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Komikawa T, Okochi M, Tanaka M. Exploration and analytical techniques for membrane curvature-sensing proteins in bacteria. J Bacteriol 2025; 207:e0048224. [PMID: 40135904 PMCID: PMC12004969 DOI: 10.1128/jb.00482-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2025] Open
Abstract
The mechanism by which cells regulate protein localization is an important topic in the field of bacterial biology. In certain instances, the morphology of the biological membrane has been demonstrated to function as a spatial cue for the subcellular localization of proteins. These proteins are capable of sensing membrane curvature and are involved in a number of physiological functions such as cytokinesis and the formation of membrane-bound organelles. This review presents recent advances in the in vitro evaluation of curvature-sensing properties using artificially controlled membranes and purified proteins, as well as microscopic live cell assays. However, these evaluation methodologies often require sophisticated experiments, and the number of identified curvature sensors remains limited. Thus, we present a comprehensive exploration of recently reported curvature-sensing proteins. Subsequently, we summarize the known curvature-sensing proteins in bacteria, in conjunction with the analytical methodologies employed in this field. Finally, future prospects and further requirements in the study of curvature-sensing proteins are discussed.
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Affiliation(s)
- Takumi Komikawa
- School of Materials and Chemical Technology, Institute of Science Tokyo, Yokohama, Kanagawa, Japan
| | - Mina Okochi
- School of Materials and Chemical Technology, Institute of Science Tokyo, Meguro, Tokyo, Japan
| | - Masayoshi Tanaka
- School of Materials and Chemical Technology, Institute of Science Tokyo, Yokohama, Kanagawa, Japan
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2
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Pumirat P, Santajit S, Tunyong W, Kong-Ngoen T, Tandhavanant S, Lohitthai S, Rungruengkitkun A, Chantratita N, Ampawong S, Reamtong O, Indrawattana N. Impact of AbaI mutation on virulence, biofilm development, and antibiotic susceptibility in Acinetobacter baumannii. Sci Rep 2024; 14:21521. [PMID: 39277662 PMCID: PMC11401864 DOI: 10.1038/s41598-024-72740-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 09/10/2024] [Indexed: 09/17/2024] Open
Abstract
The quorum sensing (QS) system mediated by the abaI gene in Acinetobacter baumannii is crucial for various physiological and pathogenic processes. In this study, we constructed a stable markerless abaI knockout mutant (ΔabaI) strain using a pEXKm5-based allele replacement method to investigate the impact of abaI on A. baumannii. Proteomic analysis revealed significant alterations in protein expression between the wild type (WT) and ΔabaI mutant strains, particularly in proteins associated with membrane structure, antibiotic resistance, and virulence. Notably, the downregulation of key outer membrane proteins such as SurA, OmpA, OmpW, and BamA suggests potential vulnerabilities in outer membrane integrity, which correlate with structural abnormalities in the ΔabaI mutant strain, including irregular cell shapes and compromised membrane integrity, observed by scanning and transmission electron microscopy. Furthermore, diminished expression of regulatory proteins such as OmpR and GacA-GacS highlights the broader regulatory networks affected by abaI deletion. Functional assays revealed impaired biofilm formation and surface-associated motility in the mutant strain, indicative of altered colonization capabilities. Interestingly, the mutant showed a complex antibiotic susceptibility profile. While it demonstrated increased susceptibility to membrane-targeting antibiotics, its response to beta-lactams was more nuanced. Despite increased expression of metallo-beta-lactamase (MBL) superfamily proteins and DcaP-like protein, the mutant unexpectedly showed lower MICs for carbapenems (imipenem and meropenem) compared to the wild-type strain. This suggests that abaI deletion affects antibiotic susceptibility through multiple, potentially competing mechanisms. Further investigation is needed to fully elucidate the interplay between quorum sensing, antibiotic resistance genes, and overall antibiotic susceptibility in A. baumannii. Our findings underscore the multifaceted role of the abaI gene in modulating various cellular processes and highlight its significance in A. baumannii physiology, pathogenesis, and antibiotic resistance. Targeting the abaI QS system may offer novel therapeutic strategies for this clinically significant pathogen.
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Affiliation(s)
- Pornpan Pumirat
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
| | - Sirijan Santajit
- Department of Medical Technology, School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, Thailand
| | - Witawat Tunyong
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
| | - Thida Kong-Ngoen
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
| | - Sarunporn Tandhavanant
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
- Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Sanisa Lohitthai
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
| | | | - Narisara Chantratita
- Department of Microbiology and Immunology, Mahidol University, Bangkok, Thailand
| | - Sumate Ampawong
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Onrapak Reamtong
- Department of Tropical Molecular Biology and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nitaya Indrawattana
- Biomedical Research Incubator Unit, Department of Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
- Department of Research, Siriraj Center of Research Excellence in Allergy and Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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3
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Dersch S, Graumann PL. Adaptation of Bacillus subtilis MreB Filaments to Osmotic Stress Depends on Influx of Potassium Ions. Microorganisms 2024; 12:1309. [PMID: 39065078 PMCID: PMC11279060 DOI: 10.3390/microorganisms12071309] [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: 05/02/2024] [Revised: 06/13/2024] [Accepted: 06/20/2024] [Indexed: 07/28/2024] Open
Abstract
The circumferential motion of MreB filaments plays a key role in cell shape maintenance in many bacteria. It has recently been shown that filament formation of MreB filaments in Bacillus subtilis is influenced by stress conditions. In response to osmotic upshift, MreB molecules were released from filaments, as seen by an increase in freely diffusive molecules, and the peptidoglycan synthesis pattern became less organized, concomitant with slowed-down cell extension. In this study, biotic and abiotic factors were analysed with respect to a possible function in the adaptation of MreB filaments to stress conditions. We show that parallel to MreB, its interactor RodZ becomes more diffusive following osmotic stress, but the remodeling of MreB filaments is not affected by a lack of RodZ. Conversely, mutant strains that prevent efficient potassium influx into cells following osmotic shock show a failure to disassemble MreB filaments, accompanied by less perturbed cell wall extension than is observed in wild type cells. Because potassium ions are known to negatively affect MreB polymerization in vitro, our data indicate that polymer disassembly is directly mediated by the physical consequences of the osmotic stress response. The lack of an early potassium influx response strongly decreases cell survival following stress application, suggesting that the disassembly of MreB filaments may ensure slowed-down cell wall extension to allow for efficient adaptation to new osmotic conditions.
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Affiliation(s)
| | - Peter L. Graumann
- Centre for Synthetic Microbiology (SYNMIKRO), Fachbereich Chemie, Philipps-Universität Marburg, 35032 Marburg, Germany;
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4
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Awal RP, Müller FD, Pfeiffer D, Monteil CL, Perrière G, Lefèvre CT, Schüler D. Experimental analysis of diverse actin-like proteins from various magnetotactic bacteria by functional expression in Magnetospirillum gryphiswaldense. mBio 2023; 14:e0164923. [PMID: 37823629 PMCID: PMC10653835 DOI: 10.1128/mbio.01649-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 08/29/2023] [Indexed: 10/13/2023] Open
Abstract
IMPORTANCE To efficiently navigate within the geomagnetic field, magnetotactic bacteria (MTB) align their magnetosome organelles into chains, which are organized by the actin-like MamK protein. Although MamK is the most highly conserved magnetosome protein common to all MTB, its analysis has been confined to a small subgroup owing to the inaccessibility of most MTB. Our study takes advantage of a genetically tractable host where expression of diverse MamK orthologs together with a resurrected MamK LUCA and uncharacterized actin-like Mad28 proteins from deep-branching MTB resulted in gradual restoration of magnetosome chains in various mutants. Our results further indicate the existence of species-specific MamK interactors and shed light on the evolutionary relationships of one of the key proteins associated with bacterial magnetotaxis.
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Affiliation(s)
- Ram Prasad Awal
- Department of Microbiology, Universitat Bayreuth, Bayreuth, Germany
| | - Frank D. Müller
- Department of Microbiology, Universitat Bayreuth, Bayreuth, Germany
| | - Daniel Pfeiffer
- Department of Microbiology, Universitat Bayreuth, Bayreuth, Germany
| | - Caroline L. Monteil
- Aix-Marseille Université, CEA, CNRS, Institute of Biosciences and Biotechnologies of Aix-Marseille, Saint-Paul-lez-Durance, France
| | - Guy Perrière
- Laboratoire de Biométrie et Biologie Evolutive, Université Claude Bernard-Lyon 1, Villeurbanne, France
| | - Christopher T. Lefèvre
- Aix-Marseille Université, CEA, CNRS, Institute of Biosciences and Biotechnologies of Aix-Marseille, Saint-Paul-lez-Durance, France
| | - Dirk Schüler
- Department of Microbiology, Universitat Bayreuth, Bayreuth, Germany
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5
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Parisi M, Lucidi M, Visca P, Cincotti G. Super-Resolution Optical Imaging of Bacterial Cells. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 2023; 29:1-13. [DOI: 10.1109/jstqe.2022.3228121] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2025]
Affiliation(s)
- Miranda Parisi
- Engineering Department, University Roma Tre, Rome, Italy
| | | | - Paolo Visca
- Science Department, University Roma Tre, Rome, Italy
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6
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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: 5] [Impact Index Per Article: 2.5] [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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7
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Zhou Z. Bistability of a helical filament confined on a cylinder. Phys Rev E 2022; 105:024502. [PMID: 35291070 DOI: 10.1103/physreve.105.024502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
The natural configuration of an intrinsically curved and twisted filament is uniquely a helix so that it can be referred to as a helical filament. We find that confining a helical filament on a cylinder can create a bistable state. When c_{0}R=0.5, where c_{0} is the intrinsic curvature of filament and R is the radius of cylinder, the phase diagram for the stability of a helix contains three regimes. Regime I has a small intrinsic twisting rate (ITR) and exhibits a bistable state which consists of two isoenergic helices. In regime II, the filament has a moderate ITR and the bistable state consists of a metastable low-pitch helix and a stable nonhelix. In regime III, the helix is unstable, owing to a large ITR. A similar phenomenon occurs when c_{0}R∼0.5. Monte Carlo simulation confirms these conclusions and indicates further that there are bistable nonhelices in regime III. This bistable system offers a prospective green material since the wide range of parameters and distinctive configurations for bistable states favor its realization and application.
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Affiliation(s)
- Zicong Zhou
- Department of Physics, Tamkang University, 151 Ying-chuan, Tamsui 25137, Taiwan, ROC
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8
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Masson F, Pierrat X, Lemaitre B, Persat A. The wall-less bacterium Spiroplasma poulsonii builds a polymeric cytoskeleton composed of interacting MreB isoforms. iScience 2021; 24:103458. [PMID: 34888500 PMCID: PMC8634037 DOI: 10.1016/j.isci.2021.103458] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/03/2021] [Accepted: 11/11/2021] [Indexed: 11/20/2022] Open
Abstract
A rigid cell wall defines the morphology of most bacteria. MreB, a bacterial homologue of actin, plays a major role in coordinating cell wall biogenesis and defining cell shape. Spiroplasma are wall-less bacteria that robustly grow with a characteristic helical shape. Paradoxal to their lack of cell wall, the Spiroplasma genome contains five homologs of MreB (SpMreBs). Here, we investigate the function of SpMreBs in forming a polymeric cytoskeleton. We found that, in vivo, Spiroplasma maintain a high concentration of all MreB isoforms. By leveraging a heterologous expression system that bypasses the poor genetic tractability of Spiroplasma, we found that SpMreBs produced polymeric filaments of various morphologies. We characterized an interaction network between isoforms that regulate filament formation and patterning. Therefore, our results support the hypothesis where combined SpMreB isoforms would form an inner polymeric cytoskeleton in vivo that shapes the cell in a wall-independent manner. The five Spiroplasma MreB isoforms are extremely abundant proteins in vivo Each isoform produces filaments when expressed in a heterologous system SpMreBs form an interaction network that regulates filament length and shape
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Affiliation(s)
- Florent Masson
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Corresponding author
| | - Xavier Pierrat
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Bruno Lemaitre
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Alexandre Persat
- Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
- Corresponding author
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9
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Sattler L, Graumann PL. Real-Time Messenger RNA Dynamics in Bacillus subtilis. Front Microbiol 2021; 12:760857. [PMID: 34867890 PMCID: PMC8637298 DOI: 10.3389/fmicb.2021.760857] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/08/2021] [Indexed: 11/13/2022] Open
Abstract
Messenger RNA molecules have been localized to different positions in cells and have been followed by time-lapse microscopy. We have used MS2-mVenus-labeled mRNA and single-particle tracking to obtain information on the dynamics of single-mRNA molecules in real time. Using single-molecule tracking, we show that several mRNA molecules visualized via two MS2-binding sites and MS2-mVenus expressed in Bacillus subtilis cells show free diffusion through the entire cell and constrained motion predominantly close to the cell membrane and at the polar regions of the cells. Because constrained motion of mRNAs likely reflects molecules complexed with ribosomes, our data support the idea that translation occurs at sites surrounding the nucleoids. Squared displacement analyses show the existence of at least two distinct populations of molecules with different diffusion constants or possibly of three populations, for example, freely mobile mRNAs, mRNAs in transition complexes, or in complex with polysomes. Diffusion constants between differently sized mRNAs did not differ dramatically and were much lower than that of cytosolic proteins. These data agree with the large size of mRNA molecules and suggest that, within the viscous cytoplasm, size variations do not translate into mobility differences. However, at observed diffusion constants, mRNA molecules would be able to reach all positions within cells in a frame of seconds. We did not observe strong differences in the location of confined motion for mRNAs encoding mostly soluble or membrane proteins, indicating that there is no strong bias for localization of membrane protein-encoding transcripts for the cell membrane.
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Affiliation(s)
- Laura Sattler
- Centre for Synthetic Microbiology (SYNMIKRO) and Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | - Peter L Graumann
- Centre for Synthetic Microbiology (SYNMIKRO) and Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
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10
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Maria Ranieri A, Vezzelli M, Leslie KG, Huang S, Stagni S, Jacquemin D, Jiang H, Hubbard A, Rigamonti L, Watkin ELJ, Ogden MI, New EJ, Massi M. Structure illumination microscopy imaging of lipid vesicles in live bacteria with naphthalimide-appended organometallic complexes. Analyst 2021; 146:3818-3822. [PMID: 34036982 DOI: 10.1039/d1an00363a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
There is a lack of molecular probes for imaging bacteria, in comparison to the array of such tools available for the imaging of mammalian cells. Here, organometallic molecular probes have been developed and assessed for bacterial imaging, designed to have the potential to support multiple imaging modalities. The chemical structure of the probes is designed around a metal-naphthalimide structure. The 4-amino-1,8-naphthalimide moiety, covalently appended through a pyridine ancillary ligand, acts as a luminescent probe for super-resolution microscopy. On the other hand, the metal centre, rhenium(i) or platinum(ii) in the current study, enables techniques such as nanoSIMS. While the rhenium(i) complex was not sufficiently stable to be used as a probe, the platinum(ii) analogue showed good chemical and biological stability. Structured illumination microscopy (SIM) imaging on live Bacillus cereus confirmed the suitability of the probe for super-resolution microscopy. NanoSIMS analysis was used to monitor the uptake of the platinum(ii) complex within the bacteria and demonstrate the potential of this chemical architecture to enable multimodal imaging. The successful combination of these two moieties introduces a platform that could lead to a versatile range of multi-functional probes for bacteria.
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Affiliation(s)
- Anna Maria Ranieri
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
| | - Matteo Vezzelli
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Kathryn G Leslie
- School of Chemistry, The University of Sydney, 2006 NSW, Australia.
| | - Song Huang
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Stefano Stagni
- Dipartimento di Chimica Industriale "Toso Montanari", Università degli Studi di Bologna, viale del Risorgimento 4, 40136 Bologna, Italy
| | - Denis Jacquemin
- Laboratoire CEISAM, UMR CNRS 6230, Universit8 de Nantes, 2 Rue de la HoussiniHre, BP 92208, 44322 Nantes Cedex 3, France
| | - Haibo Jiang
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Alysia Hubbard
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Luca Rigamonti
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Elizabeth L J Watkin
- Curtin Medical School, Curtin University, Kent Street, Bentley 6102 WA, Australia
| | - Mark I Ogden
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
| | - Elizabeth J New
- School of Chemistry, The University of Sydney, 2006 NSW, Australia.
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
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11
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Frare C, Drew KL. Seasonal changes in adenosine kinase in tanycytes of the Arctic ground squirrel (Urocitellus parryii). J Chem Neuroanat 2021; 113:101920. [PMID: 33515665 PMCID: PMC8091519 DOI: 10.1016/j.jchemneu.2021.101920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 12/29/2020] [Accepted: 01/18/2021] [Indexed: 10/22/2022]
Abstract
Hibernation is a seasonal strategy to conserve energy, characterized by modified thermoregulation, an increase in sleep pressure and drastic metabolic changes. Glial cells such as astrocytes and tanycytes are the brain metabolic sensors, but it remains unknown whether they contribute to seasonal expression of hibernation. The onset of hibernation is controlled by an undefined endogenous circannual rhythm in which adenosine plays a role through the activation of the A1 adenosine receptor (A1AR). Seasonal changes in brain levels of adenosine may contribute to an increase in A1AR sensitivity leading to the onset of hibernation. The primary regulator of extracellular adenosine concentration is adenosine kinase, which is located in astrocytes. Using immunohistochemistry to localize and quantify adenosine kinase in Arctic ground squirrels' brain collected during different seasons, we report lower expression of adenosine kinase in the third ventricle tanycytes in winter compared to summer; a similar change was not seen in astrocytes. Moreover, for the first time, we describe adenosine kinase expression in tanycyte cell bodies in the hypothalamus and in the area postrema, both brain regions involved in energy homeostasis. Next we describe seasonal changes in tanycyte morphology in the hypothalamus. Although still speculative, our findings contribute to a model whereby adenosine kinase in tanycytes regulates seasonal changes in extracellular concentration of adenosine underling the seasonal expression of hibernation.
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Affiliation(s)
- C Frare
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA
| | - K L Drew
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, 900 Yukon Drive Rm. 194, Fairbanks, AK 99775-6160, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, 2140 Koyukuk Drive, Fairbanks, AK 99775-7000 USA.
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12
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Hinzke T, Kleiner M, Meister M, Schlüter R, Hentschker C, Pané-Farré J, Hildebrandt P, Felbeck H, Sievert SM, Bonn F, Völker U, Becher D, Schweder T, Markert S. Bacterial symbiont subpopulations have different roles in a deep-sea symbiosis. eLife 2021; 10:58371. [PMID: 33404502 PMCID: PMC7787665 DOI: 10.7554/elife.58371] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 12/05/2020] [Indexed: 12/13/2022] Open
Abstract
The hydrothermal vent tubeworm Riftia pachyptila hosts a single 16S rRNA phylotype of intracellular sulfur-oxidizing symbionts, which vary considerably in cell morphology and exhibit a remarkable degree of physiological diversity and redundancy, even in the same host. To elucidate whether multiple metabolic routes are employed in the same cells or rather in distinct symbiont subpopulations, we enriched symbionts according to cell size by density gradient centrifugation. Metaproteomic analysis, microscopy, and flow cytometry strongly suggest that Riftia symbiont cells of different sizes represent metabolically dissimilar stages of a physiological differentiation process: While small symbionts actively divide and may establish cellular symbiont-host interaction, large symbionts apparently do not divide, but still replicate DNA, leading to DNA endoreduplication. Moreover, in large symbionts, carbon fixation and biomass production seem to be metabolic priorities. We propose that this division of labor between smaller and larger symbionts benefits the productivity of the symbiosis as a whole.
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Affiliation(s)
- Tjorven Hinzke
- Institute of Pharmacy, University of Greifswald, Greifswald, Germany.,Institute of Marine Biotechnology, Greifswald, Germany.,Energy Bioengineering Group, University of Calgary, Calgary, Canada
| | - Manuel Kleiner
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, United States
| | - Mareike Meister
- Institute of Microbiology, University of Greifswald, Greifswald, Germany.,Leibniz Institute for Plasma Science and Technology, Greifswald, Germany
| | - Rabea Schlüter
- Imaging Center of the Department of Biology, University of Greifswald, Greifswald, Germany
| | - Christian Hentschker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Jan Pané-Farré
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-University Marburg, Marburg, Germany
| | - Petra Hildebrandt
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Horst Felbeck
- Scripps Institution of Oceanography, University of California San Diego, San Diego, United States
| | - Stefan M Sievert
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, United States
| | - Florian Bonn
- Institute of Biochemistry, University Hospital, Goethe University School of Medicine Frankfurt, Frankfurt, Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Dörte Becher
- Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Thomas Schweder
- Institute of Pharmacy, University of Greifswald, Greifswald, Germany.,Institute of Marine Biotechnology, Greifswald, Germany
| | - Stephanie Markert
- Institute of Pharmacy, University of Greifswald, Greifswald, Germany.,Institute of Marine Biotechnology, Greifswald, Germany
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13
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Cambré A, Aertsen A. Bacterial Vivisection: How Fluorescence-Based Imaging Techniques Shed a Light on the Inner Workings of Bacteria. Microbiol Mol Biol Rev 2020; 84:e00008-20. [PMID: 33115939 PMCID: PMC7599038 DOI: 10.1128/mmbr.00008-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The rise in fluorescence-based imaging techniques over the past 3 decades has improved the ability of researchers to scrutinize live cell biology at increased spatial and temporal resolution. In microbiology, these real-time vivisections structurally changed the view on the bacterial cell away from the "watery bag of enzymes" paradigm toward the perspective that these organisms are as complex as their eukaryotic counterparts. Capitalizing on the enormous potential of (time-lapse) fluorescence microscopy and the ever-extending pallet of corresponding probes, initial breakthroughs were made in unraveling the localization of proteins and monitoring real-time gene expression. However, later it became clear that the potential of this technique extends much further, paving the way for a focus-shift from observing single events within bacterial cells or populations to obtaining a more global picture at the intra- and intercellular level. In this review, we outline the current state of the art in fluorescence-based vivisection of bacteria and provide an overview of important case studies to exemplify how to use or combine different strategies to gain detailed information on the cell's physiology. The manuscript therefore consists of two separate (but interconnected) parts that can be read and consulted individually. The first part focuses on the fluorescent probe pallet and provides a perspective on modern methodologies for microscopy using these tools. The second section of the review takes the reader on a tour through the bacterial cell from cytoplasm to outer shell, describing strategies and methods to highlight architectural features and overall dynamics within cells.
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Affiliation(s)
- Alexander Cambré
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Leuven, Belgium
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14
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Dersch S, Reimold C, Stoll J, Breddermann H, Heimerl T, Defeu Soufo HJ, Graumann PL. Polymerization of Bacillus subtilis MreB on a lipid membrane reveals lateral co-polymerization of MreB paralogs and strong effects of cations on filament formation. BMC Mol Cell Biol 2020; 21:76. [PMID: 33148162 PMCID: PMC7641798 DOI: 10.1186/s12860-020-00319-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 10/18/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND MreB is a bacterial ortholog of actin and forms mobile filaments underneath the cell membrane, perpendicular to the long axis of the cell, which play a crucial role for cell shape maintenance. We wished to visualize Bacillus subtilis MreB in vitro and therefore established a protocol to obtain monomeric protein, which could be polymerized on a planar membrane system, or associated with large membrane vesicles. RESULTS Using a planar membrane system and electron microscopy, we show that Bacillus subtilis MreB forms bundles of filaments, which can branch and fuse, with an average width of 70 nm. Fluorescence microscopy of non-polymerized YFP-MreB, CFP-Mbl and mCherry-MreBH proteins showed uniform binding to the membrane, suggesting that 2D diffusion along the membrane could facilitate filament formation. After addition of divalent magnesium and calcium ions, all three proteins formed highly disordered sheets of filaments that could split up or merge, such that at high protein concentration, MreB and its paralogs generated a network of filaments extending away from the membrane. Filament formation was positively affected by divalent ions and negatively by monovalent ions. YFP-MreB or CFP-Mbl also formed filaments between two adjacent membranes, which frequently has a curved appearance. New MreB, Mbl or MreBH monomers could add to the lateral side of preexisting filaments, and MreB paralogs co-polymerized, indicating direct lateral interaction between MreB paralogs. CONCLUSIONS Our data show that B. subtilis MreB paralogs do not easily form ordered filaments in vitro, possibly due to extensive lateral contacts, but can co-polymerise. Monomeric MreB, Mbl and MreBH uniformly bind to a membrane, and form irregular and frequently split up filamentous structures, facilitated by the addition of divalent ions, and counteracted by monovalent ions, suggesting that intracellular potassium levels may be one important factor to counteract extensive filament formation and filament splitting in vivo.
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Affiliation(s)
- Simon Dersch
- Centre for Synthetic Microbiology (SYNMIKRO) Hans-Meerwein Strasse 6, Philipps-Universität Marburg, 35032, Marburg, Germany.,Fachbereich Chemie, Hans-Meerwein Strasse, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Christian Reimold
- Centre for Synthetic Microbiology (SYNMIKRO) Hans-Meerwein Strasse 6, Philipps-Universität Marburg, 35032, Marburg, Germany.,Fachbereich Chemie, Hans-Meerwein Strasse, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Joshua Stoll
- Centre for Synthetic Microbiology (SYNMIKRO) Hans-Meerwein Strasse 6, Philipps-Universität Marburg, 35032, Marburg, Germany.,Fachbereich Chemie, Hans-Meerwein Strasse, Philipps-Universität Marburg, 35032, Marburg, Germany
| | | | - Thomas Heimerl
- Centre for Synthetic Microbiology (SYNMIKRO) Hans-Meerwein Strasse 6, Philipps-Universität Marburg, 35032, Marburg, Germany.,Fachbereich Biologie, Karl-von-Frisch-Straße 10, Philipps-Universität Marburg, 35032, Marburg, Germany
| | - Hervé Joel Defeu Soufo
- Department of Microsystems Engineering - IMTEK, University of Freiburg, 79110, Freiburg, Germany
| | - Peter L Graumann
- Centre for Synthetic Microbiology (SYNMIKRO) Hans-Meerwein Strasse 6, Philipps-Universität Marburg, 35032, Marburg, Germany. .,Fachbereich Chemie, Hans-Meerwein Strasse, Philipps-Universität Marburg, 35032, Marburg, Germany.
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15
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Dersch S, Mehl J, Stuckenschneider L, Mayer B, Roth J, Rohrbach A, Graumann PL. Super-Resolution Microscopy and Single-Molecule Tracking Reveal Distinct Adaptive Dynamics of MreB and of Cell Wall-Synthesis Enzymes. Front Microbiol 2020; 11:1946. [PMID: 32973704 PMCID: PMC7468405 DOI: 10.3389/fmicb.2020.01946] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Accepted: 07/23/2020] [Indexed: 11/23/2022] Open
Abstract
The movement of filamentous, actin-like MreB and of enzymes synthesizing the bacterial cell wall has been proposed to be highly coordinated. We have investigated the motion of MreB and of RodA and PbpH cell wall synthesis enzymes at 500 ms and at 20 ms time scales, allowing us to compare the motion of entire MreB filaments as well as of single molecules with that of the two synthesis proteins. While all three proteins formed assemblies that move with very similar trajectory orientation and with similar velocities, their trajectory lengths differed considerably, with PbpH showing shortest and MreB longest trajectories. These experiments suggest different on/off rates for RodA and PbpH at the putative peptidoglycan-extending machinery (PGEM), and during interaction with MreB filaments. Single molecule tracking revealed distinct slow-moving and freely diffusing populations of PbpH and RodA, indicating that they change between free diffusion and slow motion, indicating a dynamic interaction with the PGEM complex. Dynamics of MreB molecules and the orientation and speed of filaments changed markedly after induction of salt stress, while there was little change for RodA and PbpH single molecule dynamics. During the stress adaptation phase, cells continued to grow and extended the cell wall, while MreB formed fewer and more static filaments. Our results show that cell wall synthesis during stress adaptation occurs in a mode involving adaptation of MreB dynamics, and indicate that Bacillus subtilis cell wall extension involves an interplay of enzymes with distinct binding kinetics to sites of active synthesis.
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Affiliation(s)
- Simon Dersch
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Univetsität Marburg, Marburg, Germany
- Fachbereich Chemie, Philipps-Univetsität Marburg, Marburg, Germany
| | - Johanna Mehl
- Laboratory for Bio- and Nano-Photonics, Department of Microsystems Engineering-IMTEK, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Lisa Stuckenschneider
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Univetsität Marburg, Marburg, Germany
- Fachbereich Chemie, Philipps-Univetsität Marburg, Marburg, Germany
| | - Benjamin Mayer
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Univetsität Marburg, Marburg, Germany
- Fachbereich Chemie, Philipps-Univetsität Marburg, Marburg, Germany
| | - Julian Roth
- Laboratory for Bio- and Nano-Photonics, Department of Microsystems Engineering-IMTEK, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Alexander Rohrbach
- Laboratory for Bio- and Nano-Photonics, Department of Microsystems Engineering-IMTEK, BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter L. Graumann
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, Philipps-Univetsität Marburg, Marburg, Germany
- Fachbereich Chemie, Philipps-Univetsität Marburg, Marburg, Germany
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16
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He X, Yang Y, Song H, Wang S, Zhao H, Wei D. Polyanionic Composite Membranes Based on Bacterial Cellulose and Amino Acid for Antimicrobial Application. ACS APPLIED MATERIALS & INTERFACES 2020; 12:14784-14796. [PMID: 32141282 DOI: 10.1021/acsami.9b20733] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ideal wound dressing materials should be active components in the healing process. Bacterial cellulose (BC) has attracted a great deal of attention as novel wound dressing materials; however, it has no intrinsic antimicrobial activity. To explore the practical application values of BC and develop novel wound dressing materials, a series of composite membranes based on BC and polymeric ionic liquids (BC/PILs, composed of BC, and PILs formed by choline and different amino acids) with antimicrobial activity were synthesized by an ex situ method. The physicochemical and antimicrobial properties and biocompatibility of these membranes were systematically investigated. The results indicated that BC/PIL membranes with excellent properties could be obtained by adjusting the concentration and type of PILs. Several kinds of BC/PIL membranes exhibited good biocompatibility and high antimicrobial activity against Gram-positive and Gram-negative bacteria and fungus. The anionic PILs played important roles in the antimicrobial activity of BC/PIL membranes. The obtained membranes provided a novel promising candidate for wound dressing materials.
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Affiliation(s)
- Xiaoling He
- State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Chemistry and Chemical Engineering, Tiangong University, Tianjin 300387, China
| | - Yuqing Yang
- State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Chemistry and Chemical Engineering, Tiangong University, Tianjin 300387, China
| | - Haode Song
- State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Chemistry and Chemical Engineering, Tiangong University, Tianjin 300387, China
| | - Shuai Wang
- State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Chemistry and Chemical Engineering, Tiangong University, Tianjin 300387, China
| | - He Zhao
- State Key Laboratory of Hollow Fiber Membrane Materials and Processes, School of Chemistry and Chemical Engineering, Tiangong University, Tianjin 300387, China
| | - Dongsheng Wei
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, China
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17
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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: 18] [Impact Index Per Article: 3.6] [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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18
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Rani G, Patri I. Importance of being cross-linked for the bacterial cell wall. Phys Rev E 2019; 100:062408. [PMID: 31962385 DOI: 10.1103/physreve.100.062408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Indexed: 06/10/2023]
Abstract
The bacterial cell wall is primarily composed of a mesh of glycan strands cross-linked by peptide bridges and is essential for safeguarding the cell. The structure of the cell wall has to be stiff enough to bear the high turgor pressure and sufficiently tough to ensure protection against failure. Here we explore the role of various design features of the cell in enhancing the toughness of the cell wall. We explain how the glycan strand length distribution, the degree of cross-linking and the placement of the cross-links on the glycan strands can act in tandem to ensure that the cell wall offers sufficient resistance to propagation of cracks. Further, we suggest a possible mechanism by which peptide bond hydrolysis, via judicious cleaving of peptide cross-links, can act to mitigate this risk of failure. We also study the reinforcing effect of MreB cytoskeleton, which can offer a degree of safety to the cell wall. However, we show that the cross-linked structure of the cell wall is its primary line of defense against mechanical failure.
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Affiliation(s)
- Garima Rani
- Institute of Mathematical Sciences, C I T Campus, Chennai 600 113, India
- Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India
| | - Issan Patri
- Chennai Mathematical Institute, SIPCOT IT Park, Siruseri, Chennai 603103, India
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19
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Wong F, Garner EC, Amir A. Mechanics and dynamics of translocating MreB filaments on curved membranes. eLife 2019; 8:40472. [PMID: 30775967 PMCID: PMC6504236 DOI: 10.7554/elife.40472] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 02/15/2019] [Indexed: 12/14/2022] Open
Abstract
MreB is an actin homolog that is essential for coordinating the cell wall synthesis required for the rod shape of many bacteria. Previously we have shown that filaments of MreB bind to the curved membranes of bacteria and translocate in directions determined by principal membrane curvatures to create and reinforce the rod shape (Hussain et al., 2018). Here, in order to understand how MreB filament dynamics affects their cellular distribution, we model how MreB filaments bind and translocate on membranes with different geometries. We find that it is both energetically favorable and robust for filaments to bind and orient along directions of largest membrane curvature. Furthermore, significant localization to different membrane regions results from processive MreB motion in various geometries. These results demonstrate that the in vivo localization of MreB observed in many different experiments, including those examining negative Gaussian curvature, can arise from translocation dynamics alone.
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Affiliation(s)
- Felix Wong
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, United States.,Center for Systems Biology, Harvard University, Cambridge, United States
| | - Ariel Amir
- John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, United States
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20
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Wheeler NE, Blackmore T, Reynolds AD, Midwinter AC, Marshall J, French NP, Savoian MS, Gardner PP, Biggs PJ. Genomic correlates of extraintestinal infection are linked with changes in cell morphology in Campylobacter jejuni. Microb Genom 2019; 5:e000251. [PMID: 30777818 PMCID: PMC6421344 DOI: 10.1099/mgen.0.000251] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 12/16/2018] [Indexed: 12/12/2022] Open
Abstract
Campylobacter jejuni is the most common cause of bacterial diarrheal disease in the world. Clinical outcomes of infection can range from asymptomatic infection to life-threatening extraintestinal infections. This variability in outcomes for infected patients has raised questions as to whether genetic differences between C. jejuni isolates contribute to their likelihood of causing severe disease. In this study, we compare the genomes of ten C. jejuni isolates that were implicated in extraintestinal infections with reference gastrointestinal isolates, in order to identify unusual patterns of sequence variation associated with infection outcome. We identified a collection of genes that display a higher burden of uncommon mutations in invasive isolates compared with gastrointestinal close relatives, including some that have been previously linked to virulence and invasiveness in C. jejuni. Among the top genes identified were mreB and pgp1, which are both involved in determining cell shape. Electron microscopy confirmed morphological differences in isolates carrying unusual sequence variants of these genes, indicating a possible relationship between extraintestinal infection and changes in cell morphology.
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Affiliation(s)
- Nicole E. Wheeler
- Center for Genomic Pathogen Surveillance, Wellcome Sanger Institute, Hinxton, UK
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
| | | | - Angela D. Reynolds
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Anne C. Midwinter
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Jonathan Marshall
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Nigel P. French
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
- New Zealand Food Safety Science and Research Centre, Palmerston North, New Zealand
| | - Matthew S. Savoian
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Paul P. Gardner
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Biomolecular Interaction Centre, University of Canterbury, Christchurch, New Zealand
- Department of Biochemistry, University of Otago, Dunedin, New Zealand.
| | - Patrick J. Biggs
- EpiLab, School of Veterinary Science, Massey University, Palmerston North, New Zealand
- New Zealand Genomics Ltd (NZGL – as Massey Genome Service) Massey University, Palmerston North, New Zealand
- Allan Wilson Centre for Molecular Ecology and Evolution, Massey University, Palmerston North, New Zealand
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21
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Abstract
The construction of the bacterial cell envelope is a fundamental topic, as it confers its integrity to bacteria and is consequently the target of numerous antibiotics. MreB is an essential protein suspected to regulate the cell wall synthetic machineries. Despite two decades of study, its localization remains the subject of controversies, its description ranging from helical filaments spanning the entire cell to small discrete entities. The true structure of these filaments is important because it impacts the model describing how the machineries building the cell wall are associated, how they are coordinated at the scale of the entire cell, and how MreB mediates this regulation. Our results shed light on this debate, revealing the size of native filaments in B. subtilis during growth. They argue against models where MreB filament size directly affects the speed of synthesis of the cell wall and where MreB would coordinate distant machineries along the side wall. The actin-like MreB protein is a key player of the machinery controlling the elongation and maintenance of the cell shape of most rod-shaped bacteria. This protein is known to be highly dynamic, moving along the short axis of cells, presumably reflecting the movement of cell wall synthetic machineries during the enzymatic assembly of the peptidoglycan mesh. The ability of MreB proteins to form polymers is not debated, but their structure, length, and conditions of establishment have remained unclear and the subject of conflicting reports. Here we analyze various strains of Bacillus subtilis, the model for Gram-positive bacteria, and we show that MreB forms subdiffraction-limited, less than 200 nm-long nanofilaments on average during active growth, while micron-long filaments are a consequence of artificial overaccumulation of the protein. Our results also show the absence of impact of the size of the filaments on their speed, orientation, and other dynamic properties conferring a large tolerance to B. subtilis toward the levels and consequently the lengths of MreB polymers. Our data indicate that the density of mobile filaments remains constant in various strains regardless of their MreB levels, suggesting that another factor determines this constant.
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22
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Shi H, Bratton BP, Gitai Z, Huang KC. How to Build a Bacterial Cell: MreB as the Foreman of E. coli Construction. Cell 2019. [PMID: 29522748 DOI: 10.1016/j.cell.2018.02.050] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cell shape matters across the kingdoms of life, and cells have the remarkable capacity to define and maintain specific shapes and sizes. But how are the shapes of micron-sized cells determined from the coordinated activities of nanometer-sized proteins? Here, we review general principles that have surfaced through the study of rod-shaped bacterial growth. Imaging approaches have revealed that polymers of the actin homolog MreB play a central role. MreB both senses and changes cell shape, thereby generating a self-organizing feedback system for shape maintenance. At the molecular level, structural and computational studies indicate that MreB filaments exhibit tunable mechanical properties that explain their preference for certain geometries and orientations along the cylindrical cell body. We illustrate the regulatory landscape of rod-shape formation and the connectivity between cell shape, cell growth, and other aspects of cell physiology. These discoveries provide a framework for future investigations into the architecture and construction of microbes.
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Affiliation(s)
- Handuo Shi
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Benjamin P Bratton
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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23
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Rösch TC, Oviedo-Bocanegra LM, Fritz G, Graumann PL. SMTracker: a tool for quantitative analysis, exploration and visualization of single-molecule tracking data reveals highly dynamic binding of B. subtilis global repressor AbrB throughout the genome. Sci Rep 2018; 8:15747. [PMID: 30356068 PMCID: PMC6200787 DOI: 10.1038/s41598-018-33842-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/02/2018] [Indexed: 01/08/2023] Open
Abstract
Single-particle (molecule) tracking (SPT/SMT) is a powerful method to study dynamic processes in living cells at high spatial and temporal resolution. Even though SMT is becoming a widely used method in bacterial cell biology, there is no program employing different analytical tools for the quantitative evaluation of tracking data. We developed SMTracker, a MATLAB-based graphical user interface (GUI) for automatically quantifying, visualizing and managing SMT data via five interactive panels, allowing the user to interactively explore tracking data from several conditions, movies and cells on a track-by-track basis. Diffusion constants are calculated a) by a Gaussian mixture model (GMM) panel, analyzing the distribution of positional displacements in x- and y-direction using a multi-state diffusion model (e.g. DNA-bound vs. freely diffusing molecules), and inferring the diffusion constants and relative fraction of molecules in each state, or b) by square displacement analysis (SQD), using the cumulative probability distribution of square displacements to estimate the diffusion constants and relative fractions of up to three diffusive states, or c) through mean-squared displacement (MSD) analyses, allowing the discrimination between Brownian, sub- or superdiffusive behavior. A spatial distribution analysis (SDA) panel analyzes the subcellular localization of molecules, summarizing the localization of trajectories in 2D- heat maps. Using SMTracker, we show that the global transcriptional repressor AbrB performs highly dynamic binding throughout the Bacillus subtilis genome, with short dwell times that indicate high on/off rates in vivo. While about a third of AbrB molecules are in a DNA-bound state, 40% diffuse through the chromosome, and the remaining molecules freely diffuse through the cells. AbrB also forms one or two regions of high intensity binding on the nucleoids, similar to the global gene silencer H-NS in Escherichia coli, indicating that AbrB may also confer a structural function in genome organization.
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Affiliation(s)
- Thomas C Rösch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Luis M Oviedo-Bocanegra
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany.,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Georg Fritz
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany. .,Department of Physics, Philipps Universität Marburg, Marburg, Germany.
| | - Peter L Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Marburg, Germany. .,Department of Chemistry, Philipps Universität Marburg, Marburg, Germany.
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24
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Fu G, Bandaria JN, Le Gall AV, Fan X, Yildiz A, Mignot T, Zusman DR, Nan B. MotAB-like machinery drives the movement of MreB filaments during bacterial gliding motility. Proc Natl Acad Sci U S A 2018; 115:2484-2489. [PMID: 29463706 PMCID: PMC5877941 DOI: 10.1073/pnas.1716441115] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
MreB is a bacterial actin that is important for cell shape and cell wall biosynthesis in many bacterial species. MreB also plays crucial roles in Myxococcus xanthus gliding motility, but the underlying mechanism remains unknown. Here we tracked the dynamics of single MreB particles in M. xanthus using single-particle tracking photoactivated localization microscopy. We found that a subpopulation of MreB particles moves rapidly along helical trajectories, similar to the movements of the MotAB-like gliding motors. The rapid MreB motion was stalled in the mutants that carried truncated gliding motors. Remarkably, M. xanthus MreB moves one to two orders of magnitude faster than its homologs that move along with the cell wall synthesis machinery in Bacillus subtilis and Escherichia coli, and this rapid movement was not affected by the inhibitors of cell wall biosynthesis. Our results show that in M. xanthus, MreB provides a scaffold for the gliding motors while the gliding machinery drives the movement of MreB filaments, analogous to the interdependent movements of myosin motors and actin in eukaryotic cells.
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Affiliation(s)
- Guo Fu
- Department of Biology, Texas A&M University, College Station, TX 77843
| | - Jigar N Bandaria
- Department of Physics, University of California, Berkeley, CA 94720
| | - Anne Valérie Le Gall
- Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille University, 13009 Marseille, France
| | - Xue Fan
- Department of Statistics, Texas A&M University, College Station, TX 77843
| | - Ahmet Yildiz
- Department of Physics, University of California, Berkeley, CA 94720
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, UMR7283, Institut de Microbiologie de la Méditerranée, CNRS-Aix Marseille University, 13009 Marseille, France
| | - David R Zusman
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX 77843;
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25
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van Teeffelen S, Renner LD. Recent advances in understanding how rod-like bacteria stably maintain their cell shapes. F1000Res 2018; 7:241. [PMID: 29560261 PMCID: PMC5832919 DOI: 10.12688/f1000research.12663.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/22/2018] [Indexed: 01/14/2023] Open
Abstract
Cell shape and cell volume are important for many bacterial functions. In recent years, we have seen a range of experimental and theoretical work that led to a better understanding of the determinants of cell shape and size. The roles of different molecular machineries for cell-wall expansion have been detailed and partially redefined, mechanical forces have been shown to influence cell shape, and new connections between metabolism and cell shape have been proposed. Yet the fundamental determinants of the different cellular dimensions remain to be identified. Here, we highlight some of the recent developments and focus on the determinants of rod-like cell shape and size in the well-studied model organisms
Escherichia coli and
Bacillus subtilis.
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Affiliation(s)
- Sven van Teeffelen
- Department of Microbiology, Institut Pasteur, 75724 Paris Cedex 15, France
| | - Lars D Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, 01069 Dresden, Germany
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26
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Weihs F, Wacnik K, Turner RD, Culley S, Henriques R, Foster SJ. Heterogeneous localisation of membrane proteins in Staphylococcus aureus. Sci Rep 2018; 8:3657. [PMID: 29483609 PMCID: PMC5826919 DOI: 10.1038/s41598-018-21750-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/08/2018] [Indexed: 11/25/2022] Open
Abstract
The bacterial cytoplasmic membrane is the interface between the cell and its environment, with multiple membrane proteins serving its many functions. However, how these proteins are organised to permit optimal physiological processes is largely unknown. Based on our initial findings that 2 phospholipid biosynthetic enzymes (PlsY and CdsA) localise heterogeneously in the membrane of the bacterium Staphylococcus aureus, we have analysed the localisation of other key membrane proteins. A range of protein fusions were constructed and used in conjunction with quantitative image analysis. Enzymes involved in phospholipid biosynthesis as well as the lipid raft marker FloT exhibited a heterogeneous localisation pattern. However, the secretion associated SecY protein, was more homogeneously distributed in the membrane. A FRET-based system also identified novel colocalisation between phospholipid biosynthesis enzymes and the respiratory protein CydB revealing a likely larger network of partners. PlsY localisation was found to be dose dependent but not to be affected by membrane lipid composition. Disruption of the activity of the essential cell division organiser FtsZ, using the inhibitor PC190723 led to loss of PlsY localisation, revealing a link to cell division and a possible role for FtsZ in functions not strictly associated with septum formation.
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Affiliation(s)
- Felix Weihs
- The Krebs Institute. Department of Molecular Biology and Microbiology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Katarzyna Wacnik
- The Krebs Institute. Department of Molecular Biology and Microbiology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Robert D Turner
- The Krebs Institute. Department of Molecular Biology and Microbiology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Siân Culley
- Quantitative Imaging and Nanobiophysics Group, MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK
| | - Ricardo Henriques
- Quantitative Imaging and Nanobiophysics Group, MRC Laboratory for Molecular Cell Biology and Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- The Francis Crick Institute, 1 Midland Rd, Kings Cross, London, NW1 1AT, UK
| | - Simon J Foster
- The Krebs Institute. Department of Molecular Biology and Microbiology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK.
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27
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Dersch S, Graumann PL. The ultimate picture-the combination of live cell superresolution microscopy and single molecule tracking yields highest spatio-temporal resolution. Curr Opin Microbiol 2017; 43:55-61. [PMID: 29227820 DOI: 10.1016/j.mib.2017.11.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 12/15/2022]
Abstract
We are witnessing a breathtaking development in light (fluorescence) microscopy, where structures can be resolved down to the size of a ribosome within cells. This has already yielded surprising insight into the subcellular structure of cells, including the smallest cells, bacteria. Moreover, it has become possible to visualize and track single fluorescent protein fusions in real time, and quantify molecule numbers within individual cells. Combined, super resolution and single molecule tracking are pushing the limits of our understanding of the spatio-temporal organization even of the smallest cells to an unprecedented depth.
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Affiliation(s)
- Simon Dersch
- Centre for Synthetic Microbiology (SYNMIKRO), and Fachbereich Chemie, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Peter L Graumann
- Centre for Synthetic Microbiology (SYNMIKRO), and Fachbereich Chemie, Philipps-Universität Marburg, 35032 Marburg, Germany.
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28
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Schneider JP, Basler M. Shedding light on biology of bacterial cells. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0499. [PMID: 27672150 PMCID: PMC5052743 DOI: 10.1098/rstb.2015.0499] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2016] [Indexed: 12/11/2022] Open
Abstract
To understand basic principles of living organisms one has to know many different properties of all cellular components, their mutual interactions but also their amounts and spatial organization. Live-cell imaging is one possible approach to obtain such data. To get multiple snapshots of a cellular process, the imaging approach has to be gentle enough to not disrupt basic functions of the cell but also have high temporal and spatial resolution to detect and describe the changes. Light microscopy has become a method of choice and since its early development over 300 years ago revolutionized our understanding of living organisms. As most cellular components are indistinguishable from the rest of the cellular contents, the second revolution came from a discovery of specific labelling techniques, such as fusions to fluorescent proteins that allowed specific tracking of a component of interest. Currently, several different tags can be tracked independently and this allows us to simultaneously monitor the dynamics of several cellular components and from the correlation of their dynamics to infer their respective functions. It is, therefore, not surprising that live-cell fluorescence microscopy significantly advanced our understanding of basic cellular processes. Current cameras are fast enough to detect changes with millisecond time resolution and are sensitive enough to detect even a few photons per pixel. Together with constant improvement of properties of fluorescent tags, it is now possible to track single molecules in living cells over an extended period of time with a great temporal resolution. The parallel development of new illumination and detection techniques allowed breaking the diffraction barrier and thus further pushed the resolution limit of light microscopy. In this review, we would like to cover recent advances in live-cell imaging technology relevant to bacterial cells and provide a few examples of research that has been possible due to imaging. This article is part of the themed issue ‘The new bacteriology’.
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Affiliation(s)
- Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
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29
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Abstract
The bacterial cytoplasmic membrane is composed of roughly equal proportions of lipids and proteins. The main lipid components are phospholipids, which vary in acyl chain length, saturation, and branching and carry head groups that vary in size and charge. Phospholipid variants determine membrane properties such as fluidity and charge that in turn modulate interactions with membrane-associated proteins. We summarize recent advances in understanding bacterial membrane structure and function, focusing particularly on the possible existence and significance of specialized membrane domains. We review the role of membrane curvature as a spatial cue for recruitment and regulation of proteins involved in morphogenic functions, especially elongation and division. Finally, we examine the role of the membrane, especially regulation of synthesis and fluid properties, in the life cycle of cell wall-deficient L-form bacteria.
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Affiliation(s)
- Henrik Strahl
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, NE2 4AX United Kingdom; ,
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, NE2 4AX United Kingdom; ,
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30
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Saurabh S, Perez AM, Comerci CJ, Shapiro L, Moerner WE. Super-Resolution Microscopy and Single-Protein Tracking in Live Bacteria Using a Genetically Encoded, Photostable Fluoromodule. ACTA ACUST UNITED AC 2017. [PMID: 28627757 DOI: 10.1002/cpcb.21] [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: 12/19/2022]
Abstract
Visualization of dynamic protein structures in live cells is crucial for understanding the mechanisms governing biological processes. Fluorescence microscopy is a sensitive tool for this purpose. In order to image proteins in live bacteria using fluorescence microscopy, one typically genetically fuses the protein of interest to a photostable fluorescent tag. Several labeling schemes are available to accomplish this. Particularly, hybrid tags that combine a fluorescent or fluorogenic dye with a genetically encoded protein (such as enzymatic labels) have been used successfully in multiple cell types. However, their use in bacteria has been limited due to challenges imposed by a complex bacterial cell wall. Here, we describe the use of a genetically encoded photostable fluoromodule that can be targeted to cytosolic and membrane proteins in the Gram negative bacterium Caulobacter crescentus. Additionally, we summarize methods to use this fluoromodule for single protein imaging and super-resolution microscopy using stimulated emission depletion. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- Saumya Saurabh
- Department of Chemistry, Stanford University, Stanford, California
| | - Adam M Perez
- Department of Developmental Biology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, Stanford, California.,Department of Biology, Stanford University, Stanford, California
| | - Colin J Comerci
- Biophysics Program, Stanford University, Stanford, California
| | - Lucy Shapiro
- Department of Developmental Biology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, Stanford, California
| | - W E Moerner
- Department of Chemistry, Stanford University, Stanford, California
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31
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Billaudeau C, Chastanet A, Yao Z, Cornilleau C, Mirouze N, Fromion V, Carballido-López R. Contrasting mechanisms of growth in two model rod-shaped bacteria. Nat Commun 2017; 8:15370. [PMID: 28589952 PMCID: PMC5467245 DOI: 10.1038/ncomms15370] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 03/23/2017] [Indexed: 12/24/2022] Open
Abstract
How cells control their shape and size is a long-standing question in cell biology. Many rod-shaped bacteria elongate their sidewalls by the action of cell wall synthesizing machineries that are associated to actin-like MreB cortical patches. However, little is known about how elongation is regulated to enable varied growth rates and sizes. Here we use total internal reflection fluorescence microscopy and single-particle tracking to visualize MreB isoforms, as a proxy for cell wall synthesis, in Bacillus subtilis and Escherichia coli cells growing in different media and during nutrient upshift. We find that these two model organisms appear to use orthogonal strategies to adapt to growth regime variations: B. subtilis regulates MreB patch speed, while E. coli may mainly regulate the production capacity of MreB-associated cell wall machineries. We present numerical models that link MreB-mediated sidewall synthesis and cell elongation, and argue that the distinct regulatory mechanism employed might reflect the different cell wall integrity constraints in Gram-positive and Gram-negative bacteria. Protein MreB participates in elongation of sidewalls during growth of most rod-shaped bacteria. Here, the authors use fluorescence microscopy and single-particle tracking to visualize MreB, showing that Bacillus subtilis and Escherichia coli appear to use different strategies to adapt to growth rate variations.
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Affiliation(s)
- Cyrille Billaudeau
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Arnaud Chastanet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Zhizhong Yao
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Charlène Cornilleau
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Nicolas Mirouze
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Vincent Fromion
- MaIAGE, INRA, Université Paris-Saclay, Jouy-en-Josas F78350, France
| | - Rut Carballido-López
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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32
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Abstract
Bacillus subtilis is the best described member of the Gram positive bacteria. It is a typical rod shaped bacterium and grows by elongation in its long axis, before dividing at mid cell to generate two similar daughter cells. B. subtilis is a particularly interesting model for cell cycle studies because it also carries out a modified, asymmetrical division during endospore formation, which can be simply induced by starvation. Cell growth occurs strictly by elongation of the rod, which maintains a constant diameter at all growth rates. This process involves expansion of the cell wall, requiring intercalation of new peptidoglycan and teichoic acid material, as well as controlled hydrolysis of existing wall material. Actin-like MreB proteins are the key spatial regulators that orchestrate the plethora of enzymes needed for cell elongation, many of which are thought to assemble into functional complexes called elongasomes. Cell division requires a switch in the orientation of cell wall synthesis and is organised by a tubulin-like protein FtsZ. FtsZ forms a ring-like structure at the site of impending division, which is specified by a range of mainly negative regulators. There it recruits a set of dedicated division proteins to form a structure called the divisome, which brings about the process of division. During sporulation, both the positioning and fine structure of the division septum are altered, and again, several dedicated proteins that contribute specifically to this process have been identified. This chapter summarises our current understanding of elongation and division in B. subtilis, with particular emphasis on the cytoskeletal proteins MreB and FtsZ, and highlights where the major gaps in our understanding remain.
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33
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Mukherjee I, Ghosh A, Bhadury P, De P. Side-Chain Amino Acid-Based Cationic Antibacterial Polymers: Investigating the Morphological Switching of a Polymer-Treated Bacterial Cell. ACS OMEGA 2017; 2:1633-1644. [PMID: 30023640 PMCID: PMC6044850 DOI: 10.1021/acsomega.7b00181] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 04/11/2017] [Indexed: 05/21/2023]
Abstract
Synthetic polymer-based antimicrobial materials destroy conventional antibiotic resistant microorganisms. Although these antibacterial polymers imitate the properties of antimicrobial peptides (AMPs), their effect on bacterial cell morphology has not been studied in detail. To investigate the morphology change of a bacterial cell in the presence of antimicrobial polymer, herein we have designed and synthesized side-chain amino acid-based cationic polymers, which showed efficient antibacterial activity against Gram-negative (Escherichia coli), as well as Gram-positive (Bacillus subtilis) bacteria. Morphological switching from a rod shape to a spherical shape of E. coli cells was observed by field emission-scanning electron microscopy analysis due to cell wall disruption, whereas the B. subtilis cell structure and size remained intact, but stacks of the cells formed after polymer treatment. The zone of inhibition experiment on an agar plate for E. coli cells exhibited drastic morphological changes at the vicinity of the polymer-treated portion and somewhat less of an effect at the periphery of the plate.
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Affiliation(s)
- Ishita Mukherjee
- Department
of Chemical Sciences and Department of Biological Sciences, Indian Institute of Science Education and Research
Kolkata, Mohanpur, 741246 Haringhata, Nadia, West
Bengal, India
| | - Anwesha Ghosh
- Department
of Chemical Sciences and Department of Biological Sciences, Indian Institute of Science Education and Research
Kolkata, Mohanpur, 741246 Haringhata, Nadia, West
Bengal, India
| | - Punyasloke Bhadury
- Department
of Chemical Sciences and Department of Biological Sciences, Indian Institute of Science Education and Research
Kolkata, Mohanpur, 741246 Haringhata, Nadia, West
Bengal, India
| | - Priyadarsi De
- Department
of Chemical Sciences and Department of Biological Sciences, Indian Institute of Science Education and Research
Kolkata, Mohanpur, 741246 Haringhata, Nadia, West
Bengal, India
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34
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Kawazura T, Matsumoto K, Kojima K, Kato F, Kanai T, Niki H, Shiomi D. Exclusion of assembled MreB by anionic phospholipids at cell poles confers cell polarity for bidirectional growth. Mol Microbiol 2017; 104:472-486. [PMID: 28164388 DOI: 10.1111/mmi.13639] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2017] [Indexed: 12/21/2022]
Abstract
Cell polarity determines the direction of cell growth in bacteria. MreB actin spatially regulates peptidoglycan synthesis to enable cells to elongate bidirectionally. MreB densely localizes in the cylindrical part of the rod cell and not in polar regions in Escherichia coli. When treated with A22, which inhibits MreB polymerization, rod-shaped cells became round and MreB was diffusely distributed throughout the cytoplasmic membrane. A22 removal resulted in restoration of the rod shape. Initially, diffuse MreB started to re-assemble, and MreB-free zones were subsequently observed in the cytoplasmic membrane. These MreB-free zones finally became cell poles, allowing the cells to elongate bidirectionally. When MreB was artificially located at the cell poles, an additional pole was created, indicating that artificial localization of MreB at the cell pole induced local peptidoglycan synthesis. It was found that the anionic phospholipids (aPLs), phosphatidylglycerol and cardiolipin, which were enriched in cell poles preferentially interact with monomeric MreB compared with assembled MreB in vitro. MreB tended to localize to cell poles in cells lacking both aPLs, resulting in production of Y-shaped cells. Their findings indicated that aPLs exclude assembled MreB from cell poles to establish cell polarity, thereby allowing cells to elongate in a particular direction.
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Affiliation(s)
- Takuma Kawazura
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Kanon Matsumoto
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Koki Kojima
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Fumiya Kato
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Tomomi Kanai
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
| | - Hironori Niki
- Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.,Department of Genetics, The Graduate University for Advanced Studies, Sokendai, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan
| | - Daisuke Shiomi
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan
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35
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Abstract
A diverse set of protein polymers, structurally related to actin filaments contributes to the organization of bacterial cells as cytomotive or cytoskeletal filaments. This chapter describes actin homologs encoded by bacterial chromosomes. MamK filaments, unique to magnetotactic bacteria, help establishing magnetic biological compasses by interacting with magnetosomes. Magnetosomes are intracellular membrane invaginations containing biomineralized crystals of iron oxide that are positioned by MamK along the long-axis of the cell. FtsA is widespread across bacteria and it is one of the earliest components of the divisome to arrive at midcell, where it anchors the cell division machinery to the membrane. FtsA binds directly to FtsZ filaments and to the membrane through its C-terminus. FtsA shows altered domain architecture when compared to the canonical actin fold. FtsA's subdomain 1C replaces subdomain 1B of other members of the actin family and is located on the opposite side of the molecule. Nevertheless, when FtsA assembles into protofilaments, the protofilament structure is preserved, as subdomain 1C replaces subdomain IB of the following subunit in a canonical actin filament. MreB has an essential role in shape-maintenance of most rod-shaped bacteria. Unusually, MreB filaments assemble from two protofilaments in a flat and antiparallel arrangement. This non-polar architecture implies that both MreB filament ends are structurally identical. MreB filaments bind directly to membranes where they interact with both cytosolic and membrane proteins, thereby forming a key component of the elongasome. MreB filaments in cells are short and dynamic, moving around the long axis of rod-shaped cells, sensing curvature of the membrane and being implicated in peptidoglycan synthesis.
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Affiliation(s)
- Thierry Izoré
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Fusinita van den Ent
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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36
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Abstract
As discovered over the past 25 years, the cytoskeletons of bacteria and archaea are complex systems of proteins whose central components are dynamic cytomotive filaments. They perform roles in cell division, DNA partitioning, cell shape determination and the organisation of intracellular components. The protofilament structures and polymerisation activities of various actin-like, tubulin-like and ESCRT-like proteins of prokaryotes closely resemble their eukaryotic counterparts but show greater diversity. Their activities are modulated by a wide range of accessory proteins but these do not include homologues of the motor proteins that supplement filament dynamics to aid eukaryotic cell motility. Numerous other filamentous proteins, some related to eukaryotic IF-proteins/lamins and dynamins etc, seem to perform structural roles similar to those in eukaryotes.
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Affiliation(s)
- Linda A Amos
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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37
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Xiao J, Dufrêne YF. Optical and force nanoscopy in microbiology. Nat Microbiol 2016; 1:16186. [PMID: 27782138 PMCID: PMC5839876 DOI: 10.1038/nmicrobiol.2016.186] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/01/2016] [Indexed: 12/31/2022]
Abstract
Microbial cells have developed sophisticated multicomponent structures and machineries to govern basic cellular processes, such as chromosome segregation, gene expression, cell division, mechanosensing, cell adhesion and biofilm formation. Because of the small cell sizes, subcellular structures have long been difficult to visualize using diffraction-limited light microscopy. During the last three decades, optical and force nanoscopy techniques have been developed to probe intracellular and extracellular structures with unprecedented resolutions, enabling researchers to study their organization, dynamics and interactions in individual cells, at the single-molecule level, from the inside out, and all the way up to cell-cell interactions in microbial communities. In this Review, we discuss the principles, advantages and limitations of the main optical and force nanoscopy techniques available in microbiology, and we highlight some outstanding questions that these new tools may help to answer.
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Affiliation(s)
- Jie Xiao
- Department of Biophysics &Biophysical Chemistry, The Johns Hopkins School of Medicine, 725 N. Wolfe Street, Baltimore, Maryland 21212, USA
| | - Yves F Dufrêne
- Institute of Life Sciences, Université catholique de Louvain, Croix du Sud, 4-5, bte L7.07.06., B-1348 Louvain-la-Neuve, Belgium
- Walloon Excellence in Life sciences and Biotechnology (WELBIO), Belgium
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38
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Ouzounov N, Nguyen JP, Bratton BP, Jacobowitz D, Gitai Z, Shaevitz JW. MreB Orientation Correlates with Cell Diameter in Escherichia coli. Biophys J 2016; 111:1035-43. [PMID: 27602731 PMCID: PMC5018124 DOI: 10.1016/j.bpj.2016.07.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/14/2016] [Accepted: 07/01/2016] [Indexed: 10/21/2022] Open
Abstract
Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter.
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Affiliation(s)
- Nikolay Ouzounov
- Department of Molecular Biology, Princeton University, Princeton, New Jersey
| | - Jeffrey P Nguyen
- Department of Physics, Princeton University, Princeton, New Jersey
| | - Benjamin P Bratton
- Department of Molecular Biology, Princeton University, Princeton, New Jersey; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey
| | - David Jacobowitz
- Department of Physics, Princeton University, Princeton, New Jersey
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, New Jersey
| | - Joshua W Shaevitz
- Department of Physics, Princeton University, Princeton, New Jersey; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey.
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39
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Where are things inside a bacterial cell? Curr Opin Microbiol 2016; 33:83-90. [PMID: 27450542 DOI: 10.1016/j.mib.2016.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 06/21/2016] [Accepted: 07/06/2016] [Indexed: 01/13/2023]
Abstract
Bacterial cells are intricately organized, despite the lack of membrane-bounded organelles. The extremely crowded cytoplasm promotes macromolecular self-assembly and formation of distinct subcellular structures, which perform specialized functions. For example, the cell poles act as hubs for signal transduction complexes, thus providing a platform for the coordination of optimal cellular responses to environmental cues. Distribution of macromolecules is mostly mediated via specialized transport machineries, including the MreB cytoskeleton. Recent evidence shows that RNAs also specifically localize within bacterial cells, raising the possibility that gene expression is spatially organized. Here we review the current understanding of where things are in bacterial cells and discuss emerging questions that need to be addressed in the future.
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40
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Dempwolff F, Schmidt FK, Hervás AB, Stroh A, Rösch TC, Riese CN, Dersch S, Heimerl T, Lucena D, Hülsbusch N, Stuermer CAO, Takeshita N, Fischer R, Eckhardt B, Graumann PL. Super Resolution Fluorescence Microscopy and Tracking of Bacterial Flotillin (Reggie) Paralogs Provide Evidence for Defined-Sized Protein Microdomains within the Bacterial Membrane but Absence of Clusters Containing Detergent-Resistant Proteins. PLoS Genet 2016; 12:e1006116. [PMID: 27362352 PMCID: PMC4928834 DOI: 10.1371/journal.pgen.1006116] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 05/20/2016] [Indexed: 12/14/2022] Open
Abstract
Biological membranes have been proposed to contain microdomains of a specific lipid composition, in which distinct groups of proteins are clustered. Flotillin-like proteins are conserved between pro—and eukaryotes, play an important function in several eukaryotic and bacterial cells, and define in vertebrates a type of so-called detergent-resistant microdomains. Using STED microscopy, we show that two bacterial flotillins, FloA and FloT, form defined assemblies with an average diameter of 85 to 110 nm in the model bacterium Bacillus subtilis. Interestingly, flotillin microdomains are of similar size in eukaryotic cells. The soluble domains of FloA form higher order oligomers of up to several hundred kDa in vitro, showing that like eukaryotic flotillins, bacterial assemblies are based in part on their ability to self-oligomerize. However, B. subtilis paralogs show significantly different diffusion rates, and consequently do not colocalize into a common microdomain. Dual colour time lapse experiments of flotillins together with other detergent-resistant proteins in bacteria show that proteins colocalize for no longer than a few hundred milliseconds, and do not move together. Our data reveal that the bacterial membrane contains defined-sized protein domains rather than functional microdomains dependent on flotillins. Based on their distinct dynamics, FloA and FloT confer spatially distinguishable activities, but do not serve as molecular scaffolds. Many membrane proteins are not uniformly distributed within biological membranes, and may prefer specific lipid environments to function optimally. Using super resolution fluorescence microscopy, we show that several Bacillus subtilis membrane proteins indeed cluster into structures of 60 to 110 nm, verifying the existence of defined-size protein microdomains. Biochemical co-isolation of specific membrane proteins and flotillins, a family of proteins highly conserved between eukaryotic and bacterial cells, suggested that common “functional” microdomains exist, containing so-called “detergent-resistant” membrane proteins, that are centered by flotillins. Through high speed tracking of Bacillus subtilis FloA and FloT we show that both proteins are not present in the same microdomain, but move through the membrane with different velocities. Dual colour time lapse microscopy showed that contrarily to vertebrate flotillins, bacterial flotillins do not move together with detergent-resistant proteins, ruling out the existence of coclusters. The lack of both flotillins, but not of a single one, leads to striking defects in cell shape and in cell growth, indicating important overlapping functions of flotillin paralogs. Our data show that FloA and FloT perform spatially distinct functions, possibly in the insertion of membrane proteins that require a specific lipid environment, based on a close connection between FloA and FloT with the Sec membrane insertion machinery, but do not act as scaffolds for detergent resistant proteins. Our tracking analyses provide an important basis for the understanding of interactions between membrane proteins in living cells.
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Affiliation(s)
- Felix Dempwolff
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Felix K. Schmidt
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Physics, Philipps Universität Marburg, Marburg, Germany
| | - Ana B. Hervás
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Alex Stroh
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Thomas C. Rösch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Cornelius N. Riese
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Biology, Philipps Universität Marburg, Marburg, Germany
| | - Simon Dersch
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Thomas Heimerl
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Biology, Philipps Universität Marburg, Marburg, Germany
| | - Daniella Lucena
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Nikola Hülsbusch
- Department of Biology, University of Konstanz, Konstanz, Germany
| | | | - Norio Takeshita
- University of Tsukuba, Faculty of Life and Environmental Sciences, Tsukuba, Ibaraki, Japan
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Reinhard Fischer
- Department of Microbiology, Institute for Applied Bioscience, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Bruno Eckhardt
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Physics, Philipps Universität Marburg, Marburg, Germany
| | - Peter L. Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, Philipps Universität Marburg, Marburg, Germany
- Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
- * E-mail:
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Abstract
Super resolution imaging is becoming an increasingly important tool in the arsenal of methods available to cell biologists. In recognition of its potential, the Nobel Prize for chemistry was awarded to three investigators involved in the development of super resolution imaging methods in 2014. The availability of commercial instruments for super resolution imaging has further spurred the development of new methods and reagents designed to take advantage of super resolution techniques. Super resolution offers the advantages traditionally associated with light microscopy, including the use of gentle fixation and specimen preparation methods, the ability to visualize multiple elements within a single specimen, and the potential to visualize dynamic changes in living specimens over time. However, imaging of living cells over time is difficult and super resolution imaging is computationally demanding. In this review, we discuss the advantages/disadvantages of different super resolution systems for imaging fixed live specimens, with particular regard to cytoskeleton structures.
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Affiliation(s)
- Eric A Shelden
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
| | - Zachary T Colburn
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
| | - Jonathan C R Jones
- School of Molecular Biosciences, Washington State University, Pullman, WA, USA
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42
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Sanyasi S, Majhi RK, Kumar S, Mishra M, Ghosh A, Suar M, Satyam PV, Mohapatra H, Goswami C, Goswami L. Polysaccharide-capped silver Nanoparticles inhibit biofilm formation and eliminate multi-drug-resistant bacteria by disrupting bacterial cytoskeleton with reduced cytotoxicity towards mammalian cells. Sci Rep 2016; 6:24929. [PMID: 27125749 PMCID: PMC4850392 DOI: 10.1038/srep24929] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/30/2016] [Indexed: 01/12/2023] Open
Abstract
Development of effective anti-microbial therapeutics has been hindered by the emergence of bacterial strains with multi-drug resistance and biofilm formation capabilities. In this article, we report an efficient green synthesis of silver nanoparticle (AgNP) by in situ reduction and capping with a semi-synthetic polysaccharide-based biopolymer (carboxymethyl tamarind polysaccharide). The CMT-capped AgNPs were characterized by UV, DLS, FE-SEM, EDX and HR-TEM. These AgNPs have average particle size of ~20-40 nm, and show long time stability, indicated by their unchanged SPR and Zeta-potential values. These AgNPs inhibit growth and biofilm formation of both Gram positive (B. subtilis) and Gram negative (E. coli and Salmonella typhimurium) bacterial strains even at concentrations much lower than the minimum inhibitory concentration (MIC) breakpoints of antibiotics, but show reduced or no cytotoxicity against mammalian cells. These AgNPs alter expression and positioning of bacterial cytoskeletal proteins FtsZ and FtsA. CMT-capped AgNPs can effectively block growth of several clinical isolates and MDR strains representing different genera and resistant towards multiple antibiotics belonging to different classes. We propose that the CMT-capped AgNPs can have potential bio-medical application against multi-drug-resistant microbes with minimal cytotoxicity towards mammalian cells.
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Affiliation(s)
- Sridhar Sanyasi
- School of Biotechnology, KIIT University, Patia, Bhubaneswar 751024, India
| | - Rakesh Kumar Majhi
- School of Biological Sciences, National Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya Marg, Bhubaneswar 751005, India
| | - Satish Kumar
- School of Biotechnology, KIIT University, Patia, Bhubaneswar 751024, India
| | - Mitali Mishra
- School of Biological Sciences, National Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya Marg, Bhubaneswar 751005, India
| | - Arnab Ghosh
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Patia, Bhubaneswar 751024, India
| | | | - Harapriya Mohapatra
- School of Biological Sciences, National Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya Marg, Bhubaneswar 751005, India
| | - Chandan Goswami
- School of Biological Sciences, National Institute of Science Education and Research, Institute of Physics Campus, Sachivalaya Marg, Bhubaneswar 751005, India
| | - Luna Goswami
- School of Biotechnology, KIIT University, Patia, Bhubaneswar 751024, India
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43
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Laddomada F, Miyachiro MM, Dessen A. Structural Insights into Protein-Protein Interactions Involved in Bacterial Cell Wall Biogenesis. Antibiotics (Basel) 2016; 5:antibiotics5020014. [PMID: 27136593 PMCID: PMC4929429 DOI: 10.3390/antibiotics5020014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 03/15/2016] [Accepted: 04/09/2016] [Indexed: 12/30/2022] Open
Abstract
The bacterial cell wall is essential for survival, and proteins that participate in its biosynthesis have been the targets of antibiotic development efforts for decades. The biosynthesis of its main component, the peptidoglycan, involves the coordinated action of proteins that are involved in multi-member complexes which are essential for cell division (the “divisome”) and/or cell wall elongation (the “elongasome”), in the case of rod-shaped cells. Our knowledge regarding these interactions has greatly benefitted from the visualization of different aspects of the bacterial cell wall and its cytoskeleton by cryoelectron microscopy and tomography, as well as genetic and biochemical screens that have complemented information from high resolution crystal structures of protein complexes involved in divisome or elongasome formation. This review summarizes structural and functional aspects of protein complexes involved in the cytoplasmic and membrane-related steps of peptidoglycan biosynthesis, with a particular focus on protein-protein interactions whereby disruption could lead to the development of novel antibacterial strategies.
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Affiliation(s)
- Federica Laddomada
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, Grenoble F-38044, France.
- Centre National de la Recherche Scientifique (CNRS), IBS, Grenoble F-38044, France.
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), IBS, Grenoble F-38044, France.
| | - Mayara M Miyachiro
- Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, São Paulo 13083-100, Brazil.
| | - Andréa Dessen
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, Grenoble F-38044, France.
- Centre National de la Recherche Scientifique (CNRS), IBS, Grenoble F-38044, France.
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), IBS, Grenoble F-38044, France.
- Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, São Paulo 13083-100, Brazil.
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44
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Busiek KK, Margolin W. Bacterial actin and tubulin homologs in cell growth and division. Curr Biol 2016; 25:R243-R254. [PMID: 25784047 DOI: 10.1016/j.cub.2015.01.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In contrast to the elaborate cytoskeletal machines harbored by eukaryotic cells, such as mitotic spindles, cytoskeletal structures detectable by typical negative stain electron microscopy are generally absent from bacterial cells. As a result, for decades it was thought that bacteria lacked cytoskeletal machines. Revolutions in genomics and fluorescence microscopy have confirmed the existence not only of smaller-scale cytoskeletal structures in bacteria, but also of widespread functional homologs of eukaryotic cytoskeletal proteins. The presence of actin, tubulin, and intermediate filament homologs in these relatively simple cells suggests that primitive cytoskeletons first arose in bacteria. In bacteria such as Escherichia coli, homologs of tubulin and actin directly interact with each other and are crucial for coordinating cell growth and division. The function and direct interactions between these proteins will be the focus of this review.
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Affiliation(s)
- Kimberly K Busiek
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St., Houston, TX 77030, USA
| | - William Margolin
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St., Houston, TX 77030, USA.
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45
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Deng A, Lin W, Shi N, Wu J, Sun Z, Sun Q, Bai H, Pan Y, Wen T. In vitro assembly of the bacterial actin protein MamK from ' Candidatus Magnetobacterium casensis' in the phylum Nitrospirae. Protein Cell 2016; 7:267-280. [PMID: 26960409 PMCID: PMC4818849 DOI: 10.1007/s13238-016-0253-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 02/07/2016] [Indexed: 10/29/2022] Open
Abstract
Magnetotactic bacteria (MTB), a group of phylogenetically diverse organisms that use their unique intracellular magnetosome organelles to swim along the Earth's magnetic field, play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have revealed that the bacterial actin protein MamK plays essential roles in the linear arrangement of magnetosomes in MTB cells belonging to the Proteobacteria phylum. However, the molecular mechanisms of multiple-magnetosome-chain arrangements in MTB remain largely unknown. Here, we report that the MamK filaments from the uncultivated 'Candidatus Magnetobacterium casensis' (Mcas) within the phylum Nitrospirae polymerized in the presence of ATP alone and were stable without obvious ATP hydrolysis-mediated disassembly. MamK in Mcas can convert NTP to NDP and NDP to NMP, showing the highest preference to ATP. Unlike its Magnetospirillum counterparts, which form a single magnetosome chain, or other bacterial actins such as MreB and ParM, the polymerized MamK from Mcas is independent of metal ions and nucleotides except for ATP, and is assembled into well-ordered filamentous bundles consisted of multiple filaments. Our results suggest a dynamically stable assembly of MamK from the uncultivated Nitrospirae MTB that synthesizes multiple magnetosome chains per cell. These findings further improve the current knowledge of biomineralization and organelle biogenesis in prokaryotic systems.
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Affiliation(s)
- Aihua Deng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wei Lin
- Biogeomagnetism Group, Paleomagnetism and Geochronology Laboratory, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Nana Shi
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jie Wu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhaopeng Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinyun Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hua Bai
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongxin Pan
- Biogeomagnetism Group, Paleomagnetism and Geochronology Laboratory, Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Tingyi Wen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
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46
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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: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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47
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Abstract
Understanding mechanisms of bacterial sacculus growth is challenging due to the time and length scales involved. Enzymes three orders of magnitude smaller than the sacculus somehow coordinate and regulate their processes to double the length of the sacculus while preserving its shape and integrity, all over a period of tens of minutes to hours. Decades of effort using techniques ranging from biochemical analysis to microscopy have produced vast amounts of data on the structural and chemical properties of the cell wall, remodeling enzymes and regulatory proteins. The overall mechanism of cell wall synthesis, however, remains elusive. To approach this problem differently, we have developed a coarse-grained simulation method in which, for the first time to our knowledge, the activities of individual enzymes involved are modeled explicitly. We have already used this method to explore many potential molecular mechanisms governing cell wall synthesis, and anticipate applying the same method to other, related questions of bacterial morphogenesis. In this chapter, we present the details of our method, from coarse-graining the cell wall and modeling enzymatic activities to characterizing shape and visualizing sacculus growth.
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48
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El Andari J, Altegoer F, Bange G, Graumann PL. Bacillus subtilis Bactofilins Are Essential for Flagellar Hook- and Filament Assembly and Dynamically Localize into Structures of Less than 100 nm Diameter underneath the Cell Membrane. PLoS One 2015; 10:e0141546. [PMID: 26517549 PMCID: PMC4627819 DOI: 10.1371/journal.pone.0141546] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/10/2015] [Indexed: 11/19/2022] Open
Abstract
Bactofilins are a widely conserved protein family implicated in cell shape maintenance and in bacterial motility. We show that the bactofilins BacE and BacF from Bacillus subtilis are essential for motility. The proteins are required for the establishment of flagellar hook- and filament structures, but apparently not for the formation of basal bodies. Functional YFP fusions to BacE and to BacF localize as discrete assemblies at the B. subtilis cell membrane, and have a diameter of 60 to 70 nm. BacF assemblies are relatively static, and partially colocalize with flagellar basal bodies, while BacE assemblies are fewer per cell than those of BacF and are highly mobile. Tracking of BacE foci showed that the assemblies arrest at a single point for a few hundred milliseconds, showing that a putative interaction with flagellar structures would be transient and fast. When overexpressed or expressed in a heterologous cell system, bactofilins can form filamentous structures, and also form multimers as purified proteins. Our data reveal a propensity for bactofilins to form filaments, however, in B. subtilis cells, bactofilins assemble into defined size assemblies that show a dynamic localization pattern and play a role in flagellar assembly.
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Affiliation(s)
- Jihad El Andari
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, and Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
- University of Freiburg, Faculty of Biology, Schaenzlestrasse 1, D–79104, Freiburg, Germany
| | - Florian Altegoer
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, and Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
| | - Gert Bange
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, and Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
- * E-mail: (PLG); (GB)
| | - Peter L. Graumann
- SYNMIKRO, LOEWE Center for Synthetic Microbiology, and Department of Chemistry, Philipps Universität Marburg, Marburg, Germany
- * E-mail: (PLG); (GB)
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49
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Jahn N, Brantl S, Strahl H. Against the mainstream: the membrane-associated type I toxin BsrG from Bacillus subtilis interferes with cell envelope biosynthesis without increasing membrane permeability. Mol Microbiol 2015; 98:651-66. [PMID: 26234942 DOI: 10.1111/mmi.13146] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2015] [Indexed: 01/09/2023]
Abstract
Toxin-antitoxin loci, which encode a toxic protein alongside with either RNA or a protein able to counteract the toxicity, are widespread among archaea and bacteria. These loci are implicated in persistence, and as addiction modules to ensure stable inheritance of plasmids and phages. In type I toxin-antitoxin systems, a small RNA acts as an antitoxin, which prevents the synthesis of the toxin. Most type I toxins are small hydrophobic membrane proteins generally assumed to induce pores, or otherwise permeabilise the cytoplasmic membrane and, as a result, induce cell death by energy starvation. Here we show that this mode of action is not a conserved property of type I toxins. The analysis of the cellular toxicity caused by Bacillus subtilis prophage SPβ-encoded toxin BsrG revealed that, surprisingly, it neither dissipates membrane potential nor affects cellular ATP-levels. In contrast, BsrG strongly interferes with the cell envelope biosynthesis, causes membrane invaginations together with delocalisation of the cell wall synthesis machinery and triggers autolysis. Furthermore, efficient inhibition of protein biosynthesis is observed. These findings question the simplistic assumption that small membrane targeting toxins generally act by permeabilising the membrane.
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Affiliation(s)
- Natalie Jahn
- Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät, AG Bakteriengenetik, Philosophenweg 12, Jena, D-07743, Germany
| | - Sabine Brantl
- Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät, AG Bakteriengenetik, Philosophenweg 12, Jena, D-07743, Germany
| | - Henrik Strahl
- Newcastle University, Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
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50
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A Cardiolipin-Deficient Mutant of Rhodobacter sphaeroides Has an Altered Cell Shape and Is Impaired in Biofilm Formation. J Bacteriol 2015; 197:3446-55. [PMID: 26283770 DOI: 10.1128/jb.00420-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/13/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Cell shape has been suggested to play an important role in the regulation of bacterial attachment to surfaces and the formation of communities associated with surfaces. We found that a cardiolipin synthase (Δcls) mutant of the rod-shaped bacterium Rhodobacter sphaeroides--in which synthesis of the anionic, highly curved phospholipid cardiolipin (CL) is reduced by 90%--produces ellipsoid-shaped cells that are impaired in biofilm formation. Reducing the concentration of CL did not cause significant defects in R. sphaeroides cell growth, swimming motility, lipopolysaccharide and exopolysaccharide production, surface adhesion protein expression, and membrane permeability. Complementation of the CL-deficient mutant by ectopically expressing CL synthase restored cells to their rod shape and increased biofilm formation. Treating R. sphaeroides cells with a low concentration (10 μg/ml) of the small-molecule MreB inhibitor S-(3,4-dichlorobenzyl)isothiourea produced ellipsoid-shaped cells that had no obvious growth defect yet reduced R. sphaeroides biofilm formation. This study demonstrates that CL plays a role in R. sphaeroides cell shape determination, biofilm formation, and the ability of the bacterium to adapt to its environment. IMPORTANCE Membrane composition plays a fundamental role in the adaptation of many bacteria to environmental stress. In this study, we build a new connection between the anionic phospholipid cardiolipin (CL) and cellular adaptation in Rhodobacter sphaeroides. We demonstrate that CL plays a role in the regulation of R. sphaeroides morphology and is important for the ability of this bacterium to form biofilms. This study correlates CL concentration, cell shape, and biofilm formation and provides the first example of how membrane composition in bacteria alters cell morphology and influences adaptation. This study also provides insight into the potential of phospholipid biosynthesis as a target for new chemical strategies designed to alter or prevent biofilm formation.
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