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Seki Y, Eguchi Y, Taoka A. Influence of protozoan grazing on magnetotactic bacteria on intracellular and extracellular iron content. ENVIRONMENTAL MICROBIOLOGY REPORTS 2023; 15:181-187. [PMID: 36779255 PMCID: PMC10464679 DOI: 10.1111/1758-2229.13140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/28/2022] [Indexed: 05/06/2023]
Abstract
Magnetotactic bacteria (MTB) ubiquitously inhabit the oxic-anoxic interface or anaerobic areas of aquatic environments. MTB biomineralize magnetite or greigite crystals and synthesize an organelle known as magnetosome. This intrinsic ability of MTB allows them to accumulate iron to levels 100-1000 times higher than those in non-magnetotactic bacteria (non-MTB). Therefore, MTB considerably contributes to the global iron cycle as primary iron suppliers in the aquatic environmental food chain. However, to the best of our knowledge, there have been no reports describing the effects of trophic interactions between MTB and their protist grazers on the iron distributions in MTB grazers and the extracellular milieu. Herein, we evaluated the effects of MTB grazing using a model species of protist (Tetrahymena pyriformis) and a model species of MTB (Magnetospirillum magneticum AMB-1). MTB-fed T. pyriformis exhibited a magnetic response and contained magnetite crystals in their vacuoles. Fluorescence imaging using a ferrous ion-specific fluorescent dye revealed that the cellular ferrous ion content was five times higher in MTB-fed T. pyriformis than in non-MTB grazers. Moreover, soluble iron concentrations in the spent media increased with time during MTB predation. This study provides experimental evidence to delineate the importance of trophic interactions of MTB on iron distributions.
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Affiliation(s)
- Yusuke Seki
- Institute of Science and EngineeringKanazawa UniversityKakuma‐machi, KanazawaIshikawaJapan
| | - Yukako Eguchi
- Institute for Promotion of Diversity and InclusionKanazawa UniversityKakuma‐machi, KanazawaIshikawaJapan
| | - Azuma Taoka
- Institute of Science and EngineeringKanazawa UniversityKakuma‐machi, KanazawaIshikawaJapan
- Nano Life Science Institute (WPI‐NanoLSI)Kanazawa UniversityKakuma‐machi, KanazawaIshikawaJapan
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2
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Live-Cell Fluorescence Imaging of Magnetosome Organelle for Magnetotaxis Motility. Methods Mol Biol 2023; 2646:133-146. [PMID: 36842112 DOI: 10.1007/978-1-0716-3060-0_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
The assessment of intracellular dynamics is crucial for understanding the function and formation process of bacterial organelle, just as it is for the inquisition of their eukaryotic counterparts. The methods for imaging magnetosome organelles in a magnetotactic bacterial cell using live-cell fluorescence imaging by highly inclined and laminated optical sheet (HILO) microscopy are presented in this chapter. Furthermore, we introduce methods for pH imaging in magnetosome lumen as an application of fluorescence magnetosome imaging.
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3
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Kikuchi Y, Toyofuku M, Ichinaka Y, Kiyokawa T, Obana N, Nomura N, Taoka A. Physical Properties and Shifting of the Extracellular Membrane Vesicles Attached to Living Bacterial Cell Surfaces. Microbiol Spectr 2022; 10:e0216522. [PMID: 36383005 PMCID: PMC9769862 DOI: 10.1128/spectrum.02165-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 11/02/2022] [Indexed: 11/18/2022] Open
Abstract
Bacterial cells release nanometer-sized extracellular membrane vesicles (MVs) to deliver cargo molecules for use in mediating various biological processes. However, the detailed processes of transporting these cargos from MVs to recipient cells remain unclear because of the lack of imaging techniques to image nanometer-sized fragile vesicles in a living bacterial cell surface. Herein, we quantitatively demonstrated that the direct binding of MV to the cell surface significantly promotes hydrophobic quorum-sensing signal (C16-HSL) transportation to the recipient cells. Moreover, we analyzed the MV-binding process in the Paracoccus denitrificans cell surface using high-speed atomic force microscopy phase imaging. Although MV shapes were unaltered after binding to the cell surface, the physical properties of a group of single MV particles were shifted. Additionally, the phase shift values of MVs were higher than that of the cell's surfaces upon binding, whereas the phase shift values of the group of MVs were decreased during observation. The shifting physical properties occurred irreversibly only once for each MV during the observations. The decreasing phase shift values indicated alterations of chemical components in the MVs as well, thereby suggesting the dynamic process in which single MV particles deliver their hydrophobic cargo into the recipient cell. IMPORTANCE Compared to the increasing knowledge about MV release mechanisms from donor cells, the mechanism by which recipient cells receive cargo from MVs remains unknown. Herein, we have successfully imaged single MV-binding processes in living bacterial cell surfaces. Accordingly, we confirmed the shift in the MV hydrophobic properties after landing on the cell surface. Our results showed the detailed states and the attaching process of a single MV into the cell surface and can aid the development of a new model for MV reception into Gram-negative bacterial cell surfaces. The insight provided by this study is significant for understanding MV-mediated cell-cell communication mechanisms. Moreover, the AFM technique presented for nanometer-scaled mapping of dynamic physical properties alteration on a living cell could be applied for the analyses of various biological phenomena occurring on the cell surface, and it gives us a new view into the understanding of the phenotypes of the bacterial cell surface.
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Affiliation(s)
- Yousuke Kikuchi
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Japan
| | - Masanori Toyofuku
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
- Suntory Rising Stars Encouragement Program in Life Sciences (SunRiSE), Seika, Kyoto, Japan
| | - Yuki Ichinaka
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
| | - Tatsunori Kiyokawa
- Graduate of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Nozomu Obana
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
- Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tennodai, Tsukuba, Japan
| | - Azuma Taoka
- Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa, Japan
- WPI Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, Kakuma, Kanazawa, Japan
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4
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Wan J, Monteil CL, Taoka A, Ernie G, Park K, Amor M, Taylor-Cornejo E, Lefevre CT, Komeili A. McaA and McaB control the dynamic positioning of a bacterial magnetic organelle. Nat Commun 2022; 13:5652. [PMID: 36163114 PMCID: PMC9512821 DOI: 10.1038/s41467-022-32914-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 08/23/2022] [Indexed: 11/17/2022] Open
Abstract
Magnetotactic bacteria are a diverse group of microorganisms that use intracellular chains of ferrimagnetic nanocrystals, produced within magnetosome organelles, to align and navigate along the geomagnetic field. Several conserved genes for magnetosome formation have been described, but the mechanisms leading to distinct species-specific magnetosome chain configurations remain unclear. Here, we show that the fragmented nature of magnetosome chains in Magnetospirillum magneticum AMB-1 is controlled by genes mcaA and mcaB. McaA recognizes the positive curvature of the inner cell membrane, while McaB localizes to magnetosomes. Along with the MamK actin-like cytoskeleton, McaA and McaB create space for addition of new magnetosomes in between pre-existing magnetosomes. Phylogenetic analyses suggest that McaA and McaB homologs are widespread among magnetotactic bacteria and may represent an ancient strategy for magnetosome positioning.
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Affiliation(s)
- Juan Wan
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Caroline L Monteil
- Aix-Marseille Université, CEA, CNRS, Institute of Biosciences and Biotechnologies of Aix-Marseille, 13108, Saint-Paul-lez-Durance, France
| | - Azuma Taoka
- Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Gabriel Ernie
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Kieop Park
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
- Department of Biology, Duke University, Box 90338, Durham, NC, 27708, USA
| | - Matthieu Amor
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
- Aix-Marseille Université, CEA, CNRS, Institute of Biosciences and Biotechnologies of Aix-Marseille, 13108, Saint-Paul-lez-Durance, France
| | - Elias Taylor-Cornejo
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
- Department of Biology, Randolph-Macon College, Ashland, VA, 23005, USA
| | - Christopher T Lefevre
- Aix-Marseille Université, CEA, CNRS, Institute of Biosciences and Biotechnologies of Aix-Marseille, 13108, Saint-Paul-lez-Durance, France
| | - Arash Komeili
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA.
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5
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Chmykhalo V, Belanova A, Belousova M, Butova V, Makarenko Y, Khrenkova V, Soldatov A, Zolotukhin P. Microbial-based magnetic nanoparticles production: a mini-review. Integr Biol (Camb) 2021; 13:98-107. [PMID: 33829272 DOI: 10.1093/intbio/zyab005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 11/14/2022]
Abstract
The ever-increasing biomedical application of magnetic nanoparticles (MNPs) implies increasing demand in their scalable and high-throughput production, with finely tuned and well-controlled characteristics. One of the options to meet the demand is microbial production by nanoparticles-synthesizing bacteria. This approach has several benefits over the standard chemical synthesis methods, including improved homogeneity of synthesis, cost-effectiveness, safety and eco-friendliness. There are, however, specific challenges emanating from the nature of the approach that are to be accounted and resolved in each manufacturing instance. Most of the challenges can be resolved by proper selection of the producing organism and optimizing cell culture and nanoparticles extraction conditions. Other issues require development of proper continuous production equipment, medium usage optimization and precursor ions recycling. This mini-review focuses on the related topics in microbial synthesis of MNPs: producing organisms, culturing methods, nanoparticles characteristics tuning, nanoparticles yield and synthesis timeframe considerations, nanoparticles isolation as well as on the respective challenges and possible solutions.
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Affiliation(s)
- Victor Chmykhalo
- Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, Russia
| | - Anna Belanova
- Smart Materials International Research Centre, Southern Federal University, Rostov-on-Don, Russia
| | - Mariya Belousova
- English Language Department for Natural Sciences Faculties, Southern Federal University, Rostov-on-Don, Russia
| | - Vera Butova
- Smart Materials International Research Centre, Southern Federal University, Rostov-on-Don, Russia
| | | | - Vera Khrenkova
- Medical Consulting Department, Rostov-on-Don Pathological-Anatomical Bureau No. 1, Rostov-on-Don, Russia
| | - Alexander Soldatov
- Smart Materials International Research Centre, Southern Federal University, Rostov-on-Don, Russia
| | - Peter Zolotukhin
- Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, Russia
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6
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Arakaki A, Goto M, Maruyama M, Yoda T, Tanaka M, Yamagishi A, Yoshikuni Y, Matsunaga T. Restoration and Modification of Magnetosome Biosynthesis by Internal Gene Acquisition in a Magnetotactic Bacterium. Biotechnol J 2020; 15:e2000278. [DOI: 10.1002/biot.202000278] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/02/2020] [Indexed: 02/02/2023]
Affiliation(s)
- Atsushi Arakaki
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
| | - Mayu Goto
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
| | - Mina Maruyama
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
| | - Takuto Yoda
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
| | - Masayoshi Tanaka
- Department of Chemical Science and Engineering Tokyo Institute of Technology 2‐12‐1 O‐okayama Meguro‐ku Tokyo 152‐8550 Japan
| | - Ayana Yamagishi
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
| | - Yasuo Yoshikuni
- DNA Synthesis Science Program Lawrence Berkeley National Laboratory The U.S. Department of Energy Joint Genome Institute Berkeley CA 94720 USA
| | - Tadashi Matsunaga
- Division of Biotechnology and Life Science Institute of Engineering Tokyo University of Agriculture and Technology 2‐24‐16 Naka‐cho Koganei Tokyo 184‐8588 Japan
- Japan Agency for Marine‐Earth Science and Technology (JAMSTEC) 2‐15, Natsushima‐cho Yokosuka Kanagawa 237‐0061 Japan
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7
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Greening C, Lithgow T. Formation and function of bacterial organelles. Nat Rev Microbiol 2020; 18:677-689. [PMID: 32710089 DOI: 10.1038/s41579-020-0413-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2020] [Indexed: 01/28/2023]
Abstract
Advances in imaging technologies have revealed that many bacteria possess organelles with a proteomically defined lumen and a macromolecular boundary. Some are bound by a lipid bilayer (such as thylakoids, magnetosomes and anammoxosomes), whereas others are defined by a lipid monolayer (such as lipid bodies), a proteinaceous coat (such as carboxysomes) or have a phase-defined boundary (such as nucleolus-like compartments). These diverse organelles have various metabolic and physiological functions, facilitating adaptation to different environments and driving the evolution of cellular complexity. This Review highlights that, despite the diversity of reported organelles, some unifying concepts underlie their formation, structure and function. Bacteria have fundamental mechanisms of organelle formation, through which conserved processes can form distinct organelles in different species depending on the proteins recruited to the luminal space and the boundary of the organelle. These complex subcellular compartments provide evolutionary advantages as well as enabling metabolic specialization, biogeochemical processes and biotechnological advances. Growing evidence suggests that the presence of organelles is the rule, rather than the exception, in bacterial cells.
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Affiliation(s)
- Chris Greening
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Australia.
| | - Trevor Lithgow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Australia.
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8
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Abstract
Many species of bacteria can manufacture materials on a finer scale than those that are synthetically made. These products are often produced within intracellular compartments that bear many hallmarks of eukaryotic organelles. One unique and elegant group of organisms is at the forefront of studies into the mechanisms of organelle formation and biomineralization. Magnetotactic bacteria (MTB) produce organelles called magnetosomes that contain nanocrystals of magnetic material, and understanding the molecular mechanisms behind magnetosome formation and biomineralization is a rich area of study. In this Review, we focus on the genetics behind the formation of magnetosomes and biomineralization. We cover the history of genetic discoveries in MTB and key insights that have been found in recent years and provide a perspective on the future of genetic studies in MTB.
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Affiliation(s)
- Hayley C. McCausland
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Arash Komeili
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
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9
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Dieudonné A, Pignol D, Prévéral S. Magnetosomes: biogenic iron nanoparticles produced by environmental bacteria. Appl Microbiol Biotechnol 2019; 103:3637-3649. [PMID: 30903215 DOI: 10.1007/s00253-019-09728-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/22/2019] [Accepted: 02/25/2019] [Indexed: 01/10/2023]
Abstract
The scientific community's interest in magnetotactic bacteria has increased substantially in recent decades. These prokaryotes have the particularity of synthesizing nanomagnets, called magnetosomes. The majority of research is based on several scientific questions. Where do magnetotactic bacteria live, what are their characteristics, and why are they magnetic? What are the molecular phenomena of magnetosome biomineralization and what are the physical characteristics of magnetosomes? In addition to scientific curiosity to better understand these stunning organisms, there are biotechnological opportunities to consider. Magnetotactic bacteria, as well as magnetosomes, are used in medical applications, for example cancer treatment, or in environmental ones, for example bioremediation. In this mini-review, we investigated all the aspects mentioned above and summarized the currently available knowledge.
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Affiliation(s)
- Anissa Dieudonné
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France
| | - David Pignol
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France
| | - Sandra Prévéral
- UMR 7265, Aix Marseille Univ, CEA, CNRS, BIAM, LBC, Saint Paul-Lez-Durance, France.
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10
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Abstract
Uncovering the mechanisms that underlie the biogenesis and maintenance of eukaryotic organelles is a vibrant and essential area of biological research. In comparison, little attention has been paid to the process of compartmentalization in bacteria and archaea. This lack of attention is in part due to the common misconception that organelles are a unique evolutionary invention of the "complex" eukaryotic cell and are absent from the "primitive" bacterial and archaeal cells. Comparisons across the tree of life are further complicated by the nebulous criteria used to designate subcellular structures as organelles. Here, with the aid of a unified definition of a membrane-bounded organelle, we present some of the recent findings in the study of lipid-bounded organelles in bacteria and archaea.
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Affiliation(s)
- Carly R Grant
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA;
| | - Juan Wan
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA;
| | - Arash Komeili
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA;
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11
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LaSarre B, Kysela DT, Stein BD, Ducret A, Brun YV, McKinlay JB. Restricted Localization of Photosynthetic Intracytoplasmic Membranes (ICMs) in Multiple Genera of Purple Nonsulfur Bacteria. mBio 2018; 9:e00780-18. [PMID: 29970460 PMCID: PMC6030561 DOI: 10.1128/mbio.00780-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/06/2018] [Indexed: 01/18/2023] Open
Abstract
In bacteria and eukaryotes alike, proper cellular physiology relies on robust subcellular organization. For the phototrophic purple nonsulfur bacteria (PNSB), this organization entails the use of a light-harvesting, membrane-bound compartment known as the intracytoplasmic membrane (ICM). Here we show that ICMs are spatially and temporally localized in diverse patterns among PNSB. We visualized ICMs in live cells of 14 PNSB species across nine genera by exploiting the natural autofluorescence of the photosynthetic pigment bacteriochlorophyll (BChl). We then quantitatively characterized ICM localization using automated computational analysis of BChl fluorescence patterns within single cells across the population. We revealed that while many PNSB elaborate ICMs along the entirety of the cell, species across as least two genera restrict ICMs to discrete, nonrandom sites near cell poles in a manner coordinated with cell growth and division. Phylogenetic and phenotypic comparisons established that ICM localization and ICM architecture are not strictly interdependent and that neither trait fully correlates with the evolutionary relatedness of the species. The natural diversity of ICM localization revealed herein has implications for both the evolution of phototrophic organisms and their light-harvesting compartments and the mechanisms underpinning spatial organization of bacterial compartments.IMPORTANCE Many bacteria organize their cellular space by constructing subcellular compartments that are arranged in specific, physiologically relevant patterns. The purple nonsulfur bacteria (PNSB) utilize a membrane-bound compartment known as the intracytoplasmic membrane (ICM) to harvest light for photosynthesis. It was previously unknown whether ICM localization within cells is systematic or irregular and if ICM localization is conserved among PNSB. Here we surveyed ICM localization in diverse PNSB and show that ICMs are spatially organized in species-specific patterns. Most strikingly, several PNSB resolutely restrict ICMs to regions near the cell poles, leaving much of the cell devoid of light-harvesting machinery. Our results demonstrate that bacteria of a common lifestyle utilize unequal portions of their intracellular space to harvest light, despite light harvesting being a process that is intuitively influenced by surface area. Our findings therefore raise fundamental questions about ICM biology and evolution.
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Affiliation(s)
- Breah LaSarre
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - David T Kysela
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Barry D Stein
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Adrien Ducret
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - James B McKinlay
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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12
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Eguchi Y, Fukumori Y, Taoka A. Measuring magnetosomal pH of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 using pH-sensitive fluorescent proteins. Biosci Biotechnol Biochem 2018; 82:1243-1251. [PMID: 29557302 DOI: 10.1080/09168451.2018.1451739] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Magnetotactic bacteria synthesize uniform-sized and regularly shaped magnetic nanoparticles in their organelles termed magnetosomes. Homeostasis of the magnetosome lumen must be maintained for its role accomplishment. Here, we developed a method to estimate the pH of a single living cell of the magnetotactic bacterium Magnetospirillum magneticum AMB-1 using a pH-sensitive fluorescent protein E2GFP. Using the pH measurement, we estimated that the cytoplasmic pH was approximately 7.6 and periplasmic pH was approximately 7.2. Moreover, we estimated pH in the magnetosome lumen and cytoplasmic surface using fusion proteins of E2GFP and magnetosome-associated proteins. The pH in the magnetosome lumen increased during the exponential growth phase when magnetotactic bacteria actively synthesize magnetite crystals, whereas pH at the magnetosome surface was not affected by the growth stage. This live-cell pH measurement method will help for understanding magnetosome pH homeostasis to reveal molecular mechanisms of magnetite biomineralization in the bacterial organelle.
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Affiliation(s)
- Yukako Eguchi
- a Department of Life Science, Graduate School of Natural Science and Technology , Kanazawa University , Kanazawa , Japan
| | - Yoshihiro Fukumori
- b Faculty of Natural System, Institute of Science and Engineering , Kanazawa University , Kanazawa , Japan
| | - Azuma Taoka
- b Faculty of Natural System, Institute of Science and Engineering , Kanazawa University , Kanazawa , Japan.,c Bio-AFM Frontier Research Center, College of Science and Engineering , Kanazawa University , Kanazawa , Japan
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