ditte Høyer Engholm
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Mogens Kilian
- Department of Biomedicine, Aarhus University, 8000 Aarhus, Denmark
| | - David S Goodsell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.,Rutgers, the State University of New Jersey, NJ 08901, USA
| | - Ebbe Sloth Andersen
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark.,Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus, Denmark
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30
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Obergfell KP, Schaub RE, Priniski LL, Dillard JP, Seifert HS. The low-molecular-mass, penicillin-binding proteins DacB and DacC combine to modify peptidoglycan cross-linking and allow stable Type IV pilus expression in Neisseria gonorrhoeae. Mol Microbiol 2018; 109:135-149. [PMID: 29573486 DOI: 10.1111/mmi.13955] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2018] [Indexed: 11/28/2022]
Abstract
Neisseria gonorrhoeae is the causative agent of the sexually transmitted infection gonorrhea and is adapted to survive in humans, its only host. The N. gonorrhoeae cell wall is critical for maintaining envelope integrity, resisting immune cell killing and production of cytotoxic peptidoglycan (PG) fragments. Deletion of the N. gonorrhoeae strain FA1090 genes encoding two predicted low-molecular-mass, penicillin-binding proteins (LMM PBPs), DacB and DacC, substantially altered the PG cross-linking. Loss of the DacB peptidase resulted in global alterations to the PG composition, while loss of the DacC protein affected a much narrower subset of PG peptide components. A double ΔdacB/ΔdacC mutant resembled the ΔdacB single mutant, but had an even greater level of cross-linked PG. While single ΔdacB or ΔdacC mutants did not show any major phenotypes, the ΔdacB/ΔdacC mutant displayed an altered cellular morphology, decreased resistance to antibiotics and increased sensitivity to detergent-mediated death. Loss of the two proteins also drastically reduced the number of Type IV pili (Tfp), a critical virulence factor. The decreased piliation reduced transformation efficiency and correlated with increased growth rate. While these two LMM PBPs differentially alter the PG composition, their overlapping effects are essential to proper envelope function and expression of factors critical for pathogenesis.
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Affiliation(s)
- Kyle P Obergfell
- Department of Microbiology-Immunology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - Ryan E Schaub
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Lauren L Priniski
- Department of Microbiology-Immunology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
| | - Joseph P Dillard
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - H Steven Seifert
- Department of Microbiology-Immunology, Northwestern University's Feinberg School of Medicine, Chicago, IL, USA
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31
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Adediran SA, Sarkar KS, Pratt RF. Kinetic Evidence for a Second Ligand Binding Site on Streptococcus pneumoniae Penicillin-Binding Protein 2x. Biochemistry 2018; 57:1758-1766. [PMID: 29485264 DOI: 10.1021/acs.biochem.7b01209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High molecular mass penicillin-binding proteins (PBPs, DD-peptidases) of class B, such as Streptococcus pneumoniae PBP2x, catalyze the cross-linking of peptidoglycan in bacterial cell wall biosynthesis and are thus important antibiotic targets. Despite their importance in this regard, structure-function studies of ligands of these enzymes have been impeded by the absence of useful substrates. In vitro, these enzymes do not catalyze peptide hydrolysis or aminolysis, their in vivo reaction, but some, such as PBP2x, do catalyze these reactions of certain thioesters such as PhCH2CONHCH2COSCH(D-Me)CO2- (2). We have now prepared several peptidoglycan-mimetic thioesters that we expected to more closely resemble the natural substrates of these enzymes. To our surprise, however, these compounds, although indeed substrates of PBP2x, did not, unlike 2, appear to form an acyl-enzyme intermediate during hydrolysis, and their turnover was inhibited by certain peptides and N-acylamino acids much more weakly than that of 2. An inhibitor of this type, N-benzyloxycarbonyl-d-glutamic acid, also quenched the fluorescence of PBP2x that had been labeled at the DD-peptidase active site by 6-dansylamidopenicillanic acid. These results were interpreted in terms of a model where the peptidoglycan-mimetic thioesters preferentially bound to and hydrolyzed at a site other than the classical DD-peptidase active site. This second site is likely to represent part of an extended binding site that accommodates a peptidoglycan substrate or regulator in vivo. Such a site may be a target for future inhibitor/antibiotic design.
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Affiliation(s)
- S A Adediran
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
| | - Kumar Subarno Sarkar
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
| | - R F Pratt
- Department of Chemistry , Wesleyan University , Lawn Avenue , Middletown , Connecticut 06459 , United States
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32
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van der Linden M, Rutschmann J, Maurer P, Hakenbeck R. PBP2a in β-Lactam-Resistant Laboratory Mutants and Clinical Isolates: Disruption Versus Reduced Penicillin Affinity. Microb Drug Resist 2017; 24:718-731. [PMID: 29195053 DOI: 10.1089/mdr.2017.0302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Alterations in PBP2a have been recognized in cefotaxime-resistant laboratory mutants and β-lactam-resistant clinical isolates of Streptococcus pneumoniae. DNA sequencing revealed fundamental differences between these two settings. Internal stop codons in pbp2a occurred in all three laboratory mutants analyzed, caused by a mutation in pbp2a of mutant C604, and tandem duplications within pbp2a resulting in premature stop codons in another two mutants C403 and C406. In contrast, mosaic PBP2a genes were observed in several penicillin-resistant clinical isolates from South Africa, the Czech Republic, Hungary, and in the clone Poland23F-16, with sequence blocks diverging from sensitive strains by over 4%. Most of these pbp2a variants except pbp2a from the South African strain contained sequences related to pbp2a of Streptococcus mitis B6, confirming that this species serves as reservoir for penicillin-resistance determinants.
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Affiliation(s)
- Mark van der Linden
- 1 Department of Medical Microbiology, German National Reference Center for Streptococci , Aachen, Germany
| | | | - Patrick Maurer
- 3 School of Engineering, University of Applied Sciences , Saarbrücken, Germany
| | - Regine Hakenbeck
- 4 Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
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33
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Zheng JJ, Perez AJ, Tsui HCT, Massidda O, Winkler ME. Absence of the KhpA and KhpB (JAG/EloR) RNA-binding proteins suppresses the requirement for PBP2b by overproduction of FtsA in Streptococcus pneumoniae D39. Mol Microbiol 2017; 106:793-814. [PMID: 28941257 DOI: 10.1111/mmi.13847] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2017] [Indexed: 12/11/2022]
Abstract
Suppressor mutations were isolated that obviate the requirement for essential PBP2b in peripheral elongation of peptidoglycan from the midcells of dividing Streptococcus pneumoniae D39 background cells. One suppressor was in a gene encoding a single KH-domain protein (KhpA). ΔkhpA suppresses deletions in most, but not all (mltG), genes involved in peripheral PG synthesis and in the gpsB regulatory gene. ΔkhpA mutations reduce growth rate, decrease cell size, minimally affect shape and induce expression of the WalRK cell-wall stress regulon. Reciprocal co-immunoprecipitations show that KhpA forms a complex in cells with another KH-domain protein (KhpB/JAG/EloR). ΔkhpA and ΔkhpB mutants phenocopy each other exactly, consistent with a direct interaction. RNA-immunoprecipitation showed that KhpA/KhpB bind an overlapping set of RNAs in cells. Phosphorylation of KhpB reported previously does not affect KhpB function in the D39 progenitor background. A chromosome duplication implicated FtsA overproduction in Δpbp2b suppression. We show that cellular FtsA concentration is negatively regulated by KhpA/B at the post-transcriptional level and that FtsA overproduction is necessary and sufficient for suppression of Δpbp2b. However, increased FtsA only partially accounts for the phenotypes of ΔkhpA mutants. Together, these results suggest that multimeric KhpA/B may function as a pleiotropic RNA chaperone controlling pneumococcal cell division.
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Affiliation(s)
- Jiaqi J Zheng
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Amilcar J Perez
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Ho-Ching Tiffany Tsui
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
| | - Orietta Massidda
- Dipartimento di Scienze Chirurgiche, Università di Cagliari, 09100 Cagliari, Italy
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington (IUB), Bloomington, IN 47405, USA
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34
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Stamsås GA, Straume D, Ruud Winther A, Kjos M, Frantzen CA, Håvarstein LS. Identification of EloR (Spr1851) as a regulator of cell elongation in Streptococcus pneumoniae. Mol Microbiol 2017; 105:954-967. [PMID: 28710862 DOI: 10.1111/mmi.13748] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/10/2017] [Accepted: 07/11/2017] [Indexed: 01/28/2023]
Abstract
In a screen for mutations suppressing the lethal loss of PBP2b in Streptococcus pneumoniae we identified Spr1851 (named EloR), a cytoplasmic protein of unknown function whose inactivation removed the requirement for PBP2b as well as RodA. It follows from this that EloR and the two elongasome proteins must be part of the same functional network. This network also includes StkP, as this serine/threonine kinase phosphorylates EloR on threonine 89 (T89). We found that ΔeloR cells, and cells expressing the phosphoablative form of EloR (EloRT89A ), are significantly shorter than wild-type cells. Furthermore, the phosphomimetic form of EloR (EloRT89E ) is not tolerated unless the cell in addition acquires a truncated MreC or non-functional RodZ protein. By itself, truncation of MreC as well as inactivation of RodZ gives rise to less elongated cells, demonstrating that the stress exerted by the phosphomimetic form of EloR is relieved by suppressor mutations that reduce or abolish the activity of the elongasome. Of note, it was also found that loss of elongasome activity caused by truncation of MreC elicits increased StkP-mediated phosphorylation of EloR. Together, the results support a model in which phosphorylation of EloR stimulates cell elongation, while dephosphorylation has an inhibitory effect.
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Affiliation(s)
- Gro Anita Stamsås
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
| | - Daniel Straume
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
| | - Anja Ruud Winther
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
| | - Cyril Alexander Frantzen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
| | - Leiv Sigve Håvarstein
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, NO-1432, Ås, Norway
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35
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Itzek A, Chen Z, Merritt J, Kreth J. Effect of salivary agglutination on oral streptococcal clearance by human polymorphonuclear neutrophil granulocytes. Mol Oral Microbiol 2017; 32:197-210. [PMID: 27194631 PMCID: PMC5116291 DOI: 10.1111/omi.12164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2016] [Indexed: 12/20/2022]
Abstract
Salivary agglutination is an important host defense mechanism to aggregate oral commensal bacteria as well as invading pathogens. Saliva flow and subsequent swallowing more easily clear aggregated bacteria compared with single cells. Phagocytic clearance of bacteria through polymorphonuclear neutrophil granulocytes also seems to increase to a certain extent with the size of bacterial aggregates. To determine a connection between salivary agglutination and the host innate immune response by phagocytosis, an in vitro agglutination assay was developed reproducing the average size of salivary bacterial aggregates. Using the oral commensal Streptococcus gordonii as a model organism, the effect of salivary agglutination on phagocytic clearance through polymorphonuclear neutrophil granulocytes was investigated. Here we describe how salivary aggregates of S. gordonii are readily cleared through phagocytosis, whereas single bacterial cells showed a significant delay in being phagocytosed and killed. Furthermore, before phagocytosis the polymorphonuclear neutrophil granulocytes were able to induce a specific de-aggregation, which was dependent on serine protease activity. The data presented suggest that salivary agglutination of bacterial cells leads to an ideal size for recognition by polymorphonuclear neutrophil granulocytes. As a first line of defense, these phagocytic cells are able to recognize the aggregates and de-aggregate them via serine proteases to a more manageable size for efficient phagocytosis and subsequent killing in the phagolysosome. This observed mechanism not only prevents the rapid spreading of oral bacterial cells while entering the bloodstream but would also avoid degranulation of involved polymorphonuclear neutrophil granulocytes, so preventing collateral damage to nearby tissue.
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Affiliation(s)
- Andreas Itzek
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Zhiyun Chen
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Justin Merritt
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
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36
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Arrigucci R, Pozzi G. Identification of the chain-dispersing peptidoglycan hydrolase LytB of Streptococcus gordonii. PLoS One 2017; 12:e0176117. [PMID: 28414782 PMCID: PMC5393624 DOI: 10.1371/journal.pone.0176117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 04/05/2017] [Indexed: 12/05/2022] Open
Abstract
Bacterial cell division ends with the separation of the daughter cells, a process that requires peptidoglycan hydrolases (PGHs). Bacteria lacking cell separating PGHs are impaired in cell separation with the formation of long chains or clusters. We identified a gene in Streptococcus gordonii encoding for a putative glucosaminidase (lytB). The lytB isogenic mutant grew in long bacterial chains and resulted in impaired biofilm formation. Purified recombinant LytB showed a murolytic activity on Micrococcus lysodeikticus cell suspension and was able to disperse the long chains of the mutant, restoring the wild type diplococci/short chain phenotype. LytB protein was localized only in culture supernatant cell fraction of S. gordonii, and co-cultures of wild type and lytB mutant showed a significant reduction of bacterial chain length, indicating that LytB is a secreted enzyme. Our results demonstrate that LytB is a secreted peptidoglycan hydrolase required for S. gordonii cell separation.
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Affiliation(s)
- Riccardo Arrigucci
- Public Health Research Institute, Rutgers, The State University of New Jersey, Newark, NJ, United States of America
- * E-mail:
| | - Gianni Pozzi
- LAMMB, Department of Medical Biotechnologies, University of Siena, Siena, Italy
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37
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Roles of the Essential Protein FtsA in Cell Growth and Division in Streptococcus pneumoniae. J Bacteriol 2017; 199:JB.00608-16. [PMID: 27872183 DOI: 10.1128/jb.00608-16] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 11/16/2016] [Indexed: 11/20/2022] Open
Abstract
Streptococcus pneumoniae is an ovoid-shaped Gram-positive bacterium that grows by carrying out peripheral and septal peptidoglycan (PG) synthesis, analogous to model bacilli, such as Escherichia coli and Bacillus subtilis In the model bacilli, FtsZ and FtsA proteins assemble into a ring at midcell and are dedicated to septal PG synthesis but not peripheral PG synthesis; hence, inactivation of FtsZ or FtsA results in long filamentous cells unable to divide. Here, we demonstrate that FtsA and FtsZ colocalize at midcell in S. pneumoniae and that partial depletion of FtsA perturbs septum synthesis, resulting in elongated cells with multiple FtsZ rings that fail to complete septation. Unexpectedly, complete depletion of FtsA resulted in the delocalization of FtsZ rings and ultimately cell ballooning and lysis. In contrast, depletion or deletion of gpsB and sepF, which in B. subtilis are synthetically lethal with ftsA, resulted in enlarged and elongated cells with multiple FtsZ rings, with deletion of sepF mimicking partial depletion of FtsA. Notably, cell ballooning was not observed, consistent with later recruitment of these proteins to midcell after Z-ring assembly. The overproduction of FtsA stimulates septation and suppresses the cell division defects caused by the deletion of sepF and gpsB under some conditions, supporting the notion that FtsA shares overlapping functions with GpsB and SepF at later steps in the division process. Our results indicate that, in S. pneumoniae, both GpsB and SepF are involved in septal PG synthesis, whereas FtsA and FtsZ coordinate both peripheral and septal PG synthesis and are codependent for localization at midcell.IMPORTANCEStreptococcus pneumoniae (pneumococcus) is a clinically important human pathogen for which more therapies against unexploited essential targets, like cell growth and division proteins, are needed. Pneumococcus is an ovoid-shaped Gram-positive bacterium with cell growth and division properties that have important distinctions from those of rod-shaped bacteria. Gaining insights into these processes can thus provide valuable information to develop novel antimicrobials. Whereas rods use distinctly localized protein machines at different cellular locations to synthesize peripheral and septal peptidoglycans, we present evidence that S. pneumoniae organizes these two machines at a single location in the middle of dividing cells. Here, we focus on the properties of the actin-like protein FtsA as an essential orchestrator of peripheral and septal growth in this bacterium.
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Schumacher MA. Bacterial Nucleoid Occlusion: Multiple Mechanisms for Preventing Chromosome Bisection During Cell Division. Subcell Biochem 2017; 84:267-298. [PMID: 28500529 DOI: 10.1007/978-3-319-53047-5_9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In most bacteria cell division is driven by the prokaryotic tubulin homolog, FtsZ, which forms the cytokinetic Z ring. Cell survival demands both the spatial and temporal accuracy of this process to ensure that equal progeny are produced with intact genomes. While mechanisms preventing septum formation at the cell poles have been known for decades, the means by which the bacterial nucleoid is spared from bisection during cell division, called nucleoid exclusion (NO), have only recently been deduced. The NO theory was originally posited decades ago based on the key observation that the cell division machinery appeared to be inhibited from forming near the bacterial nucleoid. However, what might drive the NO process was unclear. Within the last 10 years specific proteins have been identified as important mediators of NO. Arguably the best studied NO mechanisms are those employed by the Escherichia coli SlmA and Bacillus subtilis Noc proteins. Both proteins bind specific DNA sequences within selected chromosomal regions to act as timing devices. However, Noc and SlmA contain completely different structural folds and utilize distinct NO mechanisms. Recent studies have identified additional processes and factors that participate in preventing nucleoid septation during cell division. These combined data show multiple levels of redundancy as well as a striking diversity of mechanisms have evolved to protect cells against catastrophic bisection of the nucleoid. Here we discuss these recent findings with particular emphasis on what is known about the molecular underpinnings of specific NO machinery and processes.
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Affiliation(s)
- Maria A Schumacher
- Department of Biochemistry, Duke University School of Medicine, 243 Nanaline H. Duke, Durham, NC, 27710, USA.
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Veiga H, G Pinho M. Staphylococcus aureus requires at least one FtsK/SpoIIIE protein for correct chromosome segregation. Mol Microbiol 2016; 103:504-517. [PMID: 27886417 DOI: 10.1111/mmi.13572] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2016] [Indexed: 11/30/2022]
Abstract
Faithful coordination between bacterial cell division and chromosome segregation in rod-shaped bacteria, such as Escherichia coli and Bacillus subtilis, is dependent on the DNA translocase activity of FtsK/SpoIIIE proteins, which move DNA away from the division site before cytokinesis is completed. However, the role of these proteins in chromosome partitioning has not been well studied in spherical bacteria. Here, it was shown that the two Staphylococcus aureus FtsK/SpoIIIE homologues, SpoIIIE and FtsK, operate in independent pathways to ensure correct chromosome management during cell division. SpoIIIE forms foci at the centre of the closing septum in at least 50% of the cells that are close to complete septum synthesis. FtsK is a multifunctional septal protein with a C-terminal DNA translocase domain that is not required for correct chromosome management in the presence of SpoIIIE. However, lack of both SpoIIIE and FtsK causes severe nucleoid segregation and morphological defects, showing that the two proteins have partially redundant roles in S. aureus.
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Affiliation(s)
- Helena Veiga
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Mariana G Pinho
- Laboratory of Bacterial Cell Biology, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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Straume D, Stamsås GA, Berg KH, Salehian Z, Håvarstein LS. Identification of pneumococcal proteins that are functionally linked to penicillin-binding protein 2b (PBP2b). Mol Microbiol 2016; 103:99-116. [DOI: 10.1111/mmi.13543] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Straume
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Sciences; Ås NO-1432 Norway
| | - Gro Anita Stamsås
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Sciences; Ås NO-1432 Norway
| | - Kari Helene Berg
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Sciences; Ås NO-1432 Norway
| | - Zhian Salehian
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Sciences; Ås NO-1432 Norway
| | - Leiv Sigve Håvarstein
- Department of Chemistry, Biotechnology and Food Science; Norwegian University of Life Sciences; Ås NO-1432 Norway
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Ulrych A, Holečková N, Goldová J, Doubravová L, Benada O, Kofroňová O, Halada P, Branny P. Characterization of pneumococcal Ser/Thr protein phosphatase phpP mutant and identification of a novel PhpP substrate, putative RNA binding protein Jag. BMC Microbiol 2016; 16:247. [PMID: 27776484 PMCID: PMC5078927 DOI: 10.1186/s12866-016-0865-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 10/14/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Reversible protein phosphorylation catalyzed by protein kinases and phosphatases is the primary mechanism for signal transduction in all living organisms. Streptococcus pneumoniae encodes a single Ser/Thr protein kinase, StkP, which plays a role in virulence, stress resistance and the regulation of cell wall synthesis and cell division. However, the role of its cognate phosphatase, PhpP, is not well defined. RESULTS Here, we report the successful construction of a ΔphpP mutant in the unencapsulated S. pneumoniae Rx1 strain and the characterization of its phenotype. We demonstrate that PhpP negatively controls the level of protein phosphorylation in S. pneumoniae both by direct dephosphorylation of target proteins and by dephosphorylation of its cognate kinase, StkP. Catalytic inactivation or absence of PhpP resulted in the hyperphosphorylation of StkP substrates and specific phenotypic changes, including sensitivity to environmental stresses and competence deficiency. The morphology of the ΔphpP cells resembled the StkP overexpression phenotype and conversely, overexpression of PhpP resulted in cell elongation mimicking the stkP null phenotype. Proteomic analysis of the phpP knock-out strain permitted identification of a novel StkP/PhpP substrate, Spr1851, a putative RNA-binding protein homologous to Jag. Here, we show that pneumococcal Jag is phosphorylated on Thr89. Inactivation of jag confers a phenotype similar to the phpP mutant strain. CONCLUSIONS Our results suggest that PhpP and StkP cooperatively regulate cell division of S. pneumoniae and phosphorylate putative RNA binding protein Jag.
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Affiliation(s)
- Aleš Ulrych
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Nela Holečková
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Jana Goldová
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Linda Doubravová
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic.
| | - Oldřich Benada
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Olga Kofroňová
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Petr Halada
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Pavel Branny
- Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic.
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Grangeasse C. Rewiring the Pneumococcal Cell Cycle with Serine/Threonine- and Tyrosine-kinases. Trends Microbiol 2016; 24:713-724. [DOI: 10.1016/j.tim.2016.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 03/23/2016] [Accepted: 04/07/2016] [Indexed: 12/14/2022]
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Kylväjä R, Ojalehto T, Kainulainen V, Virkola R, Westerlund-Wikström B. Penicillin binding protein 3 of Staphylococcus aureus NCTC 8325-4 binds and activates human plasminogen. BMC Res Notes 2016; 9:389. [PMID: 27488131 PMCID: PMC4972960 DOI: 10.1186/s13104-016-2190-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/28/2016] [Indexed: 11/25/2022] Open
Abstract
Background Staphylococcus aureus is a versatile pathogen expressing a number of virulence-associated adhesive molecules. In a previous study, we generated in a secretion-competent Escherichia coli strain a library of random FLAG-tag positive (FTP) polypeptides of S. aureus. To identify adhesive proteins and gain additional knowledge on putative virulence factors of S. aureus, we here screened the FTP library against human serum proteins. Findings Staphylococcus aureus NCTC 8325-4, origin of the FTP library, adhered to immobilized plasminogen in vitro. In an enzyme-linked immunoassay a C-terminal part of penicillin binding protein 3 (PBP3), included in the FTP library, bound to immobilized plasminogen. We expressed and purified full-length PBP3 and its C-terminal fragments as recombinant proteins. In a time-resolved fluorometry—based assay the PBP3 polypeptides bound to immobilized plasminogen. The polypeptides enhanced formation of plasmin from plasminogen as analyzed by cleavage of a chromogenic plasmin substrate. Conclusions The present findings, although preliminary, demonstrate reliably that S. aureus NCTC 8325-4 adheres to immobilized plasminogen in vitro and that the adhesion may be mediated by a C-terminal fragment of the PBP3 protein. The full length PBP3 and the penicillin binding C-terminal domain of PBP3 expressed as recombinant proteins bound plasminogen and activated plasminogen to plasmin. These phenomena were inhibited by the lysine analogue ε-aminocaproic acid suggesting that the binding is mediated by lysine residues. A detailed molecular description of surface molecules enhancing the virulence of S. aureus will aid in understanding of its pathogenicity and help in design of antibacterial drugs in the future. Electronic supplementary material The online version of this article (doi:10.1186/s13104-016-2190-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Riikka Kylväjä
- General Microbiology, Department of Biosciences, University of Helsinki, P.O.Box 56, FI-00014, University of Helsinki, Helsinki, Finland.,Thermo Fisher Scientific, Ratastie 2, 01620, Vantaa, Finland
| | - Tuomas Ojalehto
- General Microbiology, Department of Biosciences, University of Helsinki, P.O.Box 56, FI-00014, University of Helsinki, Helsinki, Finland.,Orion Diagnostica, Koivu-Mankkaan tie 6, 02200, Espoo, Finland
| | - Veera Kainulainen
- General Microbiology, Department of Biosciences, University of Helsinki, P.O.Box 56, FI-00014, University of Helsinki, Helsinki, Finland.,Pharmacology, Faculty of Medicine, University of Helsinki, P.O.Box 63, FI-00014, University of Helsinki, Helsinki, Finland
| | - Ritva Virkola
- General Microbiology, Department of Biosciences, University of Helsinki, P.O.Box 56, FI-00014, University of Helsinki, Helsinki, Finland
| | - Benita Westerlund-Wikström
- General Microbiology, Department of Biosciences, University of Helsinki, P.O.Box 56, FI-00014, University of Helsinki, Helsinki, Finland.
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Peters K, Pipo J, Schweizer I, Hakenbeck R, Denapaite D. Promoter Identification and Transcription Analysis of Penicillin-Binding Protein Genes in Streptococcus pneumoniae R6. Microb Drug Resist 2016; 22:487-98. [PMID: 27409661 PMCID: PMC5036317 DOI: 10.1089/mdr.2016.0084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Penicillin-binding proteins (PBPs) are membrane-associated enzymes, which are involved in the last two steps of peptidoglycan biosynthesis, and some of them are key players in cell division. Furthermore, they are targets of β-lactams, the most widely used antibiotics. Nevertheless, very little is known about the expression and regulation of PBP genes. Using transcriptional mapping, we now determined the promoter regions of PBP genes from the laboratory strain Streptococcus pneumoniae R6 and examined the expression profile of these six promoters. The extended −10 region is highly conserved and complies with a σA-type promoter consensus sequence. In contrast, the −35 region is poorly conserved, indicating the possibility for differential PBP regulation. All PBP promoters were constitutively expressed and highly active during the exponential and early stationary growth phase. However, the individual expression of PBP promoters varied approximately fourfold, with pbp1a being the highest and pbp3 the lowest. Furthermore, the deletion of one nucleotide in the spacer region of the PBP3 promoter reduced pbp3 expression ∼10-fold. The addition of cefotaxime above the minimal inhibitory concentration (MIC) did not affect PBP expression in the penicillin-sensitive R6 strain. No evidence for regulation of S. pneumoniae PBP genes was obtained.
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Affiliation(s)
- Katharina Peters
- Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
| | - Julia Pipo
- Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
| | - Inga Schweizer
- Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
| | - Regine Hakenbeck
- Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
| | - Dalia Denapaite
- Department of Microbiology, University of Kaiserslautern , Kaiserslautern, Germany
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Structure-function analysis of the extracellular domain of the pneumococcal cell division site positioning protein MapZ. Nat Commun 2016; 7:12071. [PMID: 27346279 PMCID: PMC4931243 DOI: 10.1038/ncomms12071] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 05/25/2016] [Indexed: 11/09/2022] Open
Abstract
Accurate placement of the bacterial division site is a prerequisite for the generation of two viable and identical daughter cells. In Streptococcus pneumoniae, the positive regulatory mechanism involving the membrane protein MapZ positions precisely the conserved cell division protein FtsZ at the cell centre. Here we characterize the structure of the extracellular domain of MapZ and show that it displays a bi-modular structure composed of two subdomains separated by a flexible serine-rich linker. We further demonstrate in vivo that the N-terminal subdomain serves as a pedestal for the C-terminal subdomain, which determines the ability of MapZ to mark the division site. The C-terminal subdomain displays a patch of conserved amino acids and we show that this patch defines a structural motif crucial for MapZ function. Altogether, this structure–function analysis of MapZ provides the first molecular characterization of a positive regulatory process of bacterial cell division. Placement of the bacterial division site is crucial for the creation of identical daughter cells. Here, the authors solve the structure of the MapZ protein, which helps to position the cell division protein FtsZ at the cell centre, and further analyse the function of the protein in vivo.
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Tsui HCT, Zheng JJ, Magallon AN, Ryan JD, Yunck R, Rued BE, Bernhardt TG, Winkler ME. Suppression of a deletion mutation in the gene encoding essential PBP2b reveals a new lytic transglycosylase involved in peripheral peptidoglycan synthesis in Streptococcus pneumoniae D39. Mol Microbiol 2016; 100:1039-65. [PMID: 26933838 DOI: 10.1111/mmi.13366] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In ellipsoid-shaped ovococcus bacteria, such as the pathogen Streptococcus pneumoniae (pneumococcus), side-wall (peripheral) peptidoglycan (PG) synthesis emanates from midcells and is catalyzed by the essential class B penicillin-binding protein PBP2b transpeptidase (TP). We report that mutations that inactivate the pneumococcal YceG-domain protein, Spd_1346 (renamed MltG), remove the requirement for PBP2b. ΔmltG mutants in unencapsulated strains accumulate inactivation mutations of class A PBP1a, which possesses TP and transglycosylase (TG) activities. The 'synthetic viable' genetic relationship between Δpbp1a and ΔmltG mutations extends to essential ΔmreCD and ΔrodZ mutations that misregulate peripheral PG synthesis. Remarkably, the single MltG(Y488D) change suppresses the requirement for PBP2b, MreCD, RodZ and RodA. Structural modeling and comparisons, catalytic-site changes and an interspecies chimera indicate that pneumococcal MltG is the functional homologue of the recently reported MltG endo-lytic transglycosylase of Escherichia coli. Depletion of pneumococcal MltG or mltG(Y488D) increases sphericity of cells, and MltG localizes with peripheral PG synthesis proteins during division. Finally, growth of Δpbp1a ΔmltG or mltG(Y488D) mutants depends on induction of expression of the WalRK TCS regulon of PG hydrolases. These results fit a model in which MltG releases anchored PG glycan strands synthesized by PBP1a for crosslinking by a PBP2b:RodA complex in peripheral PG synthesis.
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Affiliation(s)
| | - Jiaqi J Zheng
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Ariel N Magallon
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - John D Ryan
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Rachel Yunck
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, 02115, USA
| | - Britta E Rued
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Thomas G Bernhardt
- Department of Microbiology and Immunology, Harvard Medical School, Boston, MA, 02115, USA
| | - Malcolm E Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, IN, 47405, USA
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Glycosyltransferases and Transpeptidases/Penicillin-Binding Proteins: Valuable Targets for New Antibacterials. Antibiotics (Basel) 2016; 5:antibiotics5010012. [PMID: 27025527 PMCID: PMC4810414 DOI: 10.3390/antibiotics5010012] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/27/2016] [Accepted: 02/03/2016] [Indexed: 12/29/2022] Open
Abstract
Peptidoglycan (PG) is an essential macromolecular sacculus surrounding most bacteria. It is assembled by the glycosyltransferase (GT) and transpeptidase (TP) activities of multimodular penicillin-binding proteins (PBPs) within multiprotein complex machineries. Both activities are essential for the synthesis of a functional stress-bearing PG shell. Although good progress has been made in terms of the functional and structural understanding of GT, finding a clinically useful antibiotic against them has been challenging until now. In contrast, the TP/PBP module has been successfully targeted by β-lactam derivatives, but the extensive use of these antibiotics has selected resistant bacterial strains that employ a wide variety of mechanisms to escape the lethal action of these antibiotics. In addition to traditional β-lactams, other classes of molecules (non-β-lactams) that inhibit PBPs are now emerging, opening new perspectives for tackling the resistance problem while taking advantage of these valuable targets, for which a wealth of structural and functional knowledge has been accumulated. The overall evidence shows that PBPs are part of multiprotein machineries whose activities are modulated by cofactors. Perturbation of these systems could lead to lethal effects. Developing screening strategies to take advantage of these mechanisms could lead to new inhibitors of PG assembly. In this paper, we present a general background on the GTs and TPs/PBPs, a survey of recent issues of bacterial resistance and a review of recent works describing new inhibitors of these enzymes.
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Abachi S, Lee S, Rupasinghe HPV. Molecular Mechanisms of Inhibition of Streptococcus Species by Phytochemicals. Molecules 2016; 21:E215. [PMID: 26901172 PMCID: PMC6273676 DOI: 10.3390/molecules21020215] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/04/2016] [Accepted: 02/06/2016] [Indexed: 12/11/2022] Open
Abstract
This review paper summarizes the antibacterial effects of phytochemicals of various medicinal plants against pathogenic and cariogenic streptococcal species. The information suggests that these phytochemicals have potential as alternatives to the classical antibiotics currently used for the treatment of streptococcal infections. The phytochemicals demonstrate direct bactericidal or bacteriostatic effects, such as: (i) prevention of bacterial adherence to mucosal surfaces of the pharynx, skin, and teeth surface; (ii) inhibition of glycolytic enzymes and pH drop; (iii) reduction of biofilm and plaque formation; and (iv) cell surface hydrophobicity. Collectively, findings from numerous studies suggest that phytochemicals could be used as drugs for elimination of infections with minimal side effects.
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Affiliation(s)
- Soheila Abachi
- Faculty of Agriculture, Dalhousie University, Truro, NS PO Box 550, Canada.
| | - Song Lee
- Faculty of Dentistry, Dalhousie University, Halifax, NS PO Box 15000, Canada.
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Staying in Shape: the Impact of Cell Shape on Bacterial Survival in Diverse Environments. Microbiol Mol Biol Rev 2016; 80:187-203. [PMID: 26864431 DOI: 10.1128/mmbr.00031-15] [Citation(s) in RCA: 159] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria display an abundance of cellular forms and can change shape during their life cycle. Many plausible models regarding the functional significance of cell morphology have emerged. A greater understanding of the genetic programs underpinning morphological variation in diverse bacterial groups, combined with assays of bacteria under conditions that mimic their varied natural environments, from flowing freshwater streams to diverse human body sites, provides new opportunities to probe the functional significance of cell shape. Here we explore shape diversity among bacteria, at the levels of cell geometry, size, and surface appendages (both placement and number), as it relates to survival in diverse environments. Cell shape in most bacteria is determined by the cell wall. A major challenge in this field has been deconvoluting the effects of differences in the chemical properties of the cell wall and the resulting cell shape perturbations on observed fitness changes. Still, such studies have begun to reveal the selective pressures that drive the diverse forms (or cell wall compositions) observed in mammalian pathogens and bacteria more generally, including efficient adherence to biotic and abiotic surfaces, survival under low-nutrient or stressful conditions, evasion of mammalian complement deposition, efficient dispersal through mucous barriers and tissues, and efficient nutrient acquisition.
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Spatial Organization of Cell Wall-Anchored Proteins at the Surface of Gram-Positive Bacteria. Curr Top Microbiol Immunol 2016; 404:177-201. [DOI: 10.1007/82_2016_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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