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Sidarta M, Lorente Martín AI, Monsalve A, Marinho Righetto G, Schäfer AB, Wenzel M. Lipid phase separation impairs membrane thickness sensing by the Bacillus subtilis sensor kinase DesK. Microbiol Spectr 2024; 12:e0392523. [PMID: 38717171 PMCID: PMC11237406 DOI: 10.1128/spectrum.03925-23] [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: 11/12/2023] [Accepted: 04/08/2024] [Indexed: 06/06/2024] Open
Abstract
Membrane fluidity and thickness have emerged as crucial factors for the activity of and resistance to several antimicrobials. However, the lack of tools to study membrane fluidity and, in particular, thickness in living bacteria limits our understanding of this interplay. The Bacillus subtilis histidine kinase/phosphatase DesK is a molecular sensor that directly detects membrane thickness. It controls activity of DesR, which regulates expression of the lipid desaturase Des, known for its role in cold adaptation and daptomycin susceptibility. We hypothesized that this property could be exploited to develop biosensors and reporters for antibiotic-induced changes in membrane fluidity and thickness. To test this, we designed three assays based on the des system: activation of the Pdes promoter as reporter for membrane thickening, localization of DesK-GFP(green-fluorescent protein) as proxy for rigidified membrane domains, and antibiotic sensitivity of des, desK, and desR deletion mutants as readout for the importance of membrane rigidification/thickening under the tested condition. While we could not confirm the suitability of the des system as reporter for antibiotic-induced changes in membrane thickness, we did observe that des expression is only activated by mild temperature shocks, likely due to partitioning of the sensor DesK into fluid membrane domains upon phase separation, precluding effective thickness sensing under harsh cold shock and antibiotic stress conditions. Similarly, we did not observe any sensitivity of the deletion mutants to either temperature or antibiotic stress, raising the question to what extent the des system contributes to fluidity adaptation under these conditions. IMPORTANCE The B. subtilis des system is a prime model for direct molecular membrane thickness sensor and, as such, has been well studied in vitro. Our study shows that our understanding of its function in vivo and its importance under temperature and antibiotic stress is still very limited. Specifically, our results suggest that (i) the des system senses very subtle membrane fluidity changes that escape detection by established fluidity reporters like laurdan; (ii) membrane thickness sensing by DesK is impaired by phase separation due to partitioning of the protein into the fluid phase; and (iii) fluidity adaptations by Des are too subtle to elicit growth defects under rigidifying conditions, raising the question of how much the des system contributes to adaptation of overall membrane fluidity.
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Affiliation(s)
- Margareth Sidarta
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
| | - Ana I. Lorente Martín
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Anuntxi Monsalve
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Gabriela Marinho Righetto
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
| | - Ann-Britt Schäfer
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
| | - Michaela Wenzel
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
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2
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Howard CB, Rabinovitch A, Yehezkel G, Zaritsky A. Tight coupling of cell width to nucleoid structure in Escherichia coli. Biophys J 2024; 123:502-508. [PMID: 38243596 PMCID: PMC10912912 DOI: 10.1016/j.bpj.2024.01.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 10/24/2023] [Accepted: 01/16/2024] [Indexed: 01/21/2024] Open
Abstract
Cell dimensions of rod-shaped bacteria such as Escherichia coli are connected to mass growth and chromosome replication. During their interdivision cycle (τ min), cells enlarge by elongation only, but at faster growth in richer media, they are also wider. Changes in width W upon nutritional shift-up (shortening τ) occur during the division process. The elusive signal directing the mechanism for W determination is likely related to the tightly linked duplications of the nucleoid (DNA) and the sacculus (peptidoglycan), the only two structures (macromolecules) existing in a single copy that are coupled, temporally and spatially. Six known parameters related to the nucleoid structure and replication are reasonable candidates to convey such a signal, all simple functions of the key number of replication positions n(=C/τ), the ratio between the rates of growth (τ-1) and of replication (C-1). The current analysis of available literature-recorded data discovered that, of these, nucleoid complexity NC[=(2n-1)/(n×ln2)] is by far the most likely parameter affecting cell width W. The exceedingly high correlations found between these two seemingly unrelated measures (NC and W) indicate that coupling between them is of major importance to the species' survival. As an exciting corollary, to the best of our knowledge, a new, indirect approach to estimate DNA replication rate is revealed. Potential involvement of DNA topoisomerases in W determination is also proposed and discussed.
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Affiliation(s)
- Charles B Howard
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Avinoam Rabinovitch
- Department of Physics, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Galit Yehezkel
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel
| | - Arieh Zaritsky
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva, Israel.
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3
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Beyer L, Schäfer AB, Undabarrena A, Mattsby-Baltzer I, Tietze D, Svensson E, Stubelius A, Wenzel M, Cámara B, Tietze AA. Mimicking Nonribosomal Peptides from the Marine Actinomycete Streptomyces sp. H-KF8 Leads to Antimicrobial Peptides. ACS Infect Dis 2024; 10:79-92. [PMID: 38113038 PMCID: PMC10788856 DOI: 10.1021/acsinfecdis.3c00206] [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: 05/03/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/21/2023]
Abstract
Microorganisms within the marine environment have been shown to be very effective sources of naturally produced antimicrobial peptides (AMPs). Several nonribosomal peptides were identified based on genome mining predictions of Streptomyces sp. H-KF8, a marine Actinomycetota isolated from a remote Northern Chilean Patagonian fjord. Based on these predictions, a series of eight peptides, including cyclic peptides, were designed and chemically synthesized. Six of these peptides showed antimicrobial activity. Mode of action studies suggest that two of these peptides potentially act on the cell membrane via a novel mechanism allowing the passage of small ions, resulting in the dissipation of the membrane potential. This study shows that though structurally similar peptides, determined by NMR spectroscopy, the incorporation of small sequence mutations results in a dramatic influence on their bioactivity including mode of action. The qualified hit sequence can serve as a basis for more potent AMPs in future studies.
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Affiliation(s)
- Luisa
I. Beyer
- Department
of Chemistry and Molecular Biology, Wallenberg Centre for Molecular
and Translational Medicine, University of
Gothenburg, Medicinaregatan
7B, Gothenburg 413 90, Sweden
- Center
for Antibiotic Resistance Research in Gothenburg, University of Gothenburg, Box 100, Göteborg 405 30, Sweden
| | - Ann-Britt Schäfer
- Department
of Life Sciences, Chalmers University of
Technology, Kemigården 4, Göteborg 412 96, Sweden
- Center
for Antibiotic Resistance Research in Gothenburg, University of Gothenburg, Box 100, Göteborg 405 30, Sweden
| | - Agustina Undabarrena
- Departamento
de Química & Centro de Biotecnología Daniel Alkalay
Lowitt, Laboratorio de Microbiología Molecular y Biotecnología
Ambiental, Universidad Técnica Federico
Santa María, Valparaíso 2340000, Chile
| | - Inger Mattsby-Baltzer
- Department
of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska
Academy at University of Gothenburg, University
of Gothenburg, Box 440, Göteborg 405 30, Sweden
| | - Daniel Tietze
- Department
of Chemistry and Molecular Biology, Wallenberg Centre for Molecular
and Translational Medicine, University of
Gothenburg, Medicinaregatan
7B, Gothenburg 413 90, Sweden
- Center
for Antibiotic Resistance Research in Gothenburg, University of Gothenburg, Box 100, Göteborg 405 30, Sweden
| | - Elin Svensson
- Department
of Life Sciences, Chalmers University of
Technology, Kemigården 4, Göteborg 412 96, Sweden
| | - Alexandra Stubelius
- Department
of Life Sciences, Chalmers University of
Technology, Kemigården 4, Göteborg 412 96, Sweden
| | - Michaela Wenzel
- Department
of Life Sciences, Chalmers University of
Technology, Kemigården 4, Göteborg 412 96, Sweden
- Center
for Antibiotic Resistance Research in Gothenburg, University of Gothenburg, Box 100, Göteborg 405 30, Sweden
| | - Beatriz Cámara
- Departamento
de Química & Centro de Biotecnología Daniel Alkalay
Lowitt, Laboratorio de Microbiología Molecular y Biotecnología
Ambiental, Universidad Técnica Federico
Santa María, Valparaíso 2340000, Chile
| | - Alesia A. Tietze
- Department
of Chemistry and Molecular Biology, Wallenberg Centre for Molecular
and Translational Medicine, University of
Gothenburg, Medicinaregatan
7B, Gothenburg 413 90, Sweden
- Center
for Antibiotic Resistance Research in Gothenburg, University of Gothenburg, Box 100, Göteborg 405 30, Sweden
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4
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Termination factor Rho mediates transcriptional reprogramming of Bacillus subtilis stationary phase. PLoS Genet 2023; 19:e1010618. [PMID: 36735730 PMCID: PMC9931155 DOI: 10.1371/journal.pgen.1010618] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 02/15/2023] [Accepted: 01/14/2023] [Indexed: 02/04/2023] Open
Abstract
Transcription termination factor Rho is known for its ubiquitous role in suppression of pervasive, mostly antisense, transcription. In the model Gram-positive bacterium Bacillus subtilis, de-repression of pervasive transcription by inactivation of rho revealed the role of Rho in the regulation of post-exponential differentiation programs. To identify other aspects of the regulatory role of Rho during adaptation to starvation, we have constructed a B. subtilis strain (Rho+) that expresses rho at a relatively stable high level in order to compensate for its decrease in the wild-type cells entering stationary phase. The RNAseq analysis of Rho+, WT and Δrho strains (expression profiles can be visualized at http://genoscapist.migale.inrae.fr/seb_rho/) shows that Rho over-production enhances the termination efficiency of Rho-sensitive terminators, thus reducing transcriptional read-through and antisense transcription genome-wide. Moreover, the Rho+ strain exhibits global alterations of sense transcription with the most significant changes observed for the AbrB, CodY, and stringent response regulons, forming the pathways governing the transition to stationary phase. Subsequent physiological analyses demonstrated that maintaining rho expression at a stable elevated level modifies stationary phase-specific physiology of B. subtilis cells, weakens stringent response, and thereby negatively affects the cellular adaptation to nutrient limitations and other stresses, and blocks the development of genetic competence and sporulation. These results highlight the Rho-specific termination of transcription as a novel element controlling stationary phase. The release of this control by decreasing Rho levels during the transition to stationary phase appears crucial for the functionality of complex gene networks ensuring B. subtilis survival in stationary phase.
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5
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Schäfer AB, Steenhuis M, Jim KK, Neef J, O’Keefe S, Whitehead RC, Swanton E, Wang B, Halbedel S, High S, van Dijl JM, Luirink J, Wenzel M. Dual Action of Eeyarestatin 24 on Sec-Dependent Protein Secretion and Bacterial DNA. ACS Infect Dis 2023; 9:253-269. [PMID: 36637435 PMCID: PMC9926488 DOI: 10.1021/acsinfecdis.2c00404] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Eeyarestatin 24 (ES24) is a promising new antibiotic with broad-spectrum activity. It shares structural similarity with nitrofurantoin (NFT), yet appears to have a distinct and novel mechanism: ES24 was found to inhibit SecYEG-mediated protein transport and membrane insertion in Gram-negative bacteria. However, possible additional targets have not yet been explored. Moreover, its activity was notably better against Gram-positive bacteria, for which its mechanism of action had not yet been investigated. We have used transcriptomic stress response profiling, phenotypic assays, and protein secretion analyses to investigate the mode of action of ES24 in comparison with NFT using the Gram-positive model bacterium Bacillus subtilis and have compared our findings to Gram-negative Escherichia coli. Here, we show the inhibition of Sec-dependent protein secretion in B. subtilis and additionally provide evidence for DNA damage, probably caused by the generation of reactive derivatives of ES24. Interestingly, ES24 caused a gradual dissipation of the membrane potential, which led to delocalization of cytokinetic proteins and subsequent cell elongation in E. coli. However, none of those effects were observed in B. subtilis, thereby suggesting that ES24 displays distinct mechanistic differences with respect to Gram-positive and Gram-negative bacteria. Despite its structural similarity to NFT, ES24 profoundly differed in our phenotypic analysis, which implies that it does not share the NFT mechanism of generalized macromolecule and structural damage. Importantly, ES24 outperformed NFT in vivo in a zebrafish embryo pneumococcal infection model. Our results suggest that ES24 not only inhibits the Sec translocon, but also targets bacterial DNA and, in Gram-negative bacteria, the cell membrane.
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Affiliation(s)
- Ann-Britt Schäfer
- Division
of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Maurice Steenhuis
- Molecular
Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Kin Ki Jim
- Department
of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centers - Location Vrije Universiteit
Amsterdam, 1081 HZ Amsterdam, The Netherlands,Amsterdam
Institute for Infection and Immunity, Amsterdam
University Medical Centers, 1081 HZ Amsterdam, The Netherlands
| | - Jolanda Neef
- Department
of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, The Netherlands
| | - Sarah O’Keefe
- School
of
Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Roger C. Whitehead
- School
of Chemistry, Faculty of Science and Engineering, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Eileithyia Swanton
- School
of
Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Biwen Wang
- Bacterial
Cell Biology and Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Sven Halbedel
- FG11
Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, 38855 Wernigerode, Germany,Institute
for Medical Microbiology and Hospital Hygiene, Otto von Guericke University Magdeburg, 39120 Magdeburg, Germany
| | - Stephen High
- School
of
Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Jan Maarten van Dijl
- Department
of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, PO Box 30001, 9700 RB Groningen, The Netherlands
| | - Joen Luirink
- Molecular
Microbiology, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands,
| | - Michaela Wenzel
- Division
of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, 412 96 Gothenburg, Sweden,
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6
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Matos de Opitz CL, Sass P. Microscopy-Based Multiwell Assay to Characterize Disturbed Bacterial Morphogenesis Upon Antibiotic Action. Methods Mol Biol 2023; 2601:171-190. [PMID: 36445584 DOI: 10.1007/978-1-0716-2855-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The urgent need of new antimicrobial agents to combat life-threatening bacterial infections demands the identification and characterization of novel compounds that interfere with new and unprecedented target pathways or structures in multiresistant bacteria. Here, bacterial cell division has emerged as a new and promising target pathway for antibiotic intervention. Compounds, which inhibit division, commonly induce a characteristic filamentation phenotype of rod-shaped bacteria, such as Bacillus subtilis. Hence, this filamentation phenotype can be used to identify and characterize novel compounds that primarily target bacterial cell division. Since novel compounds of both synthetic and natural product origin are often available in small amounts only, thereby limiting the number of assays during mode of action studies, we here describe a semiautomated, microscopy-based approach that requires only small volumes of compounds to allow for the real-time observation of their effects on living bacteria, such as filamentation or cell lysis, in high-throughput 96-well-based formats. We provide a detailed workflow for the initial characterization of multiple compounds at once and further tools for the initial, microscopy-based characterization of their antibacterial mode of action.
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Affiliation(s)
- Cruz L Matos de Opitz
- Interfaculty Institute of Microbiology and Infection Medicine, Microbial Bioactive Compounds, University of Tübingen, Tübingen, Germany
| | - Peter Sass
- Interfaculty Institute of Microbiology and Infection Medicine, Microbial Bioactive Compounds, University of Tübingen, Tübingen, Germany.
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7
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Saaki TNV, Teng Z, Wenzel M, Ventroux M, Carballido-Lόpez R, Noirot-Gros MF, Hamoen LW. SepF supports the recruitment of the DNA translocase SftA to the Z-ring. Mol Microbiol 2022; 117:1263-1274. [PMID: 35411648 PMCID: PMC9320952 DOI: 10.1111/mmi.14906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 04/07/2022] [Accepted: 04/09/2022] [Indexed: 11/28/2022]
Abstract
In many bacteria, cell division begins before the sister chromosomes are fully segregated. Specific DNA translocases ensure that the chromosome is removed from the closing septum, such as the transmembrane protein FtsK in Escherichia coli. Bacillus subtilis contains two FtsK homologues, SpoIIIE and SftA. SftA is active during vegetative growth whereas SpoIIIE is primarily active during sporulation and pumps the chromosome into the spore compartment. FtsK and SpoIIIE contain several transmembrane helices, however SftA is assumed to be a cytoplasmic protein. It is unknown how SftA is recruited to the cell division site. Here we show that SftA is a peripheral membrane protein, containing an N-terminal amphipathic helix that reversibly anchors the protein to the cell membrane. Using a yeast two-hybrid screen we found that SftA interacts with the conserved cell division protein SepF. Based on extensive genetic analyses and previous data we propose that the septal localization of SftA depends on either SepF or the cell division protein FtsA. Since SftA seems to interfere with the activity of SepF, and since inactivation of SepF mitigates the sensitivity of a ∆sftA mutant for ciprofloxacin, we speculate that SftA might delay septum synthesis when chromosomal DNA is in the vicinity.
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Affiliation(s)
- Terrens N V Saaki
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - Zihao Teng
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
| | - Michaela Wenzel
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands.,current address: Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Magali Ventroux
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay Jouy-en-Josas, France
| | - Rut Carballido-Lόpez
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay Jouy-en-Josas, France
| | | | - Leendert W Hamoen
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
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8
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A High-Content Microscopy Screening Identifies New Genes Involved in Cell Width Control in Bacillus subtilis. mSystems 2021; 6:e0101721. [PMID: 34846166 PMCID: PMC8631317 DOI: 10.1128/msystems.01017-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
How cells control their shape and size is a fundamental question of biology. In most bacteria, cell shape is imposed by the peptidoglycan (PG) polymeric meshwork that surrounds the cell. Thus, bacterial cell morphogenesis results from the coordinated action of the proteins assembling and degrading the PG shell. Remarkably, during steady-state growth, most bacteria maintain a defined shape along generations, suggesting that error-proof mechanisms tightly control the process. In the rod-shaped model for the Gram-positive bacterium Bacillus subtilis, the average cell length varies as a function of the growth rate, but the cell diameter remains constant throughout the cell cycle and across growth conditions. Here, in an attempt to shed light on the cellular circuits controlling bacterial cell width, we developed a screen to identify genetic determinants of cell width in B. subtilis. Using high-content screening (HCS) fluorescence microscopy and semiautomated measurement of single-cell dimensions, we screened a library of ∼4,000 single knockout mutants. We identified 13 mutations significantly altering cell diameter, in genes that belong to several functional groups. In particular, our results indicate that metabolism plays a major role in cell width control in B. subtilis. IMPORTANCE Bacterial shape is primarily dictated by the external cell wall, a vital structure that, as such, is the target of countless antibiotics. Our understanding of how bacteria synthesize and maintain this structure is therefore a cardinal question for both basic and applied research. Bacteria usually multiply from generation to generation while maintaining their progenies with rigorously identical shapes. This implies that the bacterial cells constantly monitor and maintain a set of parameters to ensure this perpetuation. Here, our study uses a large-scale microscopy approach to identify at the whole-genome level, in a model bacterium, the genes involved in the control of one of the most tightly controlled cellular parameters, the cell width.
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9
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Different resource allocation in a Bacillus subtilis population displaying bimodal motility. J Bacteriol 2021; 203:e0003721. [PMID: 33782055 DOI: 10.1128/jb.00037-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
To cope with sudden changes in their environment, bacteria can use a bet-hedging strategy by dividing the population into cells with different properties. This so-called bimodal or bistable cellular differentiation is generally controlled by positive feedback regulation of transcriptional activators. Due to the continuous increase in cell volume, it is difficult for these activators to reach an activation threshold concentration when cells are growing exponentially. This is one reason why bimodal differentiation is primarily observed from the onset of the stationary phase when exponential growth ceases. An exception is the bimodal induction of motility in Bacillus subtilis, which occurs early during exponential growth. Several mechanisms have been put forward to explain this, including double negative-feedback regulation and the stability of the mRNA molecules involved. In this study, we used fluorescence-assisted cell sorting to compare the transcriptome of motile and non-motile cells and noted that expression of ribosomal genes is lower in motile cells. This was confirmed using an unstable GFP reporter fused to the strong ribosomal rpsD promoter. We propose that the reduction in ribosomal gene expression in motile cells is the result of a diversion of cellular resources to the synthesis of the chemotaxis and motility systems. In agreement, single-cell microscopic analysis showed that motile cells are slightly shorter than non-motile cells, an indication of slower growth. We speculate that this growth rate reduction can contribute to the bimodal induction of motility during exponential growth.IMPORTANCETo cope with sudden environmental changes, bacteria can use a bet-hedging strategy and generate different types of cells within a population, so called bimodal differentiation. For example, a Bacillus subtilis culture can contain both motile and non-motile cells. In this study we compared the gene expression between motile and non-motile cells. It appeared that motile cells express less ribosomes. To confirm this, we constructed a ribosomal promoter fusion that enabled us to measure expression of this promoter in individual cells. This reporter fusion confirmed our initial finding. The re-allocation of cellular resources from ribosome synthesis towards synthesis of the motility apparatus results in a reduction in growth. Interestingly, this growth reduction has been shown to stimulate bimodal differentiation.
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10
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Morales Angeles D, Macia-Valero A, Bohorquez LC, Scheffers DJ. The PASTA domains of Bacillus subtilis PBP2B strengthen the interaction of PBP2B with DivIB. MICROBIOLOGY (READING, ENGLAND) 2020; 166:826-836. [PMID: 32749956 PMCID: PMC7654742 DOI: 10.1099/mic.0.000957] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/13/2020] [Indexed: 12/15/2022]
Abstract
Bacterial cell division is mediated by a protein complex known as the divisome. Many protein-protein interactions in the divisome have been characterized. In this report, we analyse the role of the PASTA (Penicillin-binding protein And Serine Threonine kinase Associated) domains of Bacillus subtilis PBP2B. PBP2B itself is essential and cannot be deleted, but removing the PBP2B PASTA domains results in impaired cell division and a heat-sensitive phenotype. This resembles the deletion of divIB, a known interaction partner of PBP2B. Bacterial two-hybrid and co-immunoprecipitation analyses show that the interaction between PBP2B and DivIB is weakened when the PBP2B PASTA domains are removed. Combined, our results show that the PBP2B PASTA domains are required to strengthen the interaction between PBP2B and DivIB.
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Affiliation(s)
- Danae Morales Angeles
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Present address: Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Ås, Norway
| | - Alicia Macia-Valero
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Laura C. Bohorquez
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
- Present address: BluSense Diagnostics ApS, Carrera 63 100-49, Bogota 111121, Colombia
| | - Dirk-Jan Scheffers
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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11
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van Raaphorst R, Kjos M, Veening J. BactMAP: An R package for integrating, analyzing and visualizing bacterial microscopy data. Mol Microbiol 2020; 113:297-308. [PMID: 31693257 PMCID: PMC7027861 DOI: 10.1111/mmi.14417] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2019] [Indexed: 12/13/2022]
Abstract
High-throughput analyses of single-cell microscopy data are a critical tool within the field of bacterial cell biology. Several programs have been developed to specifically segment bacterial cells from phase-contrast images. Together with spot and object detection algorithms, these programs offer powerful approaches to quantify observations from microscopy data, ranging from cell-to-cell genealogy to localization and movement of proteins. Most segmentation programs contain specific post-processing and plotting options, but these options vary between programs and possibilities to optimize or alter the outputs are often limited. Therefore, we developed BactMAP (Bacterial toolbox for Microscopy Analysis & Plotting), a command-line based R package that allows researchers to transform cell segmentation and spot detection data generated by different programs into various plots. Furthermore, BactMAP makes it possible to perform custom analyses and change the layout of the output. Because BactMAP works independently of segmentation and detection programs, inputs from different sources can be compared within the same analysis pipeline. BactMAP complies with standard practice in R which enables the use of advanced statistical analysis tools, and its graphic output is compatible with ggplot2, enabling adjustable plot graphics in every operating system. User feedback will be used to create a fully automated Graphical User Interface version of BactMAP in the future. Using BactMAP, we visualize key cell cycle parameters in Bacillus subtilis and Staphylococcus aureus, and demonstrate that the DNA replication forks in Streptococcus pneumoniae dissociate and associate before splitting of the cell, after the Z-ring is formed at the new quarter positions. BactMAP is available from https://veeninglab.com/bactmap.
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Affiliation(s)
- Renske van Raaphorst
- Department of Fundamental MicrobiologyFaculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
- Molecular Genetics GroupGroningen Biomolecular Sciences and Biotechnology InstituteCentre for Synthetic BiologyUniversity of GroningenGroningenThe Netherlands
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food ScienceNorwegian University of Life SciencesÅsNorway
| | - Jan‐Willem Veening
- Department of Fundamental MicrobiologyFaculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
- Molecular Genetics GroupGroningen Biomolecular Sciences and Biotechnology InstituteCentre for Synthetic BiologyUniversity of GroningenGroningenThe Netherlands
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12
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Gao Y, Wenzel M, Jonker MJ, Hamoen LW. Free SepF interferes with recruitment of late cell division proteins. Sci Rep 2017; 7:16928. [PMID: 29209072 PMCID: PMC5717166 DOI: 10.1038/s41598-017-17155-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/16/2017] [Indexed: 12/24/2022] Open
Abstract
The conserved cell division protein SepF aligns polymers of FtsZ, the key cell division protein in bacteria, during synthesis of the (Fts)Z-ring at midcell, the first stage in cytokinesis. In addition, SepF acts as a membrane anchor for the Z-ring. Recently, it was shown that SepF overexpression in Mycobacterium smegmatis blocks cell division. Why this is the case is not known. Surprisingly, we found in Bacillus subtilis that SepF overproduction does not interfere with Z-ring assembly, but instead blocks assembly of late division proteins responsible for septum synthesis. Transposon mutagenesis suggested that SepF overproduction suppresses the essential WalRK two-component system, which stimulates expression of ftsZ. Indeed, it emerged that SepF overproduction impairs normal WalK localization. However, transcriptome analysis showed that the WalRK activity was in fact not reduced in SepF overexpressing cells. Further experiments indicated that SepF competes with EzrA and FtsA for binding to FtsZ, and that binding of extra SepF by FtsZ alleviates the cell division defect. This may explain why activation of WalRK in the transposon mutant, which increases ftsZ expression, counteracts the division defect. In conclusion, our data shows that an imbalance in early cell division proteins can interfere with recruitment of late cell division proteins.
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Affiliation(s)
- Yongqiang Gao
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Michaela Wenzel
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| | - Martijs J Jonker
- MicroArray Department and Integrative Bioinformatics Unit, Swammerdam Institute for Life Sciences, University of Amsterdam, Sciencepark 904, 1098 XH, Amsterdam, The Netherlands
| | - Leendert W Hamoen
- Swammerdam Institute for Life Sciences, University of Amsterdam, O|2 Building, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
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13
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Ursell T, Lee TK, Shiomi D, Shi H, Tropini C, Monds RD, Colavin A, Billings G, Bhaya-Grossman I, Broxton M, Huang BE, Niki H, Huang KC. Rapid, precise quantification of bacterial cellular dimensions across a genomic-scale knockout library. BMC Biol 2017; 15:17. [PMID: 28222723 PMCID: PMC5320674 DOI: 10.1186/s12915-017-0348-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 01/06/2017] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The determination and regulation of cell morphology are critical components of cell-cycle control, fitness, and development in both single-cell and multicellular organisms. Understanding how environmental factors, chemical perturbations, and genetic differences affect cell morphology requires precise, unbiased, and validated measurements of cell-shape features. RESULTS Here we introduce two software packages, Morphometrics and BlurLab, that together enable automated, computationally efficient, unbiased identification of cells and morphological features. We applied these tools to bacterial cells because the small size of these cells and the subtlety of certain morphological changes have thus far obscured correlations between bacterial morphology and genotype. We used an online resource of images of the Keio knockout library of nonessential genes in the Gram-negative bacterium Escherichia coli to demonstrate that cell width, width variability, and length significantly correlate with each other and with drug treatments, nutrient changes, and environmental conditions. Further, we combined morphological classification of genetic variants with genetic meta-analysis to reveal novel connections among gene function, fitness, and cell morphology, thus suggesting potential functions for unknown genes and differences in modes of action of antibiotics. CONCLUSIONS Morphometrics and BlurLab set the stage for future quantitative studies of bacterial cell shape and intracellular localization. The previously unappreciated connections between morphological parameters measured with these software packages and the cellular environment point toward novel mechanistic connections among physiological perturbations, cell fitness, and growth.
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Affiliation(s)
- Tristan Ursell
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.,Department of Physics, University of Oregon, Eugene, OR, 97403, USA
| | - Timothy K Lee
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Daisuke Shiomi
- National Institute of Genetics, Shizuoka, Japan.,Current address: Department of Life Science, Rikkyo University, Tokyo, Japan
| | - Handuo Shi
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Carolina Tropini
- Biophysics Program, Stanford University School of Medicine, Stanford, CA, 94305, USA.,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Russell D Monds
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.,Current address: Synthetic Genomics Inc., La Jolla, CA, 92037, USA
| | - Alexandre Colavin
- Biophysics Program, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Gabriel Billings
- Department of Physics, Stanford University, Stanford, CA, 94305, USA
| | | | - Michael Broxton
- Department of Computer Science, Stanford University, Stanford, CA, 94305, 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.
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14
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Sauer C, Syvertsson S, Bohorquez LC, Cruz R, Harwood CR, van Rij T, Hamoen LW. Effect of Genome Position on Heterologous Gene Expression in Bacillus subtilis: An Unbiased Analysis. ACS Synth Biol 2016; 5:942-7. [PMID: 27197833 DOI: 10.1021/acssynbio.6b00065] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A fixed gene copy number is important for the in silico construction of engineered synthetic networks. However, the copy number of integrated genes depends on their genomic location. This gene dosage effect is rarely addressed in synthetic biology. Two studies in Escherichia coli presented conflicting data on the impact of gene dosage. Here, we investigate how genome location and gene orientation influences expression in Bacillus subtilis. An important difference with the E. coli studies is that we used an unbiased genome integration approach mediated by random transposon insertion. We found that there is a strong gene dosage effect in fast growing B. subtilis cells, which can amount to a 5-fold difference in gene expression. In contrast, gene orientation with respect to DNA replication direction does not influence gene expression. Our study shows that gene dosage should be taken into account when designing synthetic circuits in B. subtilis and presumably other bacteria.
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Affiliation(s)
- Christopher Sauer
- Centre
for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, NE2 4AX Newcastle, United Kingdom
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | - Simon Syvertsson
- Centre
for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, NE2 4AX Newcastle, United Kingdom
| | - Laura C. Bohorquez
- Bacterial
Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, De Boelelaan, 1081 HZ Amsterdam, The Netherlands
| | - Rita Cruz
- Centre
for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, NE2 4AX Newcastle, United Kingdom
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | - Colin R. Harwood
- Centre
for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, NE2 4AX Newcastle, United Kingdom
| | - Tjeerd van Rij
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | - Leendert W. Hamoen
- Centre
for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, NE2 4AX Newcastle, United Kingdom
- Bacterial
Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, De Boelelaan, 1081 HZ Amsterdam, The Netherlands
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