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Bru JL, Kasallis SJ, Zhuo Q, Høyland-Kroghsbo NM, Siryaporn A. Swarming of P. aeruginosa: Through the lens of biophysics. BIOPHYSICS REVIEWS 2023; 4:031305. [PMID: 37781002 PMCID: PMC10540860 DOI: 10.1063/5.0128140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 08/29/2023] [Indexed: 10/03/2023]
Abstract
Swarming is a collective flagella-dependent movement of bacteria across a surface that is observed across many species of bacteria. Due to the prevalence and diversity of this motility modality, multiple models of swarming have been proposed, but a consensus on a general mechanism for swarming is still lacking. Here, we focus on swarming by Pseudomonas aeruginosa due to the abundance of experimental data and multiple models for this species, including interpretations that are rooted in biology and biophysics. In this review, we address three outstanding questions about P. aeruginosa swarming: what drives the outward expansion of a swarm, what causes the formation of dendritic patterns (tendrils), and what are the roles of flagella? We review models that propose biologically active mechanisms including surfactant sensing as well as fluid mechanics-based models that consider swarms as thin liquid films. Finally, we reconcile recent observations of P. aeruginosa swarms with early definitions of swarming. This analysis suggests that mechanisms associated with sliding motility have a critical role in P. aeruginosa swarm formation.
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Affiliation(s)
- Jean-Louis Bru
- Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, California 92697, USA
| | - Summer J. Kasallis
- Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, USA
| | - Quantum Zhuo
- Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, USA
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2
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Miyata M, Robinson RC, Uyeda TQP, Fukumori Y, Fukushima SI, Haruta S, Homma M, Inaba K, Ito M, Kaito C, Kato K, Kenri T, Kinosita Y, Kojima S, Minamino T, Mori H, Nakamura S, Nakane D, Nakayama K, Nishiyama M, Shibata S, Shimabukuro K, Tamakoshi M, Taoka A, Tashiro Y, Tulum I, Wada H, Wakabayashi KI. Tree of motility - A proposed history of motility systems in the tree of life. Genes Cells 2020; 25:6-21. [PMID: 31957229 PMCID: PMC7004002 DOI: 10.1111/gtc.12737] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/11/2019] [Accepted: 11/17/2019] [Indexed: 12/27/2022]
Abstract
Motility often plays a decisive role in the survival of species. Five systems of motility have been studied in depth: those propelled by bacterial flagella, eukaryotic actin polymerization and the eukaryotic motor proteins myosin, kinesin and dynein. However, many organisms exhibit surprisingly diverse motilities, and advances in genomics, molecular biology and imaging have showed that those motilities have inherently independent mechanisms. This makes defining the breadth of motility nontrivial, because novel motilities may be driven by unknown mechanisms. Here, we classify the known motilities based on the unique classes of movement‐producing protein architectures. Based on this criterion, the current total of independent motility systems stands at 18 types. In this perspective, we discuss these modes of motility relative to the latest phylogenetic Tree of Life and propose a history of motility. During the ~4 billion years since the emergence of life, motility arose in Bacteria with flagella and pili, and in Archaea with archaella. Newer modes of motility became possible in Eukarya with changes to the cell envelope. Presence or absence of a peptidoglycan layer, the acquisition of robust membrane dynamics, the enlargement of cells and environmental opportunities likely provided the context for the (co)evolution of novel types of motility.
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Affiliation(s)
- Makoto Miyata
- Department of Biology, Graduate School of Science, Osaka City University, Osaka, Japan.,The OCU Advanced Research Institute for Natural Science and Technology (OCARINA), Osaka City University, Osaka, Japan
| | - Robert C Robinson
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan.,School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Taro Q P Uyeda
- Department of Physics, Faculty of Science and Technology, Waseda University, Tokyo, Japan
| | - Yoshihiro Fukumori
- Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan.,WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Shun-Ichi Fukushima
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, Japan
| | - Shin Haruta
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Kazuo Inaba
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
| | - Masahiro Ito
- Graduate School of Life Sciences, Toyo University, Gunma, Japan
| | - Chikara Kaito
- Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kentaro Kato
- Laboratory of Sustainable Animal Environment, Graduate School of Agricultural Science, Tohoku University, Miyagi, Japan
| | - Tsuyoshi Kenri
- Laboratory of Mycoplasmas and Haemophilus, Department of Bacteriology II, National Institute of Infectious Diseases, Tokyo, Japan
| | | | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Hiroyuki Mori
- Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Shuichi Nakamura
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Miyagi, Japan
| | - Daisuke Nakane
- Department of Physics, Gakushuin University, Tokyo, Japan
| | - Koji Nakayama
- Department of Microbiology and Oral Infection, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Masayoshi Nishiyama
- Department of Physics, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Satoshi Shibata
- Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Katsuya Shimabukuro
- Department of Chemical and Biological Engineering, National Institute of Technology, Ube College, Yamaguchi, Japan
| | - Masatada Tamakoshi
- Department of Molecular Biology, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Azuma Taoka
- Faculty of Natural System, Institute of Science and Engineering, Kanazawa University, Kanazawa, Japan.,WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan
| | - Yosuke Tashiro
- Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
| | - Isil Tulum
- Department of Botany, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Hirofumi Wada
- Department of Physics, Graduate School of Science and Engineering, Ritsumeikan University, Shiga, Japan
| | - Ken-Ichi Wakabayashi
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Kanagawa, Japan
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3
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Yan J, Monaco H, Xavier JB. The Ultimate Guide to Bacterial Swarming: An Experimental Model to Study the Evolution of Cooperative Behavior. Annu Rev Microbiol 2019; 73:293-312. [PMID: 31180806 PMCID: PMC7428860 DOI: 10.1146/annurev-micro-020518-120033] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Cooperation has fascinated biologists since Darwin. How did cooperative behaviors evolve despite the fitness cost to the cooperator? Bacteria have cooperative behaviors that make excellent models to take on this age-old problem from both proximate (molecular) and ultimate (evolutionary) angles. We delve into Pseudomonas aeruginosa swarming, a phenomenon where billions of bacteria move cooperatively across distances of centimeters in a matter of a few hours. Experiments with swarming have unveiled a strategy called metabolic prudence that stabilizes cooperation, have showed the importance of spatial structure, and have revealed a regulatory network that integrates environmental stimuli and direct cooperative behavior, similar to a machine learning algorithm. The study of swarming elucidates more than proximate mechanisms: It exposes ultimate mechanisms valid to all scales, from cells in cancerous tumors to animals in large communities.
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Affiliation(s)
- Jinyuan Yan
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA;
| | - Hilary Monaco
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA;
| | - Joao B Xavier
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA;
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Dragoš A, Kiesewalter H, Martin M, Hsu CY, Hartmann R, Wechsler T, Eriksen C, Brix S, Drescher K, Stanley-Wall N, Kümmerli R, Kovács ÁT. Division of Labor during Biofilm Matrix Production. Curr Biol 2018; 28:1903-1913.e5. [PMID: 29887307 DOI: 10.1016/j.cub.2018.04.046] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 03/13/2018] [Accepted: 04/13/2018] [Indexed: 01/06/2023]
Abstract
Organisms as simple as bacteria can engage in complex collective actions, such as group motility and fruiting body formation. Some of these actions involve a division of labor, where phenotypically specialized clonal subpopulations or genetically distinct lineages cooperate with each other by performing complementary tasks. Here, we combine experimental and computational approaches to investigate potential benefits arising from division of labor during biofilm matrix production. We show that both phenotypic and genetic strategies for a division of labor can promote collective biofilm formation in the soil bacterium Bacillus subtilis. In this species, biofilm matrix consists of two major components, exopolysaccharides (EPSs) and TasA. We observed that clonal groups of B. subtilis phenotypically segregate into three subpopulations composed of matrix non-producers, EPS producers, and generalists, which produce both EPSs and TasA. This incomplete phenotypic specialization was outperformed by a genetic division of labor, where two mutants, engineered as specialists, complemented each other by exchanging EPSs and TasA. The relative fitness of the two mutants displayed a negative frequency dependence both in vitro and on plant roots, with strain frequency reaching a stable equilibrium at 30% TasA producers, corresponding exactly to the population composition where group productivity is maximized. Using individual-based modeling, we show that asymmetries in strain ratio can arise due to differences in the relative benefits that matrix compounds generate for the collective and that genetic division of labor can be favored when it breaks metabolic constraints associated with the simultaneous production of two matrix components.
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Affiliation(s)
- Anna Dragoš
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark; Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany
| | - Heiko Kiesewalter
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark
| | - Marivic Martin
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark; Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany
| | - Chih-Yu Hsu
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Raimo Hartmann
- Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Tobias Wechsler
- Department of Plant and Microbial Biology, University of Zürich, Zürich 8057, Switzerland
| | - Carsten Eriksen
- Disease Systems Immunology Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark
| | - Susanne Brix
- Disease Systems Immunology Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany; Department of Physics, Philipps University, Marburg 35037, Germany
| | | | - Rolf Kümmerli
- Department of Plant and Microbial Biology, University of Zürich, Zürich 8057, Switzerland
| | - Ákos T Kovács
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs Lyngby 2800, Denmark; Terrestrial Biofilms Group, Institute of Microbiology, Friedrich Schiller University Jena, Jena 07743, Germany.
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5
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Yan J, Deforet M, Boyle KE, Rahman R, Liang R, Okegbe C, Dietrich LEP, Qiu W, Xavier JB. Bow-tie signaling in c-di-GMP: Machine learning in a simple biochemical network. PLoS Comput Biol 2017; 13:e1005677. [PMID: 28767643 PMCID: PMC5555705 DOI: 10.1371/journal.pcbi.1005677] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/14/2017] [Accepted: 07/10/2017] [Indexed: 11/18/2022] Open
Abstract
Bacteria of many species rely on a simple molecule, the intracellular secondary messenger c-di-GMP (Bis-(3'-5')-cyclic dimeric guanosine monophosphate), to make a vital choice: whether to stay in one place and form a biofilm, or to leave it in search of better conditions. The c-di-GMP network has a bow-tie shaped architecture that integrates many signals from the outside world—the input stimuli—into intracellular c-di-GMP levels that then regulate genes for biofilm formation or for swarming motility—the output phenotypes. How does the ‘uninformed’ process of evolution produce a network with the right input/output association and enable bacteria to make the right choice? Inspired by new data from 28 clinical isolates of Pseudomonas aeruginosa and strains evolved in laboratory experiments we propose a mathematical model where the c-di-GMP network is analogous to a machine learning classifier. The analogy immediately suggests a mechanism for learning through evolution: adaptation though incremental changes in c-di-GMP network proteins acquires knowledge from past experiences and enables bacteria to use it to direct future behaviors. Our model clarifies the elusive function of the ubiquitous c-di-GMP network, a key regulator of bacterial social traits associated with virulence. More broadly, the link between evolution and machine learning can help explain how natural selection across fluctuating environments produces networks that enable living organisms to make sophisticated decisions. How does evolution shape living organisms that seem so well adapted that they could be intelligently designed? Here, we address this question by analyzing a simple biochemical network that directs social behavior in bacteria; we find that it works analogously to a machine learning algorithm that learns from data. Inspired by new experiments, we derive a model which shows that natural selection—by favoring biochemical networks that maximize fitness across a series of fluctuating environments—can be mathematically equivalent to training a machine learning model to solve a classification problem. Beyond bacteria, the formal link between evolution and learning opens new avenues for biology: machine learning is a fast-moving field and its many theoretical breakthroughs can answer long-standing questions in evolution.
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Affiliation(s)
- Jinyuan Yan
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States of America
| | - Maxime Deforet
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States of America
| | - Kerry E. Boyle
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States of America
| | - Rayees Rahman
- Department of Biological Sciences, Hunter College & Graduate Center, CUNY, New York, NY, United States of America
| | - Raymond Liang
- Department of Biological Sciences, Hunter College & Graduate Center, CUNY, New York, NY, United States of America
| | - Chinweike Okegbe
- Department of Biological Sciences, Columbia University, New York, NY, United States of America
| | - Lars E. P. Dietrich
- Department of Biological Sciences, Columbia University, New York, NY, United States of America
| | - Weigang Qiu
- Department of Biological Sciences, Hunter College & Graduate Center, CUNY, New York, NY, United States of America
| | - Joao B. Xavier
- Program for Computational and Systems Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, United States of America
- * E-mail:
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6
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Rendueles O, Velicer GJ. Evolution by flight and fight: diverse mechanisms of adaptation by actively motile microbes. ISME JOURNAL 2016; 11:555-568. [PMID: 27662568 PMCID: PMC5270557 DOI: 10.1038/ismej.2016.115] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 06/19/2016] [Accepted: 07/03/2016] [Indexed: 01/16/2023]
Abstract
Evolutionary adaptation can be achieved by mechanisms accessible to all organisms, including faster growth and interference competition, but self-generated motility offers additional possibilities. We tested whether 55 populations of the bacterium Myxococcus xanthus that underwent selection for increased fitness at the leading edge of swarming colonies adapted by swarming faster toward unused resources or by other means. Populations adapted greatly but diversified markedly in both swarming phenotypes and apparent mechanisms of adaptation. Intriguingly, although many adapted populations swarm intrinsically faster than their ancestors, numerous others do not. Some populations evolved interference competition toward their ancestors, whereas others gained the ability to facultatively increase swarming rate specifically upon direct interaction with ancestral competitors. Our results both highlight the diverse range of mechanisms by which actively motile organisms can adapt evolutionarily and help to explain the high levels of swarming-phenotype diversity found in local soil populations of M. xanthus.
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Affiliation(s)
- Olaya Rendueles
- Institute for Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich, Switzerland
| | - Gregory J Velicer
- Institute for Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich, Switzerland
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7
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Xavier JB. Sociomicrobiology and Pathogenic Bacteria. Microbiol Spectr 2016; 4:10.1128/microbiolspec.VMBF-0019-2015. [PMID: 27337482 PMCID: PMC4920084 DOI: 10.1128/microbiolspec.vmbf-0019-2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Indexed: 12/16/2022] Open
Abstract
The study of microbial pathogenesis has been primarily a reductionist science since Koch's principles. Reductionist approaches are essential to identify the causal agents of infectious disease, their molecular mechanisms of action, and potential drug targets, and much of medicine's success in the treatment of infectious disease stems from that approach. But many bacteria-caused diseases cannot be explained by a single bacterium. Several aspects of bacterial pathogenesis will benefit from a more holistic approach that takes into account social interaction among bacteria of the same species and between species in consortia such as the human microbiome. The emerging discipline of sociomicrobiology provides a framework to dissect microbial interactions in single and multi-species communities without compromising mechanistic detail. The study of bacterial pathogenesis can benefit greatly from incorporating concepts from other disciplines such as social evolution theory and microbial ecology, where communities, their interactions with hosts, and with the environment play key roles.
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Affiliation(s)
- Joao B. Xavier
- Program for Computational Biology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, Box 460, New York, NY 10065,
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8
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Räz MH, Hollenstein M. Probing the effect of minor groove interactions on the catalytic efficiency of DNAzymes 8-17 and 10-23. MOLECULAR BIOSYSTEMS 2016; 11:1454-61. [PMID: 25854917 DOI: 10.1039/c5mb00102a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
DNAzymes (Dz) 8-17 and 10-23 are two widely studied and well-characterized RNA-cleaving DNA catalysts. In an effort to further improve the understanding of the fragile interactions and dynamics of the enzymatic mechanism, this study examines the catalytic efficiency of minimally modified DNAzymes. Five single mutants of Dz8-17 and Dz10-23 were prepared by replacing the adenine residues in the corresponding catalytic cores with 3-deazaadenine units. Kinetic assays were used to assess the effect on the catalytic activity and thereby identify the importance of hydrogen bonding that arises from the N3 atoms. The results suggest that modifications at A15 and A15.0 of Dz8-17 have a significant influence and show a reduction in catalytic activity. Modification at each location in Dz10-23 results in a decrease of the observed rate constants, with A12 appearing to be the most affected with a reduction of ∼80% of kobs and ∼25% of the maximal cleavage rate compared to the wild-type DNAzyme. On the other hand, modification of A12 in Dz8-17 showed an ∼130% increase in kobs, thus unraveling a new potential site for the introduction of chemical modifications. A pH-profile analysis showed that the chemical cleavage step is rate-determining, regardless of the presence and/or location of the mutation. These findings point towards the importance of the N3-nitrogens of certain adenine nucleotides located within the catalytic cores of the DNAzymes for efficient catalytic activity and further suggest that they might directly partake in maintaining the appropriate tertiary structure. Therefore, it appears that minor groove interactions constitute an important feature of DNAzymes as well as ribozymes.
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Affiliation(s)
- Michael H Räz
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
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Ke WJ, Hsueh YH, Cheng YC, Wu CC, Liu ST. Water surface tension modulates the swarming mechanics of Bacillus subtilis. Front Microbiol 2015; 6:1017. [PMID: 26557106 PMCID: PMC4616241 DOI: 10.3389/fmicb.2015.01017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/08/2015] [Indexed: 12/02/2022] Open
Abstract
Many Bacillus subtilis strains swarm, often forming colonies with tendrils on agar medium. It is known that B. subtilis swarming requires flagella and a biosurfactant, surfactin. In this study, we find that water surface tension plays a role in swarming dynamics. B. subtilis colonies were found to contain water, and when a low amount of surfactin is produced, the water surface tension of the colony restricts expansion, causing bacterial density to rise. The increased density induces a quorum sensing response that leads to heightened production of surfactin, which then weakens water surface tension to allow colony expansion. When the barrier formed by water surface tension is breached at a specific location, a stream of bacteria swarms out of the colony to form a tendril. If a B. subtilis strain produces surfactin at levels that can substantially weaken the overall water surface tension of the colony, water floods the agar surface in a thin layer, within which bacteria swarm and migrate rapidly. This study sheds light on the role of water surface tension in regulating B. subtilis swarming, and provides insight into the mechanisms underlying swarming initiation and tendril formation.
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Affiliation(s)
- Wan-Ju Ke
- Department of Microbiology and Immunology, Chang Gung University Taoyuan, Taiwan ; Research Center for Bacterial Pathogenesis, Chang Gung University Taoyuan, Taiwan
| | - Yi-Huang Hsueh
- Graduate School of Biotechnology and Bioengineering, Yuan Ze University Taoyuan, Taiwan
| | - Yu-Chieh Cheng
- Department of Microbiology and Immunology, Chang Gung University Taoyuan, Taiwan
| | - Chih-Ching Wu
- Department of Medical Biotechnology and Laboratory Science Proteomic Center, College of Medicine, Chang Gung University Taoyuan, Taiwan
| | - Shih-Tung Liu
- Department of Microbiology and Immunology, Chang Gung University Taoyuan, Taiwan ; Department of Medical Research and Development, Chang Gung Memorial Hospital Chiayi Branch Chiayi, Taiwan
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10
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van Ditmarsch D, Xavier JB. Seeing is believing: what experiments with microbes reveal about evolution. Trends Microbiol 2014; 22:2-4. [PMID: 24384383 DOI: 10.1016/j.tim.2013.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 12/20/2022]
Abstract
Darwin's theory of natural selection is among the most powerful ideas in science, yet evolutionary ideas remain challenged to this day. This is in part because evolution often cannot be directly observed. Simple experiments with microbes can change that by enabling direct observation of evolutionary processes.
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Affiliation(s)
- Dave van Ditmarsch
- Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Joao B Xavier
- Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
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11
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Deforet M, van Ditmarsch D, Carmona-Fontaine C, Xavier JB. Hyperswarming adaptations in a bacterium improve collective motility without enhancing single cell motility. SOFT MATTER 2014; 10:2405-13. [PMID: 24622509 PMCID: PMC3955847 DOI: 10.1039/c3sm53127a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pseudomonas aeruginosa is a monoflagellated bacterium that can use its single polar flagellum to swim through liquids and move collectively over semisolid surfaces, a behavior called swarming. Previous studies have shown that experimental evolution in swarming colonies leads to the selection of hyperswarming bacteria with multiple flagella. Here we show that the advantage of such hyperswarmer mutants cannot be explained simply by an increase in the raw swimming speed of individual bacteria in liquids. Cell tracking of time-lapse microscopy to quantify single-cell swimming patterns reveals that both wild-type and hyperswarmers alternate between forward and backward runs, rather than doing the run-and-tumble characteristic of enteric bacteria such as E. coli. High-throughput measurement of swimming speeds reveals that hyperswarmers do not swim faster than wild-type in liquid. Wild-type reverses swimming direction in sharp turns without a significant impact on its speed, whereas multiflagellated hyperswarmers tend to alternate fast and slow runs and have wider turning angles. Nonetheless, macroscopic measurement of swimming and swarming speed in colonies shows that hyperswarmers expand faster than wild-type on surfaces and through soft agar matrices. A mathematical model explains how wider turning angles lead to faster spreading when swimming through agar. Our study describes for the first time the swimming patterns in multiflagellated P. aeruginosa mutants and reveals that collective and individual motility in bacteria are not necessarily correlated. Understanding bacterial adaptations to surface motility, such as hyperswarming, requires a collective behavior approach.
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Affiliation(s)
- Maxime Deforet
- Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
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