1
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Koo BM, Todor H, Sun J, van Gestel J, Hawkins JS, Hearne CC, Banta AB, Huang KC, Peters JM, Gross CA. Comprehensive double-mutant analysis of the Bacillus subtilis envelope using double-CRISPRi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.14.608006. [PMID: 39185233 PMCID: PMC11343205 DOI: 10.1101/2024.08.14.608006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Understanding bacterial gene function remains a major biological challenge. Double-mutant genetic interaction (GI) analysis addresses this challenge by uncovering the functional partners of targeted genes, allowing us to associate genes of unknown function with novel pathways and unravel connections between well-studied pathways, but is difficult to implement at the genome-scale. Here, we develop and use double-CRISPRi to systematically quantify genetic interactions at scale in the Bacillus subtilis envelope, including essential genes. We discover > 1000 known and novel genetic interactions. Our analysis pipeline and experimental follow-ups reveal the distinct roles of paralogous genes such as the mreB and mbl actin homologs, and identify new genes involved in the well-studied process of cell division. Overall, our study provides valuable insights into gene function and demonstrates the utility of double-CRISPRi for high-throughput dissection of bacterial gene networks, providing a blueprint for future studies in diverse bacterial species.
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2
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Herrera-Jordan K, Pennington P, Zea L. Reduced Pseudomonas aeruginosa Cell Size Observed on Planktonic Cultures Grown in the International Space Station. Microorganisms 2024; 12:393. [PMID: 38399797 PMCID: PMC10892763 DOI: 10.3390/microorganisms12020393] [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: 12/21/2023] [Revised: 02/02/2024] [Accepted: 02/02/2024] [Indexed: 02/25/2024] Open
Abstract
Bacterial growth and behavior have been studied in microgravity in the past, but little focus has been directed to cell size despite its impact on a myriad of processes, including biofilm formation, which is impactful regarding crew health. To interrogate this characteristic, supernatant aliquots of P. aeruginosa cultured on different materials and media on board the International Space Station (ISS) as part of the Space Biofilms Project were analyzed. For that experiment, P. aeruginosa was grown in microgravity-with matching Earth controls-in modified artificial urine medium (mAUMg-high Pi) or LB Lennox supplemented with KNO3, and its formation of biofilms on six different materials was assessed. After one, two, and three days of incubation, the ISS crew terminated subsets of the experiment by fixation in paraformaldehyde, and aliquots of the supernatant were used for the planktonic cell size study presented here. The measurements were obtained post-flight through the use of phase contrast microscopy under oil immersion, a Moticam 10+ digital camera, and the FIJI image analysis program. Statistical comparisons were conducted to identify which treatments caused significant differences in cell dimensions using the Kruskal-Wallis and Dunn tests. There were statistically significant differences as a function of material present in the culture in both LBK and mAUMg-high Pi. Along with this, the data were also grouped by gravitational condition, media, and days of incubation. Comparison of planktonic cells cultured in microgravity showed reduced cell length (from 4% to 10% depending on the material) and diameter (from 1% to 10% depending on the material) with respect to their matching Earth controls, with the caveat that the cultures may have been at different points in their growth curve at a given time. In conclusion, smaller cells were observed on the cultures grown in microgravity, and cell size changed as a function of incubation time and the material upon which the culture grew. We describe these changes here and possible implications for human space travel in terms of crew health and potential applications.
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Affiliation(s)
- Katherinne Herrera-Jordan
- Department of Biochemistry and Microbiology, Universidad del Valle de Guatemala, Guatemala City 01015, Guatemala;
| | - Pamela Pennington
- Research Institute, Universidad del Valle de Guatemala, Guatemala City 01015, Guatemala;
| | - Luis Zea
- Aerospace Engineering Sciences Department, University of Colorado, Boulder, CO 80309, USA
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3
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Keller LJ, Nguyen TH, Liu LJ, Hurysz BM, Lakemeyer M, Guerra M, Gelsinger DJ, Chanin R, Ngo N, Lum KM, Faucher F, Ipock P, Niphakis MJ, Bhatt AS, O'Donoghue AJ, Huang KC, Bogyo M. Chemoproteomic identification of a DPP4 homolog in Bacteroides thetaiotaomicron. Nat Chem Biol 2023; 19:1469-1479. [PMID: 37349583 DOI: 10.1038/s41589-023-01357-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 05/08/2023] [Indexed: 06/24/2023]
Abstract
Serine hydrolases have important roles in signaling and human metabolism, yet little is known about their functions in gut commensal bacteria. Using bioinformatics and chemoproteomics, we identify serine hydrolases in the gut commensal Bacteroides thetaiotaomicron that are specific to the Bacteroidetes phylum. Two are predicted homologs of the human dipeptidyl peptidase 4 (hDPP4), a key enzyme that regulates insulin signaling. Our functional studies reveal that BT4193 is a true homolog of hDPP4 that can be inhibited by FDA-approved type 2 diabetes medications targeting hDPP4, while the other is a misannotated proline-specific triaminopeptidase. We demonstrate that BT4193 is important for envelope integrity and that loss of BT4193 reduces B. thetaiotaomicron fitness during in vitro growth within a diverse community. However, neither function is dependent on BT4193 proteolytic activity, suggesting a scaffolding or signaling function for this bacterial protease.
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Affiliation(s)
- Laura J Keller
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Taylor H Nguyen
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Lawrence J Liu
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Brianna M Hurysz
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Markus Lakemeyer
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University, Jena, Germany
| | - Matteo Guerra
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Biochemical and Cellular Pharmacology, Genentech, San Francisco, CA, USA
| | - Danielle J Gelsinger
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Rachael Chanin
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Divisions of Hematology and Blood and Marrow Transplantation, Department of Medicine, Stanford University, Stanford, CA, USA
| | - Nhi Ngo
- Lundbeck La Jolla Research Center, Inc., San Diego, CA, USA
| | - Kenneth M Lum
- Lundbeck La Jolla Research Center, Inc., San Diego, CA, USA
| | - Franco Faucher
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Phillip Ipock
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Ami S Bhatt
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
- Divisions of Hematology and Blood and Marrow Transplantation, Department of Medicine, Stanford University, Stanford, CA, USA
| | - Anthony J O'Donoghue
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Matthew Bogyo
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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4
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Rueff AS, van Raaphorst R, Aggarwal SD, Santos-Moreno J, Laloux G, Schaerli Y, Weiser JN, Veening JW. Synthetic genetic oscillators demonstrate the functional importance of phenotypic variation in pneumococcal-host interactions. Nat Commun 2023; 14:7454. [PMID: 37978173 PMCID: PMC10656556 DOI: 10.1038/s41467-023-43241-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023] Open
Abstract
Phenotypic variation is the phenomenon in which clonal cells display different traits even under identical environmental conditions. This plasticity is thought to be important for processes including bacterial virulence, but direct evidence for its relevance is often lacking. For instance, variation in capsule production in the human pathogen Streptococcus pneumoniae has been linked to different clinical outcomes, but the exact relationship between variation and pathogenesis is not well understood due to complex natural regulation. In this study, we use synthetic oscillatory gene regulatory networks (GRNs) based on CRISPR interference (CRISPRi) together with live cell imaging and cell tracking within microfluidics devices to mimic and test the biological function of bacterial phenotypic variation. We provide a universally applicable approach for engineering intricate GRNs using only two components: dCas9 and extended sgRNAs (ext-sgRNAs). Our findings demonstrate that variation in capsule production is beneficial for pneumococcal fitness in traits associated with pathogenesis providing conclusive evidence for this longstanding question.
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Affiliation(s)
- Anne-Stéphanie Rueff
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
| | - Renske van Raaphorst
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
- de Duve Institute, UCLouvain, 75 Avenue Hippocrate, 1200, Brussels, Belgium
| | - Surya D Aggarwal
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Javier Santos-Moreno
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
- Pompeu Fabra University, Barcelona, Spain
| | - Géraldine Laloux
- de Duve Institute, UCLouvain, 75 Avenue Hippocrate, 1200, Brussels, Belgium
| | - Yolanda Schaerli
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland
| | - Jeffrey N Weiser
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Jan-Willem Veening
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA.
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5
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Wilson SA, Tank RKJ, Hobbs JK, Foster SJ, Garner EC. An exhaustive multiple knockout approach to understanding cell wall hydrolase function in Bacillus subtilis. mBio 2023; 14:e0176023. [PMID: 37768080 PMCID: PMC10653849 DOI: 10.1128/mbio.01760-23] [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: 07/12/2023] [Accepted: 08/03/2023] [Indexed: 09/29/2023] Open
Abstract
IMPORTANCE In order to grow, bacterial cells must both create and break down their cell wall. The enzymes that are responsible for these processes are the target of some of our best antibiotics. Our understanding of the proteins that break down the wall- cell wall hydrolases-has been limited by redundancy among the large number of hydrolases many bacteria contain. To solve this problem, we identified 42 cell wall hydrolases in Bacillus subtilis and created a strain lacking 40 of them. We show that cells can survive using only a single cell wall hydrolase; this means that to understand the growth of B. subtilis in standard laboratory conditions, it is only necessary to study a very limited number of proteins, simplifying the problem substantially. We additionally show that the ∆40 strain is a research tool to characterize hydrolases, using it to identify three "helper" hydrolases that act in certain stress conditions.
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Affiliation(s)
- Sean A. Wilson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
- Center for Systems Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Raveen K. J. Tank
- Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom
| | - Jamie K. Hobbs
- Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom
| | - Simon J. Foster
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
| | - Ethan C. Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
- Center for Systems Biology, Harvard University, Cambridge, Massachusetts, USA
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6
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Mikheyeva IV, Sun J, Huang KC, Silhavy TJ. Mechanism of outer membrane destabilization by global reduction of protein content. Nat Commun 2023; 14:5715. [PMID: 37714857 PMCID: PMC10504340 DOI: 10.1038/s41467-023-40396-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 07/26/2023] [Indexed: 09/17/2023] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria such as Escherichia coli is an asymmetric bilayer with the glycolipid lipopolysaccharide (LPS) in the outer leaflet and glycerophospholipids in the inner. Nearly all integral OM proteins (OMPs) have a characteristic β-barrel fold and are assembled in the OM by the BAM complex, which contains one essential β-barrel protein (BamA), one essential lipoprotein (BamD), and three non-essential lipoproteins (BamBCE). A gain-of-function mutation in bamA enables survival in the absence of BamD, showing that the essential function of this protein is regulatory. Here, we demonstrate that the global reduction in OMPs caused by BamD loss weakens the OM, altering cell shape and causing OM rupture in spent medium. To fill the void created by OMP loss, phospholipids (PLs) flip into the outer leaflet. Under these conditions, mechanisms that remove PLs from the outer leaflet create tension between the OM leaflets, which contributes to membrane rupture. Rupture is prevented by suppressor mutations that release the tension by halting PL removal from the outer leaflet. However, these suppressors do not restore OM stiffness or normal cell shape, revealing a possible connection between OM stiffness and cell shape.
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Affiliation(s)
- Irina V Mikheyeva
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08540, USA
| | - Jiawei Sun
- Department of Bioengineering, 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.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
| | - Thomas J Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ, 08540, USA.
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7
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Knapp BD, Willis L, Gonzalez C, Vashistha H, Touma JJ, Tikhonov M, Ram J, Salman H, Elias JE, Huang KC. Metabolomic rearrangement controls the intrinsic microbial response to temperature changes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.22.550177. [PMID: 37546722 PMCID: PMC10401945 DOI: 10.1101/2023.07.22.550177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Temperature is one of the key determinants of microbial behavior and survival, whose impact is typically studied under heat- or cold-shock conditions that elicit specific regulation to combat lethal stress. At intermediate temperatures, cellular growth rate varies according to the Arrhenius law of thermodynamics without stress responses, a behavior whose origins have not yet been elucidated. Using single-cell microscopy during temperature perturbations, we show that bacteria exhibit a highly conserved, gradual response to temperature upshifts with a time scale of ~1.5 doublings at the higher temperature, regardless of initial/final temperature or nutrient source. We find that this behavior is coupled to a temperature memory, which we rule out as being neither transcriptional, translational, nor membrane dependent. Instead, we demonstrate that an autocatalytic enzyme network incorporating temperature-sensitive Michaelis-Menten kinetics recapitulates all temperature-shift dynamics through metabolome rearrangement, which encodes a temperature memory and successfully predicts alterations in the upshift response observed under simple-sugar, low-nutrient conditions, and in fungi. This model also provides a mechanistic framework for both Arrhenius-dependent growth and the classical Monod Equation through temperature-dependent metabolite flux.
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Affiliation(s)
| | - Lisa Willis
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Carlos Gonzalez
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Harsh Vashistha
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Joanna Jammal Touma
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mikhail Tikhonov
- Department of Physics, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jeffrey Ram
- Department of Physiology, Wayne State University, Detroit, MI 48201, USA
| | - Hanna Salman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Josh E. Elias
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Kerwyn Casey Huang
- Biophysics Program, Stanford University, Stanford, CA 94305, USA
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
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8
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Shiver AL, Sun J, Culver R, Violette A, Wynter C, Nieckarz M, Mattiello SP, Sekhon PK, Friess L, Carlson HK, Wong D, Higginbottom S, Weglarz M, Wang W, Knapp BD, Guiberson E, Sanchez J, Huang PH, Garcia PA, Buie CR, Good B, DeFelice B, Cava F, Scaria J, Sonnenburg J, Sinderen DV, Deutschbauer AM, Huang KC. A mutant fitness compendium in Bifidobacteria reveals molecular determinants of colonization and host-microbe interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555234. [PMID: 37693407 PMCID: PMC10491234 DOI: 10.1101/2023.08.29.555234] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Bifidobacteria commonly represent a dominant constituent of human gut microbiomes during infancy, influencing nutrition, immune development, and resistance to infection. Despite interest as a probiotic therapy, predicting the nutritional requirements and health-promoting effects of Bifidobacteria is challenging due to major knowledge gaps. To overcome these deficiencies, we used large-scale genetics to create a compendium of mutant fitness in Bifidobacterium breve (Bb). We generated a high density, randomly barcoded transposon insertion pool in Bb, and used this pool to determine Bb fitness requirements during colonization of germ-free mice and chickens with multiple diets and in response to hundreds of in vitro perturbations. To enable mechanistic investigation, we constructed an ordered collection of insertion strains covering 1462 genes. We leveraged these tools to improve models of metabolic pathways, reveal unexpected host- and diet-specific requirements for colonization, and connect the production of immunomodulatory molecules to growth benefits. These resources will greatly reduce the barrier to future investigations of this important beneficial microbe.
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Affiliation(s)
- Anthony L. Shiver
- Department of Bioengineering, Stanford University, Stanford CA 94305, USA
| | - Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford CA 94305, USA
| | - Rebecca Culver
- Department of Genetics, Stanford University, Stanford CA 94305, USA
| | - Arvie Violette
- Department of Bioengineering, Stanford University, Stanford CA 94305, USA
| | - Charles Wynter
- Department of Bioengineering, Stanford University, Stanford CA 94305, USA
| | - Marta Nieckarz
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, SE-90187, Sweden
| | - Samara Paula Mattiello
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- College of Mathematics and Science, The University of Tennessee Southern, Pulaski TN 38478, USA
| | - Prabhjot Kaur Sekhon
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, 74074, USA
| | - Lisa Friess
- School of Microbiology, University College Cork, Ireland
- APC Microbiome Ireland, University College Cork, Ireland
| | - Hans K. Carlson
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Daniel Wong
- Department of Applied Physics, Stanford University, Stanford CA 94305, USA
| | - Steven Higginbottom
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Meredith Weglarz
- Stanford Shared FACS Facility, Center for Molecular and Genetic Medicine, Stanford University, Stanford, California, USA
| | - Weigao Wang
- Department of Chemical Engineering, Stanford University, Stanford CA 94305, USA
| | | | - Emma Guiberson
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Po-Hsun Huang
- Department of Mechanical Engineering, Laboratory for Energy and Microsystems Innovation, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139, MA, USA
| | - Paulo A. Garcia
- Department of Mechanical Engineering, Laboratory for Energy and Microsystems Innovation, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139, MA, USA
| | - Cullen R. Buie
- Department of Mechanical Engineering, Laboratory for Energy and Microsystems Innovation, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139, MA, USA
| | - Benjamin Good
- Department of Applied Physics, Stanford University, Stanford CA 94305, USA
| | | | - Felipe Cava
- Department of Molecular Biology and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, SE-90187, Sweden
| | - Joy Scaria
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK, 74074, USA
| | - Justin Sonnenburg
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Douwe Van Sinderen
- School of Microbiology, University College Cork, Ireland
- APC Microbiome Ireland, University College Cork, Ireland
| | - Adam M. Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, 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, USA
- Chan-Zuckerberg Biohub, San Francisco, CA 94158
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9
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Rueff AS, van Raaphorst R, Aggarwal S, Santos-Moreno J, Laloux G, Schaerli Y, Weiser JN, Veening JW. Rewiring capsule production by CRISPRi-based genetic oscillators demonstrates a functional role of phenotypic variation in pneumococcal-host interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.03.543575. [PMID: 37398107 PMCID: PMC10312626 DOI: 10.1101/2023.06.03.543575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Phenotypic variation is the phenomenon in which clonal cells display different traits even under identical environmental conditions. This plasticity is thought to be important for processes including bacterial virulence1-8, but direct evidence for its relevance is often lacking. For instance, variation in capsule production in the human pathogen Streptococcus pneumoniae has been linked to different clinical outcomes9-14, but the exact relationship between variation and pathogenesis is not well understood due to complex natural regulation15-20. In this study, we used synthetic oscillatory gene regulatory networks (GRNs) based on CRISPR interference together with live cell microscopy and cell tracking within microfluidics devices to mimic and test the biological function of bacterial phenotypic variation. We provide a universally applicable approach for engineering intricate GRNs using only two components: dCas9 and extended sgRNAs (ext-sgRNAs). Our findings demonstrate that variation in capsule production is beneficial for pneumococcal fitness in traits associated with pathogenesis providing conclusive evidence for this longstanding question.
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Affiliation(s)
- Anne-Stéphanie Rueff
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Renske van Raaphorst
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
- de Duve Institute, UCLouvain, 75 Avenue Hippocrate, 1200 Brussels, Belgium
| | - Surya Aggarwal
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Javier Santos-Moreno
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
- Present address: Pompeu Fabra University, Barcelona, Spain
| | - Géraldine Laloux
- de Duve Institute, UCLouvain, 75 Avenue Hippocrate, 1200 Brussels, Belgium
| | - Yolanda Schaerli
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Jeffrey N. Weiser
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Jan-Willem Veening
- Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
- Department of Pediatrics, University of California San Diego, La Jolla, California, USA
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
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10
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Mikheyeva IV, Sun J, Huang KC, Silhavy TJ. Mechanism of outer membrane destabilization by global reduction of protein content. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.19.529137. [PMID: 36865163 PMCID: PMC9980000 DOI: 10.1101/2023.02.19.529137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The outer membrane (OM) of Gram-negative bacteria such as Escherichia coli is an asymmetric bilayer with the glycolipid lipopolysaccharide (LPS) in the outer leaflet and glycerophospholipids in the inner. Nearly all integral OM proteins (OMPs) have a characteristic β-barrel fold and are assembled in the OM by the BAM complex, which contains one essential β-barrel protein (BamA), one essential lipoprotein (BamD), and three non-essential lipoproteins (BamBCE). A gain-of-function mutation in bamA enables survival in the absence of BamD, showing that the essential function of this protein is regulatory. We demonstrate that the global reduction in OMPs caused by BamD loss weakens the OM, altering cell shape and causing OM rupture in spent medium. To fill the void created by OMP loss, PLs flip into the outer leaflet. Under these conditions, mechanisms that remove PLs from the outer leaflet create tension between the OM leaflets, which contributes to membrane rupture. Rupture is prevented by suppressor mutations that release the tension by halting PL removal from the outer leaflet. However, these suppressors do not restore OM stiffness or normal cell shape, revealing a possible connection between OM stiffness and cell shape. Significance Statement The outer membrane (OM) is a selective permeability barrier that contributes to the intrinsic antibiotic resistance of Gram-negative bacteria. Biophysical characterization of the roles of the component proteins, lipopolysaccharides, and phospholipids is limited by both the essentiality of the OM and its asymmetrical organization. In this study, we dramatically change OM physiology by limiting the protein content, which requires phospholipid localization to the outer leaflet and thus disrupts OM asymmetry. By characterizing the perturbed OM of various mutants, we provide novel insight into the links among OM composition, OM stiffness, and cell shape regulation. These findings deepen our understanding of bacterial cell envelope biology and provide a platform for further interrogation of OM properties.
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Affiliation(s)
- Irina V. Mikheyeva
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Jiawei Sun
- Department of Bioengineering, 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
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Thomas J. Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
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11
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High-Resolution Bacterial Cytological Profiling Reveals Intrapopulation Morphological Variations upon Antibiotic Exposure. Antimicrob Agents Chemother 2023; 67:e0130722. [PMID: 36625642 PMCID: PMC9933734 DOI: 10.1128/aac.01307-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Phenotypic heterogeneity is crucial to bacterial survival and could provide insights into the mechanism of action (MOA) of antibiotics, especially those with polypharmacological actions. Although phenotypic changes among individual cells could be detected by existing profiling methods, due to the data complexity, only population average data were commonly used, thereby overlooking the heterogeneity. In this study, we developed a high-resolution bacterial cytological profiling method that can capture morphological variations of bacteria upon antibiotic treatment. With an unprecedented single-cell resolution, this method classifies morphological changes of individual cells into known MOAs with an overall accuracy above 90%. We next showed that combinations of two antibiotics induce altered cell morphologies that are either unique or similar to that of an antibiotic in the combinations. With these combinatorial profiles, this method successfully revealed multiple cytological changes caused by a natural product-derived compound that, by itself, is inactive against Acinetobacter baumannii but synergistically exerts its multiple antibacterial activities in the presence of colistin. The findings have paved the way for future single-cell profiling in bacteria and have highlighted previously underappreciated intrapopulation variations caused by antibiotic perturbation.
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12
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Brajtenbach D, Puls JS, Matos de Opitz CL, Sass P, Kubitscheck U, Grein F. Quantitative Analysis of Microscopy Data to Evaluate Bacterial Responses to Antibiotic Treatment. Methods Mol Biol 2023; 2601:231-257. [PMID: 36445587 DOI: 10.1007/978-1-0716-2855-3_12] [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
Microscopy is a powerful method to evaluate the direct effects of antibiotic action on the single cell level. As with other methodologies, microscopy data is obtained through sufficient biological and technical replicate experiments, where evaluation of the sample is generally followed over time. Even if a single antibiotic is tested for a defined time, the most certain outcome is large amounts of raw data that requires systematic analysis. Although microscopy is a helpful qualitative method, the recorded information is stored as defined quantifiable units, the pixels. When this information is transferred to diverse bioinformatic tools, it is possible to analyze the microscopy data while avoiding the inherent bias associated to manual quantification. Here, we briefly describe methods for the analysis of microscopy images using open-source programs, with a special focus on bacteria exposed to antibiotics.
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Affiliation(s)
- Dominik Brajtenbach
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Jan-Samuel Puls
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - 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.
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany.
| | - Fabian Grein
- Institute for Pharmaceutical Microbiology, University Hospital Bonn, University of Bonn, Bonn, Germany.
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.
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13
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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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14
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Arjes HA, Sun J, Liu H, Nguyen TH, Culver RN, Celis AI, Walton SJ, Vasquez KS, Yu FB, Xue KS, Newton D, Zermeno R, Weglarz M, Deutschbauer A, Huang KC, Shiver AL. Construction and characterization of a genome-scale ordered mutant collection of Bacteroides thetaiotaomicron. BMC Biol 2022; 20:285. [PMID: 36527020 PMCID: PMC9758874 DOI: 10.1186/s12915-022-01481-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 11/24/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Ordered transposon-insertion collections, in which specific transposon-insertion mutants are stored as monocultures in a genome-scale collection, represent a promising tool for genetic dissection of human gut microbiota members. However, publicly available collections are scarce and the construction methodology remains in early stages of development. RESULTS Here, we describe the assembly of a genome-scale ordered collection of transposon-insertion mutants in the model gut anaerobe Bacteroides thetaiotaomicron VPI-5482 that we created as a resource for the research community. We used flow cytometry to sort single cells from a pooled library, located mutants within this initial progenitor collection by applying a pooling strategy with barcode sequencing, and re-arrayed specific mutants to create a condensed collection with single-insertion strains covering >2500 genes. To demonstrate the potential of the condensed collection for phenotypic screening, we analyzed growth dynamics and cell morphology. We identified both growth defects and altered cell shape in mutants disrupting sphingolipid synthesis and thiamine scavenging. Finally, we analyzed the process of assembling the B. theta condensed collection to identify inefficiencies that limited coverage. We demonstrate as part of this analysis that the process of assembling an ordered collection can be accurately modeled using barcode sequencing data. CONCLUSION We expect that utilization of this ordered collection will accelerate research into B. theta physiology and that lessons learned while assembling the collection will inform future efforts to assemble ordered mutant collections for an increasing number of gut microbiota members.
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Affiliation(s)
- Heidi A Arjes
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Hualan Liu
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Taylor H Nguyen
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Rebecca N Culver
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Arianna I Celis
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Sophie Jean Walton
- Biophysics Training Program, Stanford University School of Medicine, Stanford, CA, USA
| | - Kimberly S Vasquez
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | | | - Katherine S Xue
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Daniel Newton
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Ricardo Zermeno
- Stanford Shared FACS Facility, Center for Molecular and Genetic Medicine, Stanford University, Stanford, CA, USA
| | - Meredith Weglarz
- Stanford Shared FACS Facility, Center for Molecular and Genetic Medicine, Stanford University, Stanford, CA, USA
| | - Adam Deutschbauer
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
- Biophysics Training Program, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
| | - Anthony L Shiver
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
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15
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Cesar S, Sun J, Huang KC. Cellular memory of rapid growth is sensitive to nutrient depletion during starvation. Front Microbiol 2022; 13:1016371. [DOI: 10.3389/fmicb.2022.1016371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 11/01/2022] [Indexed: 11/22/2022] Open
Abstract
Bacteria frequently encounter nutrient fluctuations in natural environments, yet we understand little about their ability to maintain physiological memory of previous food sources. Starvation is a particularly acute case, in which cells must balance adaptation to stresses with limited nutrient supply. Here, we show that Escherichia coli cells immediately accelerate and decelerate in growth upon transitions from spent to fresh media and vice versa, respectively, and memory of rapid growth can be maintained for many hours under constant flow of spent medium. However, after transient exposure of stationary-phase cells to fresh medium, subsequent aerobic incubation in increasingly spent medium led to lysis and limited growth when rejuvenated in fresh medium. Growth defects were avoided by incubation in anaerobic spent medium or water, suggesting that defects were caused by respiration during the process of nutrient depletion in spent medium. These findings highlight the importance of respiration for stationary phase survival and underscore the broad range of starvation outcomes depending on environmental history.
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16
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Cutler KJ, Stringer C, Lo TW, Rappez L, Stroustrup N, Brook Peterson S, Wiggins PA, Mougous JD. Omnipose: a high-precision morphology-independent solution for bacterial cell segmentation. Nat Methods 2022; 19:1438-1448. [PMID: 36253643 PMCID: PMC9636021 DOI: 10.1038/s41592-022-01639-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 09/06/2022] [Indexed: 12/26/2022]
Abstract
Advances in microscopy hold great promise for allowing quantitative and precise measurement of morphological and molecular phenomena at the single-cell level in bacteria; however, the potential of this approach is ultimately limited by the availability of methods to faithfully segment cells independent of their morphological or optical characteristics. Here, we present Omnipose, a deep neural network image-segmentation algorithm. Unique network outputs such as the gradient of the distance field allow Omnipose to accurately segment cells on which current algorithms, including its predecessor, Cellpose, produce errors. We show that Omnipose achieves unprecedented segmentation performance on mixed bacterial cultures, antibiotic-treated cells and cells of elongated or branched morphology. Furthermore, the benefits of Omnipose extend to non-bacterial subjects, varied imaging modalities and three-dimensional objects. Finally, we demonstrate the utility of Omnipose in the characterization of extreme morphological phenotypes that arise during interbacterial antagonism. Our results distinguish Omnipose as a powerful tool for characterizing diverse and arbitrarily shaped cell types from imaging data.
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Affiliation(s)
- Kevin J Cutler
- Department of Physics, University of Washington, Seattle, WA, USA
| | | | - Teresa W Lo
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Luca Rappez
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Nicholas Stroustrup
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - S Brook Peterson
- Department of Microbiology, University of Washington, Seattle, WA, USA
| | - Paul A Wiggins
- Department of Physics, University of Washington, Seattle, WA, USA.
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
| | - Joseph D Mougous
- Department of Microbiology, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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17
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Sloan R, Surber J, Roy EJ, Hartig E, Morgenstein RM. Enzyme 1 of the phosphoenolpyruvate:sugar phosphotransferase system is involved in resistance to MreB disruption in wild-type and ∆envC cells. Mol Microbiol 2022; 118:588-600. [PMID: 36199205 PMCID: PMC9671846 DOI: 10.1111/mmi.14988] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/27/2022] [Accepted: 09/30/2022] [Indexed: 01/12/2023]
Abstract
Cell wall synthesis in bacteria is determined by two protein complexes: the elongasome and divisome. The elongasome is coordinated by the actin homolog MreB while the divisome is organized by the tubulin homolog FtsZ. While these two systems must coordinate with each other to ensure that elongation and division are coregulated, this cross talk has been understudied. Using the MreB depolymerizing agent, A22, we found that multiple gene deletions result in cells exhibiting increased sensitivity to MreB depolymerization. One of those genes encodes for EnvC, a part of the divisome that is responsible for splitting daughter cells after the completion of cytokinesis through the activation of specific amidases. Here we show this increased sensitivity to A22 works through two known amidase targets of EnvC: AmiA and AmiB. In addition, suppressor analysis revealed that mutations in enzyme 1 of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) can suppress the effects of A22 in both wild-type and envC deletion cells. Together this work helps to link elongation, division, and metabolism.
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Affiliation(s)
- Ryan Sloan
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Jacob Surber
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Emma J. Roy
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Ethan Hartig
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
| | - Randy M. Morgenstein
- Department of Microbiology and Molecular GeneticsOklahoma State UniversityStillwaterOklahomaUSA
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18
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Navarro PP, Vettiger A, Ananda VY, Llopis PM, Allolio C, Bernhardt TG, Chao LH. Cell wall synthesis and remodelling dynamics determine division site architecture and cell shape in Escherichia coli. Nat Microbiol 2022; 7:1621-1634. [PMID: 36097171 PMCID: PMC9519445 DOI: 10.1038/s41564-022-01210-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 07/21/2022] [Indexed: 01/19/2023]
Abstract
The bacterial division apparatus catalyses the synthesis and remodelling of septal peptidoglycan (sPG) to build the cell wall layer that fortifies the daughter cell poles. Understanding of this essential process has been limited by the lack of native three-dimensional views of developing septa. Here, we apply state-of-the-art cryogenic electron tomography (cryo-ET) and fluorescence microscopy to visualize the division site architecture and sPG biogenesis dynamics of the Gram-negative bacterium Escherichia coli. We identify a wedge-like sPG structure that fortifies the ingrowing septum. Experiments with strains defective in sPG biogenesis revealed that the septal architecture and mode of division can be modified to more closely resemble that of other Gram-negative (Caulobacter crescentus) or Gram-positive (Staphylococcus aureus) bacteria, suggesting that a conserved mechanism underlies the formation of different septal morphologies. Finally, analysis of mutants impaired in amidase activation (ΔenvC ΔnlpD) showed that cell wall remodelling affects the placement and stability of the cytokinetic ring. Taken together, our results support a model in which competition between the cell elongation and division machineries determines the shape of cell constrictions and the poles they form. They also highlight how the activity of the division system can be modulated to help generate the diverse array of shapes observed in the bacterial domain.
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Affiliation(s)
- Paula P Navarro
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Andrea Vettiger
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Virly Y Ananda
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA
| | | | - Christoph Allolio
- Faculty of Mathematics and Physics, Mathematical Institute, Charles University, Prague, Czech Republic
| | - Thomas G Bernhardt
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| | - Luke H Chao
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. .,Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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19
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Kitahara Y, Oldewurtel ER, Wilson S, Sun Y, Altabe S, de Mendoza D, Garner EC, van Teeffelen S. The role of cell-envelope synthesis for envelope growth and cytoplasmic density in Bacillus subtilis. PNAS NEXUS 2022; 1:pgac134. [PMID: 36082236 PMCID: PMC9437589 DOI: 10.1093/pnasnexus/pgac134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 07/21/2022] [Indexed: 01/29/2023]
Abstract
All cells must increase their volumes in response to biomass growth to maintain intracellular mass density within physiologically permissive bounds. Here, we investigate the regulation of volume growth in the Gram-positive bacterium Bacillus subtilis. To increase volume, bacteria enzymatically expand their cell envelopes and insert new envelope material. First, we demonstrate that cell-volume growth is determined indirectly, by expanding their envelopes in proportion to mass growth, similarly to the Gram-negative Escherichia coli, despite their fundamentally different envelope structures. Next, we studied, which pathways might be responsible for robust surface-to-mass coupling: We found that both peptidoglycan synthesis and membrane synthesis are required for proper surface-to-mass coupling. However, surprisingly, neither pathway is solely rate-limiting, contrary to wide-spread belief, since envelope growth continues at a reduced rate upon complete inhibition of either process. To arrest cell-envelope growth completely, the simultaneous inhibition of both envelope-synthesis processes is required. Thus, we suggest that multiple envelope-synthesis pathways collectively confer an important aspect of volume regulation, the coordination between surface growth, and biomass growth.
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Affiliation(s)
- Yuki Kitahara
- Département de Microbiologie, Infectiologie, et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada,Université de Paris, Paris, France,Microbial Morphogenesis and Growth Lab, Institut Pasteur, Paris, France
| | - Enno R Oldewurtel
- Microbial Morphogenesis and Growth Lab, Institut Pasteur, Paris, France
| | - Sean Wilson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, USA,Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | - Yingjie Sun
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, USA,Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | - Silvia Altabe
- Instituto de Biología Molecular y Celular de Rosario (IBR)-Conicet- and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Diego de Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR)-Conicet- and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, USA,Center for Systems Biology, Harvard University, Cambridge, MA, USA
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20
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Cesar S, Willis L, Huang KC. Bacterial respiration during stationary phase induces intracellular damage that leads to delayed regrowth. iScience 2022; 25:103765. [PMID: 35243217 PMCID: PMC8858994 DOI: 10.1016/j.isci.2022.103765] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 04/23/2021] [Accepted: 01/11/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Spencer Cesar
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lisa Willis
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Kerwyn Casey Huang
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
- Corresponding author
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21
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Cell density-dependent antibiotic tolerance to inhibition of the elongation machinery requires fully functional PBP1B. Commun Biol 2022; 5:107. [PMID: 35115684 PMCID: PMC8813938 DOI: 10.1038/s42003-022-03056-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 01/18/2022] [Indexed: 01/20/2023] Open
Abstract
The peptidoglycan (PG) cell wall provides shape and structure to most bacteria. There are two systems to build PG in rod shaped organisms: the elongasome and divisome, which are made up of many proteins including the essential MreB and PBP2, or FtsZ and PBP3, respectively. The elongasome is responsible for PG insertion during cell elongation, while the divisome is responsible for septal PG insertion during division. We found that the main elongasome proteins, MreB and PBP2, can be inhibited without affecting growth rate in a quorum sensing-independent density-dependent manner. Before cells reach a particular cell density, inhibition of the elongasome results in different physiological responses, including intracellular vesicle formation and an increase in cell size. This inhibition of MreB or PBP2 can be compensated for by the presence of the class A penicillin binding protein, PBP1B. Furthermore, we found this density-dependent growth resistance to be specific for elongasome inhibition and was consistent across multiple Gram-negative rods, providing new areas of research into antibiotic treatment.
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22
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Czerwińska-Główka D, Krukiewicz K. Guidelines for a Morphometric Analysis of Prokaryotic and Eukaryotic Cells by Scanning Electron Microscopy. Cells 2021; 10:3304. [PMID: 34943812 PMCID: PMC8699492 DOI: 10.3390/cells10123304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/11/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
The invention of a scanning electron microscopy (SEM) pushed the imaging methods and allowed for the observation of cell details with a high resolution. Currently, SEM appears as an extremely useful tool to analyse the morphology of biological samples. The aim of this paper is to provide a set of guidelines for using SEM to analyse morphology of prokaryotic and eukaryotic cells, taking as model cases Escherichia coli bacteria and B-35 rat neuroblastoma cells. Herein, we discuss the necessity of a careful sample preparation and provide an optimised protocol that allows to observe the details of cell ultrastructure (≥ 50 nm) with a minimum processing effort. Highlighting the versatility of morphometric descriptors, we present the most informative parameters and couple them with molecular processes. In this way, we indicate the wide range of information that can be collected through SEM imaging of biological materials that makes SEM a convenient screening method to detect cell pathology.
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Affiliation(s)
| | - Katarzyna Krukiewicz
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland;
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23
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Bacterial Filamentation Drives Colony Chirality. mBio 2021; 12:e0154221. [PMID: 34724813 PMCID: PMC8561393 DOI: 10.1128/mbio.01542-21] [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] [Indexed: 11/20/2022] Open
Abstract
Chirality is ubiquitous in nature, with consequences at the cellular and tissue scales. As Escherichia coli colonies expand radially, an orthogonal component of growth creates a pinwheel-like pattern that can be revealed by fluorescent markers. To elucidate the mechanistic basis of this colony chirality, we investigated its link to left-handed, single-cell twisting during E. coli elongation. While chemical and genetic manipulation of cell width altered single-cell twisting handedness, colonies ceased to be chiral rather than switching handedness, and anaerobic growth altered colony chirality without affecting single-cell twisting. Chiral angle increased with increasing temperature even when growth rate decreased. Unifying these findings, we discovered that colony chirality was associated with the propensity for cell filamentation. Inhibition of cell division accentuated chirality under aerobic growth and generated chirality under anaerobic growth. Thus, regulation of cell division is intrinsically coupled to colony chirality, providing a mechanism for tuning macroscale spatial patterning. IMPORTANCE Chiral objects, such as amino acids, are distinguishable from their mirror image. For living systems, the fundamental mechanisms relating cellular handedness to chirality at the multicellular scale remain largely mysterious. Here, we use chemical, genetic, and environmental perturbations of Escherichia coli to investigate whether pinwheel patterns in bacterial colonies are directly linked to single-cell growth behaviors. We discover that chirality can be abolished without affecting single-cell twisting; instead, the degree of chirality was linked to the proportion of highly elongated cells at the colony edge. Inhibiting cell division boosted the degree of chirality during aerobic growth and even introduced chirality to otherwise achiral colonies during anaerobic growth. These findings reveal a fascinating connection between cell division and macroscopic colony patterning.
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24
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Silvis MR, Rajendram M, Shi H, Osadnik H, Gray AN, Cesar S, Peters JM, Hearne CC, Kumar P, Todor H, Huang KC, Gross CA. Morphological and Transcriptional Responses to CRISPRi Knockdown of Essential Genes in Escherichia coli. mBio 2021; 12:e0256121. [PMID: 34634934 PMCID: PMC8510551 DOI: 10.1128/mbio.02561-21] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 09/09/2021] [Indexed: 01/03/2023] Open
Abstract
CRISPR interference (CRISPRi) has facilitated the study of essential genes in diverse organisms using both high-throughput and targeted approaches. Despite the promise of this technique, no comprehensive arrayed CRISPRi library targeting essential genes exists for the model bacterium Escherichia coli, or for any Gram-negative species. Here, we built and characterized such a library. Each of the ∼500 strains in our E. coli library contains an inducible, chromosomally integrated single guide RNA (sgRNA) targeting an essential (or selected nonessential) gene and can be mated with a pseudo-Hfr donor strain carrying a dcas9 cassette to create a CRISPRi knockdown strain. Using this system, we built an arrayed library of CRISPRi strains and performed population and single-cell growth and morphology measurements as well as targeted follow-up experiments. These studies found that inhibiting translation causes an extended lag phase, identified new modulators of cell morphology, and revealed that the morphogene mreB is subject to transcriptional feedback regulation, which is critical for the maintenance of morphology. Our findings highlight canonical and noncanonical roles for essential genes in numerous aspects of cellular homeostasis. IMPORTANCE Essential genes make up only ∼5 to 10% of the genetic complement in most organisms but occupy much of their protein synthesis and account for almost all antibiotic targets. Despite the importance of essential genes, their intractability has, until recently, hampered efforts to study them. CRISPRi has facilitated the study of essential genes by allowing inducible and titratable depletion. However, all large-scale CRISPRi studies in Gram-negative bacteria thus far have used plasmids to express CRISPRi components and have been constructed in pools, limiting their utility for targeted assays and complicating the determination of antibiotic effects. Here, we use a modular method to construct an arrayed library of chromosomally integrated CRISPRi strains targeting the essential genes of the model bacterium Escherichia coli. This library enables targeted studies of essential gene depletions and high-throughput determination of antibiotic targets and facilitates studies targeting the outer membrane, an essential component that serves as the major barrier to antibiotics.
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Affiliation(s)
- Melanie R. Silvis
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Manohary Rajendram
- Department of Bioengineering, Stanford University, Stanford, California, USA
| | - Handuo Shi
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Hendrik Osadnik
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Andrew N. Gray
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Spencer Cesar
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Jason M. Peters
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Cameron C. Hearne
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Parth Kumar
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Horia Todor
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, California, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
| | - Carol A. Gross
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
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25
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Kamariza M, Keyser SGL, Utz A, Knapp BD, Ealand C, Ahn G, Cambier CJ, Chen T, Kana B, Huang KC, Bertozzi CR. Toward Point-of-Care Detection of Mycobacterium tuberculosis: A Brighter Solvatochromic Probe Detects Mycobacteria within Minutes. JACS AU 2021; 1:1368-1379. [PMID: 34604847 PMCID: PMC8479770 DOI: 10.1021/jacsau.1c00173] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Indexed: 05/17/2023]
Abstract
There is an urgent need for point-of-care tuberculosis (TB) diagnostic methods that are fast, inexpensive, and operationally simple. Here, we report on a bright solvatochromic dye trehalose conjugate that specifically detects Mycobacterium tuberculosis (Mtb) in minutes. 3-Hydroxychromone (3HC) dyes, known for having high fluorescence quantum yields, exhibit shifts in fluorescence intensity in response to changes in environmental polarity. We synthesized two analogs of 3HC-trehalose conjugates (3HC-2-Tre and 3HC-3-Tre) and determined that 3HC-3-Tre has exceptionally favorable properties for Mtb detection. 3HC-3-Tre-labeled mycobacterial cells displayed a 10-fold increase in fluorescence intensity compared to our previous reports on the dye 4,4-N,N-dimethylaminonapthalimide (DMN-Tre). Excitingly, we detected fluorescent Mtb cells within 10 min of probe treatment. Thus, 3HC-3-Tre permits rapid visualization of mycobacteria that ultimately could empower improved Mtb detection at the point-of-care in low-resource settings.
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Affiliation(s)
- Mireille Kamariza
- Department
of Biology, Stanford University, Stanford, California 94305, United States
| | - Samantha G. L. Keyser
- Department
of Chemistry, University of California,
Berkeley, Berkeley, California 94720, United States
| | - Ashley Utz
- Department
of Biology, Stanford University, Stanford, California 94305, United States
| | - Benjamin D. Knapp
- Biophysics
Program, Stanford University, Stanford, California 94305, United States
| | - Christopher Ealand
- Department
of Science and Technology/National Research Foundation Centre of Excellence
for Biomedical Tuberculosis Research, Faculty of Health Sciences, University of Witwatersrand, National Health Laboratory Service, Johannesburg 2000, South Africa
| | - Green Ahn
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - C. J. Cambier
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Teresia Chen
- Department
of Biology, Stanford University, Stanford, California 94305, United States
| | - Bavesh Kana
- Department
of Science and Technology/National Research Foundation Centre of Excellence
for Biomedical Tuberculosis Research, Faculty of Health Sciences, University of Witwatersrand, National Health Laboratory Service, Johannesburg 2000, South Africa
- Medical
Research Council−Centre for the AIDS Programme of Research
in South Africa (CAPRISA) HIV-TB Pathogenesis and Treatment Research
Unit, Durban 4013, South Africa
| | - Kerwyn Casey Huang
- Biophysics
Program, Stanford University, Stanford, California 94305, United States
- Department
of Bioengineering, Stanford University, Stanford, California 94305, United States
- Department
of Microbiology and Immunology, Stanford
University School of Medicine, Stanford, California 94305, United States
- Chan
Zuckerberg Biohub, San Francisco, California 94158, United States
| | - Carolyn R. Bertozzi
- Department
of Chemistry, University of California,
Berkeley, Berkeley, California 94720, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
- Howard
Hughes Medical Institute, Stanford University, Stanford, California 94305, United States
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26
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Sun J, Shi H, Huang KC. Hyperosmotic Shock Transiently Accelerates Constriction Rate in Escherichia coli. Front Microbiol 2021; 12:718600. [PMID: 34489908 PMCID: PMC8418109 DOI: 10.3389/fmicb.2021.718600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/26/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial cells in their natural environments encounter rapid and large changes in external osmolality. For instance, enteric bacteria such as Escherichia coli experience a rapid decrease when they exit from host intestines. Changes in osmolality alter the mechanical load on the cell envelope, and previous studies have shown that large osmotic shocks can slow down bacterial growth and impact cytoplasmic diffusion. However, it remains unclear how cells maintain envelope integrity and regulate envelope synthesis in response to osmotic shocks. In this study, we developed an agarose pad-based protocol to assay envelope stiffness by measuring population-averaged cell length before and after a hyperosmotic shock. Pad-based measurements exhibited an apparently larger length change compared with single-cell dynamics in a microfluidic device, which we found was quantitatively explained by a transient increase in division rate after the shock. Inhibiting cell division led to consistent measurements between agarose pad-based and microfluidic measurements. Directly after hyperosmotic shock, FtsZ concentration and Z-ring intensity increased, and the rate of septum constriction increased. These findings establish an agarose pad-based protocol for quantifying cell envelope stiffness, and demonstrate that mechanical perturbations can have profound effects on bacterial physiology.
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Affiliation(s)
- Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA, United States
| | - Handuo Shi
- Department of Bioengineering, Stanford University, Stanford, CA, United States.,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, United States
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, United States.,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, United States.,Chan Zuckerberg Biohub, San Francisco, CA, United States
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27
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Robust surface-to-mass coupling and turgor-dependent cell width determine bacterial dry-mass density. Proc Natl Acad Sci U S A 2021; 118:2021416118. [PMID: 34341116 PMCID: PMC8364103 DOI: 10.1073/pnas.2021416118] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Intracellular biomass density is an important variable for cellular physiology. It defines the crowded state of the cytoplasm and thus influences macromolecular interactions and transport. To control density during growth, bacteria must expand their cell volumes in synchrony with biomass. The regulation of volume growth and biomass density remain fundamentally not understood—in bacteria or any other organism. Using advanced microscopy, we demonstrate that cells control dry-mass density indirectly through two independent processes. First, cells expand surface area, rather than volume, in proportion with biomass growth. Second, cell width is controlled independently, with an important influence of turgor pressure. Our findings overturn a long-standing paradigm of mass-density constancy in bacteria and reveal fundamental determinants of dry-mass density and shape. During growth, cells must expand their cell volumes in coordination with biomass to control the level of cytoplasmic macromolecular crowding. Dry-mass density, the average ratio of dry mass to volume, is roughly constant between different nutrient conditions in bacteria, but it remains unknown whether cells maintain dry-mass density constant at the single-cell level and during nonsteady conditions. Furthermore, the regulation of dry-mass density is fundamentally not understood in any organism. Using quantitative phase microscopy and an advanced image-analysis pipeline, we measured absolute single-cell mass and shape of the model organisms Escherichia coli and Caulobacter crescentus with improved precision and accuracy. We found that cells control dry-mass density indirectly by expanding their surface, rather than volume, in direct proportion to biomass growth—according to an empirical surface growth law. At the same time, cell width is controlled independently. Therefore, cellular dry-mass density varies systematically with cell shape, both during the cell cycle or after nutrient shifts, while the surface-to-mass ratio remains nearly constant on the generation time scale. Transient deviations from constancy during nutrient shifts can be reconciled with turgor-pressure variations and the resulting elastic changes in surface area. Finally, we find that plastic changes of cell width after nutrient shifts are likely driven by turgor variations, demonstrating an important regulatory role of mechanical forces for width regulation. In conclusion, turgor-dependent cell width and a slowly varying surface-to-mass coupling constant are the independent variables that determine dry-mass density.
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28
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Halladin DK, Ortega FE, Ng KM, Footer MJ, Mitić NS, Malkov SN, Gopinathan A, Huang KC, Theriot JA. Entropy-driven translocation of disordered proteins through the Gram-positive bacterial cell wall. Nat Microbiol 2021; 6:1055-1065. [PMID: 34326523 DOI: 10.1038/s41564-021-00942-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/28/2021] [Indexed: 02/07/2023]
Abstract
In Gram-positive bacteria, a thick cross-linked cell wall separates the membrane from the extracellular space. Some surface-exposed proteins, such as the Listeria monocytogenes actin nucleation-promoting factor ActA, remain associated with the bacterial membrane but somehow thread through tens of nanometres of cell wall to expose their amino terminus to the exterior. Here, we report that entropy enables the translocation of disordered transmembrane proteins through the Gram-positive cell wall. We build a physical model, which predicts that the entropic constraint imposed by a thin periplasm is sufficient to drive the translocation of an intrinsically disordered protein such as ActA across a porous barrier similar to a peptidoglycan cell wall. We experimentally validate our model and show that ActA translocation depends on the cell-envelope dimensions and disordered-protein length, and that translocation is reversible. We also show that disordered regions of eukaryotic proteins can translocate Gram-positive cell walls via entropy. We propose that entropic forces are sufficient to drive the translocation of specific proteins to the outer surface.
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Affiliation(s)
- David K Halladin
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Fabian E Ortega
- Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| | - Katharine M Ng
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.,Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Matthew J Footer
- Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA.,Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Nenad S Mitić
- Faculty of Mathematics, University of Belgrade, Belgrade, Serbia
| | - Saša N Malkov
- Faculty of Mathematics, University of Belgrade, Belgrade, Serbia
| | - Ajay Gopinathan
- Department of Physics, University of California, Merced, CA, USA
| | - Kerwyn Casey Huang
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
| | - Julie A Theriot
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biochemistry and Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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29
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Garner EC. Toward a Mechanistic Understanding of Bacterial Rod Shape Formation and Regulation. Annu Rev Cell Dev Biol 2021; 37:1-21. [PMID: 34186006 DOI: 10.1146/annurev-cellbio-010521-010834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One of the most common bacterial shapes is a rod, yet we have a limited understanding of how this simple shape is constructed. While only six proteins are required for rod shape, we are just beginning to understand how they self-organize to build the micron-sized enveloping structures that define bacterial shape out of nanometer-sized glycan strains. Here, we detail and summarize the insights gained over the last 20 years into this complex problem that have been achieved with a wide variety of different approaches. We also explain and compare both current and past models of rod shape formation and maintenance and then highlight recent insights into how the Rod complex might be regulated. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA;
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30
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Abstract
Environmental fluctuations are a common challenge for single-celled organisms; enteric bacteria such as Escherichia coli experience dramatic changes in nutrient availability, pH, and temperature during their journey into and out of the host. While the effects of altered nutrient availability on gene expression and protein synthesis are well known, their impacts on cytoplasmic dynamics and cell morphology have been largely overlooked. Here, we discover that depletion of utilizable nutrients results in shrinkage of E. coli's inner membrane from the cell wall. Shrinkage was accompanied by an ∼17% reduction in cytoplasmic volume and a concurrent increase in periplasmic volume. Inner membrane retraction after sudden starvation occurred almost exclusively at the new cell pole. This phenomenon was distinct from turgor-mediated plasmolysis and independent of new transcription, translation, or canonical starvation-sensing pathways. Cytoplasmic dry-mass density increased during shrinkage, suggesting that it is driven primarily by loss of water. Shrinkage was reversible: upon a shift to nutrient-rich medium, expansion started almost immediately at a rate dependent on carbon source quality. A robust entry into and recovery from shrinkage required the Tol-Pal system, highlighting the importance of envelope coupling during shrinkage and recovery. Klebsiella pneumoniae also exhibited shrinkage when shifted to carbon-free conditions, suggesting a conserved phenomenon. These findings demonstrate that even when Gram-negative bacterial growth is arrested, cell morphology and physiology are still dynamic.
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31
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Odermatt PD, Miettinen TP, Lemière J, Kang JH, Bostan E, Manalis SR, Huang KC, Chang F. Variations of intracellular density during the cell cycle arise from tip-growth regulation in fission yeast. eLife 2021; 10:64901. [PMID: 34100714 PMCID: PMC8221806 DOI: 10.7554/elife.64901] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 06/07/2021] [Indexed: 12/24/2022] Open
Abstract
Intracellular density impacts the physical nature of the cytoplasm and can globally affect cellular processes, yet density regulation remains poorly understood. Here, using a new quantitative phase imaging method, we determined that dry-mass density in fission yeast is maintained in a narrow distribution and exhibits homeostatic behavior. However, density varied during the cell cycle, decreasing during G2, increasing in mitosis and cytokinesis, and dropping rapidly at cell birth. These density variations were explained by a constant rate of biomass synthesis, coupled to slowdown of volume growth during cell division and rapid expansion post-cytokinesis. Arrest at specific cell-cycle stages exacerbated density changes. Spatially heterogeneous patterns of density suggested links between density regulation, tip growth, and intracellular osmotic pressure. Our results demonstrate that systematic density variations during the cell cycle are predominantly due to modulation of volume expansion, and reveal functional consequences of density gradients and cell-cycle arrests.
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Affiliation(s)
- Pascal D Odermatt
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States.,Department of Bioengineering, Stanford University, Stanford, United States
| | - Teemu P Miettinen
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,MRC Laboratory for Molecular Cell Biology, University College, London, United Kingdom
| | - Joël Lemière
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
| | - Joon Ho Kang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Physics, Massachusetts Institute of Technology, Cambridge, United States.,Brain Science Institute, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Emrah Bostan
- Informatics Institute, University of Amsterdam, Amsterdamn, Netherlands
| | - Scott R Manalis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, United States.,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, United States.,Chan Zuckerberg Biohub, San Francisco, United States
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, United States
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32
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Shiver AL, Osadnik H, Peters JM, Mooney RA, Wu PI, Henry KK, Braberg H, Krogan NJ, Hu JC, Landick R, Huang KC, Gross CA. Chemical-genetic interrogation of RNA polymerase mutants reveals structure-function relationships and physiological tradeoffs. Mol Cell 2021; 81:2201-2215.e9. [PMID: 34019789 PMCID: PMC8484514 DOI: 10.1016/j.molcel.2021.04.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 01/25/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022]
Abstract
The multi-subunit bacterial RNA polymerase (RNAP) and its associated regulators carry out transcription and integrate myriad regulatory signals. Numerous studies have interrogated RNAP mechanism, and RNAP mutations drive Escherichia coli adaptation to many health- and industry-relevant environments, yet a paucity of systematic analyses hampers our understanding of the fitness trade-offs from altering RNAP function. Here, we conduct a chemical-genetic analysis of a library of RNAP mutants. We discover phenotypes for non-essential insertions, show that clustering mutant phenotypes increases their predictive power for drawing functional inferences, and demonstrate that some RNA polymerase mutants both decrease average cell length and prevent killing by cell-wall targeting antibiotics. Our findings demonstrate that RNAP chemical-genetic interactions provide a general platform for interrogating structure-function relationships in vivo and for identifying physiological trade-offs of mutations, including those relevant for disease and biotechnology. This strategy should have broad utility for illuminating the role of other important protein complexes.
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Affiliation(s)
- Anthony L Shiver
- Graduate Group in Biophysics, University of California San Francisco, San Francisco, CA 94158, USA; Department of Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Hendrik Osadnik
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Jason M Peters
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94158, USA
| | - Rachel A Mooney
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Peter I Wu
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Kemardo K Henry
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hannes Braberg
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute, University of California San Francisco, San Francisco, CA 94158, USA; Gladstone Institutes, San Francisco, CA 94158, USA; Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - James C Hu
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Robert Landick
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University School of Medicine, 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.
| | - Carol A Gross
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA 94158, USA; Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, CA 94158, USA; California Institute of Quantitative Biology, University of California San Francisco, San Francisco, CA 94158, USA.
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33
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Barton B, Grinnell A, Morgenstein RM. Disruption of the MreB Elongasome Is Overcome by Mutations in the Tricarboxylic Acid Cycle. Front Microbiol 2021; 12:664281. [PMID: 33968001 PMCID: PMC8102728 DOI: 10.3389/fmicb.2021.664281] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 04/06/2021] [Indexed: 01/20/2023] Open
Abstract
The bacterial actin homolog, MreB, is highly conserved among rod-shaped bacteria and essential for growth under normal growth conditions. MreB directs the localization of cell wall synthesis and loss of MreB results in round cells and death. Using the MreB depolymerizing drug, A22, we show that changes to central metabolism through deletion of malate dehydrogenase from the tricarboxylic acid (TCA) cycle results in cells with an increased tolerance to A22. We hypothesize that deletion of malate dehydrogenase leads to the upregulation of gluconeogenesis resulting in an increase in cell wall precursors. Consistent with this idea, metabolite analysis revealed that malate dehydrogenase (mdh) deletion cells possess elevated levels of several glycolysis/gluconeogenesis compounds and the cell wall precursor, uridine diphosphate N-acetylglucosamine (UDP-NAG). In agreement with these results, the increased A22 resistance phenotype can be recapitulated through the addition of glucose to the media. Finally, we show that this increase in antibiotic tolerance is not specific to A22 but also applies to the cell wall-targeting antibiotic, mecillinam.
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Affiliation(s)
- Brody Barton
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Addison Grinnell
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Randy M Morgenstein
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
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34
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Zhu L, Rajendram M, Huang KC. Effects of fixation on bacterial cellular dimensions and integrity. iScience 2021; 24:102348. [PMID: 33912815 PMCID: PMC8066382 DOI: 10.1016/j.isci.2021.102348] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 01/25/2021] [Accepted: 03/18/2021] [Indexed: 11/22/2022] Open
Abstract
Fixation facilitates imaging of subcellular localization and cell morphology, yet it remains unknown how fixation affects cellular dimensions and intracellular fluorescence patterns, particularly during long-term storage. Here, we characterized the effects of multiple fixatives on several bacterial species. Fixation generally reduced cell length by 5-15%; single-cell tracking in microfluidics revealed that the length decrease was an aggregate effect of many steps in the fixation protocol and that fluorescence of cytoplasmic GFP but not membrane-bound MreB-msfGFP was rapidly lost with formaldehyde-based fixatives. Cellular dimensions were preserved in formaldehyde-based fixatives for ≥4 days, but methanol caused length to decrease. Although methanol preserved cytoplasmic fluorescence better than formaldehyde-based fixatives, some Escherichia coli cells were able to grow directly after fixation. Moreover, methanol fixation caused lysis in a subpopulation of cells, with virtually all Bacillus subtilis cells lysing after one day. These findings highlight tradeoffs between maintenance of fluorescence and membrane integrity for future applications of fixation.
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Affiliation(s)
- Lillian Zhu
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Manohary Rajendram
- Department of Bioengineering, 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
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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35
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An alternative resource allocation strategy in the chemolithoautotrophic archaeon Methanococcus maripaludis. Proc Natl Acad Sci U S A 2021; 118:2025854118. [PMID: 33879571 DOI: 10.1073/pnas.2025854118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Most microorganisms in nature spend the majority of time in a state of slow or zero growth and slow metabolism under limited energy or nutrient flux rather than growing at maximum rates. Yet, most of our knowledge has been derived from studies on fast-growing bacteria. Here, we systematically characterized the physiology of the methanogenic archaeon Methanococcus maripaludis during slow growth. M. maripaludis was grown in continuous culture under energy (formate)-limiting conditions at different dilution rates ranging from 0.09 to 0.002 h-1, the latter corresponding to 1% of its maximum growth rate under laboratory conditions (0.23 h-1). While the specific rate of methanogenesis correlated with growth rate as expected, the fraction of cellular energy used for maintenance increased and the maintenance energy per biomass decreased at slower growth. Notably, proteome allocation between catabolic and anabolic pathways was invariant with growth rate. Unexpectedly, cells maintained their maximum methanogenesis capacity over a wide range of growth rates, except for the lowest rates tested. Cell size, cellular DNA, RNA, and protein content as well as ribosome numbers also were largely invariant with growth rate. A reduced protein synthesis rate during slow growth was achieved by a reduction in ribosome activity rather than via the number of cellular ribosomes. Our data revealed a resource allocation strategy of a methanogenic archaeon during energy limitation that is fundamentally different from commonly studied versatile chemoheterotrophic bacteria such as E. coli.
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36
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Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments. Nat Commun 2021; 12:1975. [PMID: 33785742 PMCID: PMC8009875 DOI: 10.1038/s41467-021-22092-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 02/12/2021] [Indexed: 11/23/2022] Open
Abstract
The steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments. Bacterial cells actively change their size and shape in response to external environments. Here, Shi et al. explore how cells regulate their morphology during rapid environmental changes, showing that the characteristic dynamics of surface area-to-volume ratio are conserved across genetic and chemical perturbations, as well as across species and growth temperatures.
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37
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Mutability of demographic noise in microbial range expansions. ISME JOURNAL 2021; 15:2643-2654. [PMID: 33746203 PMCID: PMC8397776 DOI: 10.1038/s41396-021-00951-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 02/24/2021] [Indexed: 11/13/2022]
Abstract
Demographic noise, the change in the composition of a population due to random birth and death events, is an important driving force in evolution because it reduces the efficacy of natural selection. Demographic noise is typically thought to be set by the population size and the environment, but recent experiments with microbial range expansions have revealed substantial strain-level differences in demographic noise under the same growth conditions. Many genetic and phenotypic differences exist between strains; to what extent do single mutations change the strength of demographic noise? To investigate this question, we developed a high-throughput method for measuring demographic noise in colonies without the need for genetic manipulation. By applying this method to 191 randomly-selected single gene deletion strains from the E. coli Keio collection, we find that a typical single gene deletion mutation decreases demographic noise by 8% (maximal decrease: 81%). We find that the strength of demographic noise is an emergent trait at the population level that can be predicted by colony-level traits but not cell-level traits. The observed differences in demographic noise from single gene deletions can increase the establishment probability of beneficial mutations by almost an order of magnitude (compared to in the wild type). Our results show that single mutations can substantially alter adaptation through their effects on demographic noise and suggest that demographic noise can be an evolvable trait of a population.
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Gilmore MC, Ritzl-Rinkenberger B, Cava F. An updated toolkit for exploring bacterial cell wall structure and dynamics. Fac Rev 2021; 10:14. [PMID: 33659932 PMCID: PMC7894271 DOI: 10.12703/r/10-14] [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] [Indexed: 11/15/2022] Open
Abstract
The bacterial cell wall is made primarily from peptidoglycan, a complex biomolecule which forms a bag-like exoskeleton that envelops the cell. As it is unique to bacteria and typically essential for their growth and survival, it represents one of the most successful targets for antibiotics. Although peptidoglycan has been studied intensively for over 50 years, the past decade has seen major steps in our understanding of this molecule because of the advent of new analytical and imaging methods. Here, we outline the most recent developments in tools that have helped to elucidate peptidoglycan structure and dynamics.
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Affiliation(s)
- Michael C Gilmore
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Barbara Ritzl-Rinkenberger
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Department of Molecular Biology, Umeå University, Umeå, Sweden
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CcrZ is a pneumococcal spatiotemporal cell cycle regulator that interacts with FtsZ and controls DNA replication by modulating the activity of DnaA. Nat Microbiol 2021; 6:1175-1187. [PMID: 34373624 PMCID: PMC8387234 DOI: 10.1038/s41564-021-00949-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/07/2021] [Indexed: 02/07/2023]
Abstract
Most bacteria replicate and segregate their DNA concomitantly while growing, before cell division takes place. How bacteria synchronize these different cell cycle events to ensure faithful chromosome inheritance by daughter cells is poorly understood. Here, we identify Cell Cycle Regulator protein interacting with FtsZ (CcrZ) as a conserved and essential protein in pneumococci and related Firmicutes such as Bacillus subtilis and Staphylococcus aureus. CcrZ couples cell division with DNA replication by controlling the activity of the master initiator of DNA replication, DnaA. The absence of CcrZ causes mis-timed and reduced initiation of DNA replication, which subsequently results in aberrant cell division. We show that CcrZ from Streptococcus pneumoniae interacts directly with the cytoskeleton protein FtsZ, which places CcrZ in the middle of the newborn cell where the DnaA-bound origin is positioned. This work uncovers a mechanism for control of the bacterial cell cycle in which CcrZ controls DnaA activity to ensure that the chromosome is replicated at the right time during the cell cycle.
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Straightening up for life in a biofilm. Proc Natl Acad Sci U S A 2020; 117:31573-31574. [PMID: 33203672 DOI: 10.1073/pnas.2021127117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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41
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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: 3.0] [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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Knapp BD, Zhu L, Huang KC. SiCTeC: An inexpensive, easily assembled Peltier device for rapid temperature shifting during single-cell imaging. PLoS Biol 2020; 18:e3000786. [PMID: 33156840 PMCID: PMC7685484 DOI: 10.1371/journal.pbio.3000786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/24/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022] Open
Abstract
Single-cell imaging, combined with recent advances in image analysis and microfluidic technologies, have enabled fundamental discoveries of cellular responses to chemical perturbations that are often obscured by traditional liquid-culture experiments. Temperature is an environmental variable well known to impact growth and to elicit specific stress responses at extreme values; it is often used as a genetic tool to interrogate essential genes. However, the dynamic effects of temperature shifts have remained mostly unstudied at the single-cell level, due largely to engineering challenges related to sample stability, heatsink considerations, and temperature measurement and feedback. Additionally, the few commercially available temperature-control platforms are costly. Here, we report an inexpensive (<$110) and modular Single-Cell Temperature Controller (SiCTeC) device for microbial imaging-based on straightforward modifications of the typical slide-sample-coverslip approach to microbial imaging-that controls temperature using a ring-shaped Peltier module and microcontroller feedback. Through stable and precise (±0.15°C) temperature control, SiCTeC achieves reproducible and fast (1-2 min) temperature transitions with programmable waveforms between room temperature and 45°C with an air objective. At the device's maximum temperature of 89°C, SiCTeC revealed that Escherichia coli cells progressively shrink and lose cellular contents. During oscillations between 30°C and 37°C, cells rapidly adapted their response to temperature upshifts. Furthermore, SiCTeC enabled the discovery of rapid morphological changes and enhanced sensitivity to substrate stiffness during upshifts to nonpermissive temperatures in temperature-sensitive mutants of cell-wall synthesis enzymes. Overall, the simplicity and affordability of SiCTeC empowers future studies of the temperature dependence of single-cell physiology.
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Affiliation(s)
- Benjamin D. Knapp
- Biophysics Program, Stanford University, Stanford, California, United States of America
| | - Lillian Zhu
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
| | - Kerwyn Casey Huang
- Biophysics Program, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Stanford University, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America
- Chan Zuckerberg Biohub, San Francisco, California, United States of America
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The inner membrane protein YhdP modulates the rate of anterograde phospholipid flow in Escherichia coli. Proc Natl Acad Sci U S A 2020; 117:26907-26914. [PMID: 33046656 DOI: 10.1073/pnas.2015556117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is a selective permeability barrier that allows uptake of nutrients while simultaneously protecting the cell from harmful compounds. The basic pathways and molecular machinery responsible for transporting lipopolysaccharides (LPS), lipoproteins, and β-barrel proteins to the OM have been identified, but very little is known about phospholipid (PL) transport. To identify genes capable of affecting PL transport, we screened for genetic interactions with mlaA*, a mutant in which anterograde PL transport causes the inner membrane (IM) to shrink and eventually rupture; characterization of mlaA*-mediated lysis suggested that PL transport can occur via a high-flux diffusive flow mechanism. We found that YhdP, an IM protein involved in maintaining the OM permeability barrier, modulates the rate of PL transport during mlaA*-mediated lysis. Deletion of yhdP from mlaA* reduced the rate of IM transport to the OM by 50%, slowing shrinkage of the IM and delaying lysis. As a result, the weakened OM of ∆yhdP cells was further compromised and ruptured before the IM during mlaA*-mediated death. These findings demonstrate the existence of a high-flux diffusive pathway for PL flow in Escherichia coli that is modulated by YhdP.
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44
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Correlated chromosomal periodicities according to the growth rate and gene expression. Sci Rep 2020; 10:15531. [PMID: 32968121 PMCID: PMC7511328 DOI: 10.1038/s41598-020-72389-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/10/2020] [Indexed: 12/02/2022] Open
Abstract
Linking genetic information to population fitness is crucial to understanding living organisms. Despite the abundant knowledge of the genetic contribution to growth, the overall patterns/features connecting genes, their expression, and growth remain unclear. To reveal the quantitative and direct connections, systematic growth assays of single-gene knockout Escherichia coli strains under both rich and poor nutritional conditions were performed; subsequently, the resultant growth rates were associated with the original expression levels of the knockout genes in the parental genome. Comparative analysis of growth and the transcriptome identified not only the nutritionally differentiated fitness cost genes but also a significant correlation between the growth rates of the single-gene knockout strains and the original expression levels of these knockout genes in the parental strain, regardless of the nutritional variation. In addition, the coordinated chromosomal periodicities of the wild-type transcriptome and the growth rates of the strains lacking the corresponding genes were observed. The common six-period periodicity was somehow attributed to the essential genes, although the underlying mechanism remains to be addressed. The correlated chromosomal periodicities associated with the gene expression-growth dataset were highly valuable for bacterial growth prediction and discovering the working principles governing minimal genetic information.
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Yang L, Ghosh RP, Franklin JM, Chen S, You C, Narayan RR, Melcher ML, Liphardt JT. NuSeT: A deep learning tool for reliably separating and analyzing crowded cells. PLoS Comput Biol 2020; 16:e1008193. [PMID: 32925919 PMCID: PMC7515182 DOI: 10.1371/journal.pcbi.1008193] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 09/24/2020] [Accepted: 07/25/2020] [Indexed: 01/30/2023] Open
Abstract
Segmenting cell nuclei within microscopy images is a ubiquitous task in biological research and clinical applications. Unfortunately, segmenting low-contrast overlapping objects that may be tightly packed is a major bottleneck in standard deep learning-based models. We report a Nuclear Segmentation Tool (NuSeT) based on deep learning that accurately segments nuclei across multiple types of fluorescence imaging data. Using a hybrid network consisting of U-Net and Region Proposal Networks (RPN), followed by a watershed step, we have achieved superior performance in detecting and delineating nuclear boundaries in 2D and 3D images of varying complexities. By using foreground normalization and additional training on synthetic images containing non-cellular artifacts, NuSeT improves nuclear detection and reduces false positives. NuSeT addresses common challenges in nuclear segmentation such as variability in nuclear signal and shape, limited training sample size, and sample preparation artifacts. Compared to other segmentation models, NuSeT consistently fares better in generating accurate segmentation masks and assigning boundaries for touching nuclei.
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Affiliation(s)
- Linfeng Yang
- Bioengineering, Stanford University, Stanford, CA, United States of America
- BioX Institute, Stanford University, Stanford, CA, United States of America
- ChEM-H, Stanford University, Stanford, CA, United States of America
- Cell Biology Division, Stanford Cancer Institute, Stanford, CA, United States of America
| | - Rajarshi P. Ghosh
- Bioengineering, Stanford University, Stanford, CA, United States of America
- BioX Institute, Stanford University, Stanford, CA, United States of America
- ChEM-H, Stanford University, Stanford, CA, United States of America
- Cell Biology Division, Stanford Cancer Institute, Stanford, CA, United States of America
| | - J. Matthew Franklin
- Bioengineering, Stanford University, Stanford, CA, United States of America
- BioX Institute, Stanford University, Stanford, CA, United States of America
- ChEM-H, Stanford University, Stanford, CA, United States of America
- Cell Biology Division, Stanford Cancer Institute, Stanford, CA, United States of America
- Chemical Engineering, Stanford University, Stanford, CA, United States of America
| | - Simon Chen
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Chenyu You
- Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Raja R. Narayan
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Marc L. Melcher
- Department of Surgery, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Jan T. Liphardt
- Bioengineering, Stanford University, Stanford, CA, United States of America
- BioX Institute, Stanford University, Stanford, CA, United States of America
- ChEM-H, Stanford University, Stanford, CA, United States of America
- Cell Biology Division, Stanford Cancer Institute, Stanford, CA, United States of America
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AimB Is a Small Protein Regulator of Cell Size and MreB Assembly. Biophys J 2020; 119:593-604. [PMID: 32416080 DOI: 10.1016/j.bpj.2020.04.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/17/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022] Open
Abstract
The MreB actin-like cytoskeleton assembles into dynamic polymers that coordinate cell shape in many bacteria. In contrast to most other cytoskeleton systems, few MreB-interacting proteins have been well characterized. Here, we identify a small protein from Caulobacter crescentus, an assembly inhibitor of MreB (AimB). AimB overexpression mimics inhibition of MreB polymerization, leading to increased cell width and MreB delocalization. Furthermore, aimB appears to be essential, and its depletion results in decreased cell width and increased resistance to A22, a small-molecule inhibitor of MreB assembly. Molecular dynamics simulations suggest that AimB binds MreB at its monomer-monomer protofilament interaction cleft and that this interaction is favored for C. crescentus MreB over Escherichia coli MreB because of a closer match in the degree of opening with AimB size, suggesting coevolution of AimB with MreB conformational dynamics in C. crescentus. We support this model through functional analysis of point mutants in both AimB and MreB, photo-cross-linking studies with site-specific unnatural amino acids, and species-specific activity of AimB. Together, our findings are consistent with AimB promoting MreB dynamics by inhibiting monomer-monomer assembly interactions, representing a new mechanism for regulating actin-like polymers and the first identification of a non-toxin MreB assembly inhibitor. Because AimB has only 104 amino acids and small proteins are often poorly characterized, our work suggests the possibility of more bacterial cytoskeletal regulators to be found in this class. Thus, like FtsZ and eukaryotic actin, MreB may have a rich repertoire of regulators to tune its precise assembly and dynamics.
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Abstract
For bacteria, maintaining higher internal solute concentrations than those present in the environment allows cells to take up water. As a result, survival is challenging in high-osmolarity environments. To investigate how bacteria adapt to high-osmolarity environments, we maintained Escherichia coli in a variety of high-osmolarity solutions for hundreds of generations. We found that the evolved populations adopted different strategies to improve their growth rates depending on the osmotic passaging condition, either generally adapting to high-osmolarity conditions or better metabolizing the osmolyte as a carbon source. Single-cell imaging demonstrated that enhanced fitness was coupled to faster growth, and metagenomic sequencing revealed mutations that reflected growth trade-offs across osmolarities. Our study demonstrated the utility of long-term evolution experiments for probing adaptation occurring during environmental stress. Bacteria must maintain a cytosolic osmolarity higher than that of their environment in order to take up water. High-osmolarity environments therefore present formidable stress to bacteria. To explore the evolutionary mechanisms by which bacteria adapt to high-osmolarity environments, we selected Escherichia coli in media with a variety of osmolytes and concentrations for 250 generations. Adaptation was osmolyte dependent, with sorbitol stress generally resulting in increased fitness under conditions with higher osmolarity, while selection in high concentrations of proline resulted in increased fitness specifically on proline. Consistent with these phenotypes, sequencing of the evolved populations showed that passaging in proline resulted in specific mutations in an associated metabolic pathway that increased the ability to utilize proline for growth, while evolution in sorbitol resulted in mutations in many different genes that generally resulted in improved growth under high-osmolarity conditions at the expense of growth at low osmolarity. High osmolarity decreased the growth rate but increased the mean cell volume compared with growth on proline as the sole carbon source, demonstrating that osmolarity-induced changes in growth rate and cell size follow an orthogonal relationship from the classical Growth Law relating cell size and nutrient quality. Isolates from a sorbitol-evolved population that captured the likely temporal sequence of mutations revealed by metagenomic sequencing demonstrated a trade-off between growth at high osmolarity and growth at low osmolarity. Our report highlights the utility of experimental evolution for dissecting complex cellular networks and environmental interactions, particularly in the case of behaviors that can involve both specific and general metabolic stressors.
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48
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Khare S, Hsin J, Sorto NA, Nepomuceno GM, Shaw JT, Shi H, Huang KC. FtsZ-Independent Mechanism of Division Inhibition by the Small Molecule PC190723 in Escherichia coli. ACTA ACUST UNITED AC 2020; 3:e1900021. [PMID: 32648693 DOI: 10.1002/adbi.201900021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/07/2019] [Indexed: 11/12/2022]
Abstract
While cell division is a critical process in cellular proliferation, very few antibiotics have been identified that target the bacterial cell-division machinery. Recent studies have shown that the small molecule PC190723 inhibits cell division in several Gram-positive bacteria, with a hypothesized mechanism of action involving direct targeting of the tubulin homolog FtsZ, which is essential for division in virtually all bacterial species. Here, it is shown that PC190723 also inhibits cell division in the Gram-negative bacterium Escherichia coli if the outer membrane permeability barrier is compromised genetically or chemically. The results show that the equivalent FtsZ mutations conferring PC190723 resistance in Staphylococcus aureus do not protect E. coli against PC190723, and that suppressors of PC190723 sensitivity in E. coli, which do not generically decrease outer membrane permeability, do not map to FtsZ or other division proteins. These suppressors display a wide range of morphological and growth phenotypes, and one exhibits a death phenotype in the stationary phase similar to that of a mutant with disrupted lipid homeostasis. Finally, a complementing FtsZ-msfGFP fusion is used to show that PC190723 does not affect the Z-ring structure. Taken together, the findings suggest that PC190723 inhibits growth and division in E. coli without targeting FtsZ. This study highlights the importance of utilizing a combination of genetic, chemical, and single-cell approaches to dissect the mechanisms of action of new antibiotics, which are not necessarily conserved across bacterial species.
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Affiliation(s)
- Somya Khare
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Jen Hsin
- Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA
| | - Nohemy A Sorto
- Department of Chemistry, University of California at Davis, Davis, CA, 95616, USA
| | | | - Jared T Shaw
- Department of Chemistry, University of California at Davis, Davis, CA, 95616, USA
| | - Handuo Shi
- Department of Bioengineering, 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, Stanford, CA, 94305, USA.,Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA
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Rhodeland B, Hoeger K, Ursell T. Bacterial surface motility is modulated by colony-scale flow and granular jamming. J R Soc Interface 2020; 17:20200147. [PMID: 32574537 DOI: 10.1098/rsif.2020.0147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Microbes routinely face the challenge of acquiring territory and resources on wet surfaces. Cells move in large groups inside thin, surface-bound water layers, often achieving speeds of 30 µm s-1 within this environment, where viscous forces dominate over inertial forces (low Reynolds number). The canonical Gram-positive bacterium Bacillus subtilis is a model organism for the study of collective migration over surfaces with groups exhibiting motility on length-scales three orders of magnitude larger than themselves within a few doubling times. Genetic and chemical studies clearly show that the secretion of endogenous surfactants and availability of free surface water are required for this fast group motility. Here, we show that: (i) water availability is a sensitive control parameter modulating an abiotic jamming-like transition that determines whether the group remains fluidized and therefore collectively motile, (ii) groups self-organize into discrete layers as they travel, (iii) group motility does not require proliferation, rather groups are pulled from the front, and (iv) flow within expanding groups is capable of moving material from the parent colony into the expanding tip of a cellular dendrite with implications for expansion into regions of varying nutrient content. Together, these findings illuminate the physical structure of surface-motile groups and demonstrate that physical properties, like cellular packing fraction and flow, regulate motion from the scale of individual cells up to length scales of centimetres.
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Affiliation(s)
- Ben Rhodeland
- Department of Physics, University of Oregon, Eugene OR 97403, USA
| | - Kentaro Hoeger
- Department of Physics, University of Oregon, Eugene OR 97403, USA
| | - Tristan Ursell
- Department of Physics, University of Oregon, Eugene OR 97403, USA.,Institute of Molecular Biology, University of Oregon, Eugene OR 97403, USA.,Materials Science Institute, University of Oregon, Eugene OR 97403, USA
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50
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A Dual-Mechanism Antibiotic Kills Gram-Negative Bacteria and Avoids Drug Resistance. Cell 2020; 181:1518-1532.e14. [PMID: 32497502 DOI: 10.1016/j.cell.2020.05.005] [Citation(s) in RCA: 176] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 02/24/2020] [Accepted: 05/01/2020] [Indexed: 12/22/2022]
Abstract
The rise of antibiotic resistance and declining discovery of new antibiotics has created a global health crisis. Of particular concern, no new antibiotic classes have been approved for treating Gram-negative pathogens in decades. Here, we characterize a compound, SCH-79797, that kills both Gram-negative and Gram-positive bacteria through a unique dual-targeting mechanism of action (MoA) with undetectably low resistance frequencies. To characterize its MoA, we combined quantitative imaging, proteomic, genetic, metabolomic, and cell-based assays. This pipeline demonstrates that SCH-79797 has two independent cellular targets, folate metabolism and bacterial membrane integrity, and outperforms combination treatments in killing methicillin-resistant Staphylococcus aureus (MRSA) persisters. Building on the molecular core of SCH-79797, we developed a derivative, Irresistin-16, with increased potency and showed its efficacy against Neisseria gonorrhoeae in a mouse vaginal infection model. This promising antibiotic lead suggests that combining multiple MoAs onto a single chemical scaffold may be an underappreciated approach to targeting challenging bacterial pathogens.
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