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Li SA, Meng XY, Zhang YJ, Chen CL, Jiao YX, Zhu YQ, Liu PP, Sun W. Progress in pH-Sensitive sensors: essential tools for organelle pH detection, spotlighting mitochondrion and diverse applications. Front Pharmacol 2024; 14:1339518. [PMID: 38269286 PMCID: PMC10806205 DOI: 10.3389/fphar.2023.1339518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 12/20/2023] [Indexed: 01/26/2024] Open
Abstract
pH-sensitive fluorescent proteins have revolutionized the field of cellular imaging and physiology, offering insight into the dynamic pH changes that underlie fundamental cellular processes. This comprehensive review explores the diverse applications and recent advances in the use of pH-sensitive fluorescent proteins. These remarkable tools enable researchers to visualize and monitor pH variations within subcellular compartments, especially mitochondria, shedding light on organelle-specific pH regulation. They play pivotal roles in visualizing exocytosis and endocytosis events in synaptic transmission, monitoring cell death and apoptosis, and understanding drug effects and disease progression. Recent advancements have led to improved photostability, pH specificity, and subcellular targeting, enhancing their utility. Techniques for multiplexed imaging, three-dimensional visualization, and super-resolution microscopy are expanding the horizon of pH-sensitive protein applications. The future holds promise for their integration into optogenetics and drug discovery. With their ever-evolving capabilities, pH-sensitive fluorescent proteins remain indispensable tools for unravelling cellular dynamics and driving breakthroughs in biological research. This review serves as a comprehensive resource for researchers seeking to harness the potential of pH-sensitive fluorescent proteins.
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Affiliation(s)
- Shu-Ang Li
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xiao-Yan Meng
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ying-Jie Zhang
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Cai-Li Chen
- Department of Immunology, School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan, China
| | - Yu-Xue Jiao
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yong-Qing Zhu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- The Academy of Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Pei-Pei Liu
- Clinical Systems Biology Laboratories, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Wei Sun
- Department of Burn and Repair Reconstruction, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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2
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Knoblauch J, Waadt R, Cousins AB, Kunz HH. Probing the in situ volumes of Arabidopsis leaf plastids using three-dimensional confocal and scanning electron microscopy. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:332-341. [PMID: 37985241 DOI: 10.1111/tpj.16554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/31/2023] [Accepted: 11/08/2023] [Indexed: 11/22/2023]
Abstract
Leaf plastids harbor a plethora of biochemical reactions including photosynthesis, one of the most important metabolic pathways on Earth. Scientists are eager to unveil the physiological processes within the organelle but also their interconnection with the rest of the plant cell. An increasingly important feature of this venture is to use experimental data in the design of metabolic models. A remaining obstacle has been the limited in situ volume information of plastids and other cell organelles. To fill this gap for chloroplasts, we established three microscopy protocols delivering in situ volumes based on: (i) chlorophyll fluorescence emerging from the thylakoid membrane, (ii) a CFP marker embedded in the envelope, and (iii) calculations from serial block-face scanning electron microscopy (SBFSEM). The obtained data were corroborated by comparing wild-type data with two mutant lines affected in the plastid division machinery known to produce small and large mesophyll chloroplasts, respectively. Furthermore, we also determined the volume of the much smaller guard cell plastids. Interestingly, their volume is not governed by the same components of the division machinery which defines mesophyll plastid size. Based on our three approaches, the average volume of a mature Col-0 wild-type mesophyll chloroplasts is 93 μm3 . Wild-type guard cell plastids are approximately 18 μm3 . Lastly, our comparative analysis shows that the chlorophyll fluorescence analysis can accurately determine chloroplast volumes, providing an important tool to research groups without access to transgenic marker lines expressing genetically encoded fluorescence proteins or costly SBFSEM equipment.
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Affiliation(s)
- Jan Knoblauch
- School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington, 99164-4236, USA
| | - Rainer Waadt
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 7, 48149, Münster, Germany
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington, 99164-4236, USA
| | - Hans-Henning Kunz
- School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, Washington, 99164-4236, USA
- LMU Munich, Plant Biochemistry, Großhadernerstr. 2-4, 82152, Planegg-Martinsried, Germany
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3
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Strobl F, Ratke J, Krämer F, Utta A, Becker S, Stelzer EHK. Next generation marker-based vector concepts for rapid and unambiguous identification of single and double homozygous transgenic organisms. Biol Open 2023; 12:bio060015. [PMID: 37855381 PMCID: PMC10602009 DOI: 10.1242/bio.060015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 08/15/2023] [Indexed: 10/20/2023] Open
Abstract
For diploid model organisms, the actual transgenesis processes require subsequent periods of transgene management, which are challenging in emerging model organisms due to the lack of suitable methodology. We used the red flour beetle Tribolium castaneum, a stored-grain pest, to perform a comprehensive functional evaluation of our AClashOfStrings (ACOS) and the combined AGameOfClones/AClashOfStrings (AGOC/ACOS) vector concepts, which use four clearly distinguishable markers to provide full visual control over up to two independent transgenes. We achieved comprehensive statistical validation of our approach by systematically creating seventeen novel single and double homozygous sublines intended for fluorescence live imaging, including several sublines in which the microtubule cytoskeleton is labeled. During the mating procedures, we genotyped more than 20,000 individuals in less than 80 working hours, which corresponds to about 10 to 15 s per individual. We also confirm the functionality of our combined concept in two double transgene special cases, i.e. integration of both transgenes in close proximity on the same chromosome and integration of one transgene on the X allosome. Finally, we discuss our vector concepts regarding performance, genotyping accuracy, throughput, resource saving potential, fluorescent protein choice, modularity, adaptation to other diploid model organisms and expansion capability.
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Affiliation(s)
- Frederic Strobl
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
| | - Julia Ratke
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
| | - Franziska Krämer
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
| | - Ana Utta
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
| | - Sigrun Becker
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
| | - Ernst H. K. Stelzer
- Physical Biology / Physikalische Biologie (IZN, FB 15), Buchmann Institute for Molecular Life Sciences (BMLS), Cluster of Excellence Frankfurt – Macromolecular Complexes (CEF – MC), Goethe-Universität Frankfurt am Main (Campus Riedberg),Max-von-Laue-Straße 15, D-60438 Frankfurt am Main, Germany
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4
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Zaver SA, Johnson CJ, Berndt A, Simpson CL. Live Imaging with Genetically Encoded Physiologic Sensors and Optogenetic Tools. J Invest Dermatol 2023; 143:353-361.e4. [PMID: 36822769 PMCID: PMC9972253 DOI: 10.1016/j.jid.2022.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/03/2022] [Accepted: 12/04/2022] [Indexed: 02/24/2023]
Abstract
Barrier tissues such as the epidermis employ complex signal transduction systems to execute morphogenetic programs and to rapidly respond to environmental cues to promote homeostasis. Recent advances in live-imaging techniques and tools allow precise spatial and temporal monitoring and manipulation of intracellular signaling cascades. Leveraging the chemistry of naturally occurring light-sensitive proteins, genetically encoded fluorescent biosensors have emerged as robust tools for visualizing dynamic signaling events. In contrast, optogenetic protein constructs permit laser-mediated control of signal receptors and effectors within live cells, organoids, and even model organisms. In this paper, we review the basic principles underlying novel biosensors and optogenetic tools and highlight how recent studies in cutaneous biology have leveraged these imaging strategies to illuminate the spatiotemporal signals regulating epidermal development, barrier formation, and tissue homeostasis.
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Affiliation(s)
- Shivam A Zaver
- Division of Dermatology, Department of Medicine, University of Washington, Seattle, Washington, USA; Medical Scientist Training Program, University of Washington, Seattle, Washington, USA
| | - Christopher J Johnson
- Division of Dermatology, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Andre Berndt
- Department of Bioengineering, University of Washington, Seattle, Washington, USA; Institute for Stem Cell and Regenerative Medicine (ISCRM), University of Washington, Seattle, Washington, USA
| | - Cory L Simpson
- Division of Dermatology, Department of Medicine, University of Washington, Seattle, Washington, USA; Institute for Stem Cell and Regenerative Medicine (ISCRM), University of Washington, Seattle, Washington, USA.
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5
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Pelus A, Bordes G, Barbe S, Bouchiba Y, Burnard C, Cortés J, Enjalbert B, Esque J, Estaña A, Fauré R, Henras AK, Heux S, Le Men C, Millard P, Nouaille S, Pérochon J, Toanen M, Truan G, Verdier A, Wagner C, Romeo Y, Montanier CY. A tripartite carbohydrate-binding module to functionalize cellulose nanocrystals. Biomater Sci 2021; 9:7444-7455. [PMID: 34647546 DOI: 10.1039/d1bm01156a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The development of protein and microorganism engineering have led to rising expectations of biotechnology in the design of emerging biomaterials, putatively of high interest to reduce our dependence on fossil carbon resources. In this way, cellulose, a renewable carbon based polysaccharide and derived products, displays unique properties used in many industrial applications. Although the functionalization of cellulose is common, it is however limited in terms of number and type of functions. In this work, a Carbohydrate-Binding Module (CBM) was used as a central core to provide a versatile strategy to bring a large diversity of functions to cellulose surfaces. CBM3a from Clostridium thermocellum, which has a high affinity for crystalline cellulose, was flanked through linkers with a streptavidin domain and an azide group introduced through a non-canonical amino acid. Each of these two extra domains was effectively produced and functionalized with a variety of biological and chemical molecules. Structural properties of the resulting tripartite chimeric protein were investigated using molecular modelling approaches, and its potential for the multi-functionalization of cellulose was confirmed experimentally. As a proof of concept, we show that cellulose can be labelled with a fluorescent version of the tripartite protein grafted to magnetic beads and captured using a magnet.
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Affiliation(s)
- Angeline Pelus
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gaëlle Bordes
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Sophie Barbe
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Younes Bouchiba
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Callum Burnard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Juan Cortés
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Brice Enjalbert
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Jeremy Esque
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Régis Fauré
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Anthony K Henras
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Stéphanie Heux
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Claude Le Men
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Julien Pérochon
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Marion Toanen
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gilles Truan
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Amandine Verdier
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Camille Wagner
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Yves Romeo
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
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6
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Wu T, Pang Y, Ai HW. Circularly Permuted Far-Red Fluorescent Proteins. BIOSENSORS 2021; 11:438. [PMID: 34821654 PMCID: PMC8615523 DOI: 10.3390/bios11110438] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/01/2021] [Accepted: 11/02/2021] [Indexed: 12/22/2022]
Abstract
The color palette of genetically encoded fluorescent protein indicators (GEFPIs) has expanded rapidly in recent years. GEFPIs with excitation and emission within the "optical window" above 600 nm are expected to be superior in many aspects, such as enhanced tissue penetration, reduced autofluorescence and scattering, and lower phototoxicity. Circular permutation of fluorescent proteins (FPs) is often the first step in the process of developing single-FP-based GEFPIs. This study explored the tolerance of two far-red FPs, mMaroon1 and mCarmine, towards circular permutation. Several initial constructs were built according to previously reported circularly permuted topologies for other FP analogs. Mutagenesis was then performed on these constructs and screened for fluorescent variants. As a result, five circularly permuted far-red FPs (cpFrFPs) with excitation and emission maxima longer than 600 nm were identified. Some displayed appreciable brightness and efficient chromophore maturation. These cpFrFPs variants could be intriguing starting points to further engineer far-red GEFPIs for in vivo tissue imaging.
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Affiliation(s)
- Tianchen Wu
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
| | - Yu Pang
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
| | - Hui-wang Ai
- Department of Molecular Physiology and Biological Physics, and Center for Membrane and Cell Physiology, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; (T.W.); (Y.P.)
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
- The UVA Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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7
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Formaglio P, Alabdullah M, Siokis A, Handschuh J, Sauerland I, Fu Y, Krone A, Gintschel P, Stettin J, Heyde S, Mohr J, Philipsen L, Schröder A, Robert PA, Zhao G, Khailaie S, Dudeck A, Bertrand J, Späth GF, Kahlfuß S, Bousso P, Schraven B, Huehn J, Binder S, Meyer-Hermann M, Müller AJ. Nitric oxide controls proliferation of Leishmania major by inhibiting the recruitment of permissive host cells. Immunity 2021; 54:2724-2739.e10. [PMID: 34687607 PMCID: PMC8691385 DOI: 10.1016/j.immuni.2021.09.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 08/04/2021] [Accepted: 09/28/2021] [Indexed: 11/27/2022]
Abstract
Nitric oxide (NO) is an important antimicrobial effector but also prevents unnecessary tissue damage by shutting down the recruitment of monocyte-derived phagocytes. Intracellular pathogens such as Leishmania major can hijack these cells as a niche for replication. Thus, NO might exert containment by restricting the availability of the cellular niche required for efficient pathogen proliferation. However, such indirect modes of action remain to be established. By combining mathematical modeling with intravital 2-photon biosensors of pathogen viability and proliferation, we show that low L. major proliferation results not from direct NO impact on the pathogen but from reduced availability of proliferation-permissive host cells. Although inhibiting NO production increases recruitment of these cells, and thus pathogen proliferation, blocking cell recruitment uncouples the NO effect from pathogen proliferation. Therefore, NO fulfills two distinct functions for L. major containment: permitting direct killing and restricting the supply of proliferation-permissive host cells. Direct killing of L. major by NO occurs only during the peak of the immune response Efficient L. major proliferation requires newly recruited monocyte-derived cells Loss of NO production increases both pathogen proliferation and monocyte recruitment NO dampens L. major proliferation indirectly, limiting the pathogen’s cellular niche
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Affiliation(s)
- Pauline Formaglio
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany.
| | - Mohamad Alabdullah
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Anastasios Siokis
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Juliane Handschuh
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Ina Sauerland
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Yan Fu
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Anna Krone
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Patricia Gintschel
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Juliane Stettin
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Sandrina Heyde
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Juliane Mohr
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Lars Philipsen
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Anja Schröder
- Experimental Orthopedics, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto von Guericke University, Magdeburg 39120, Germany
| | - Philippe A Robert
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany; Department of Immunology, University of Oslo, Oslo 0372, Norway
| | - Gang Zhao
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Sahamoddin Khailaie
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Anne Dudeck
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Jessica Bertrand
- Experimental Orthopedics, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto von Guericke University, Magdeburg 39120, Germany
| | - Gerald F Späth
- Molecular Parasitology and Signalling Unit, Institut Pasteur, Paris 75015, France
| | - Sascha Kahlfuß
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Philippe Bousso
- Dynamics of Immune Responses Unit, Institut Pasteur, INSERM U1223, Paris 75015, France
| | - Burkhart Schraven
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Jochen Huehn
- Department Experimental Immunology, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany; Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover 30625, Germany
| | - Sebastian Binder
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany
| | - Michael Meyer-Hermann
- Department of Systems Immunology and Braunschweig Integrated Centre of Systems Biology, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany; Institute of Biochemistry, Biotechnology and Bioinformatics, Technische Universität Braunschweig, Braunschweig 38106, Germany
| | - Andreas J Müller
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I(3)), Otto-von-Guericke-University, Magdeburg 39120, Germany; Intravital Microscopy of Infection and Immunity, Helmholtz Centre for Infection Research, Braunschweig 38124, Germany.
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8
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Kim H, Seong J. Fluorescent Protein-Based Autophagy Biosensors. MATERIALS 2021; 14:ma14113019. [PMID: 34199451 PMCID: PMC8199620 DOI: 10.3390/ma14113019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 11/16/2022]
Abstract
Autophagy is an essential cellular process of self-degradation for dysfunctional or unnecessary cytosolic constituents and organelles. Dysregulation of autophagy is thus involved in various diseases such as neurodegenerative diseases. To investigate the complex process of autophagy, various biochemical, chemical assays, and imaging methods have been developed. Here we introduce various methods to study autophagy, in particular focusing on the review of designs, principles, and limitations of the fluorescent protein (FP)-based autophagy biosensors. Different physicochemical properties of FPs, such as pH-sensitivity, stability, brightness, spectral profile, and fluorescence resonance energy transfer (FRET), are considered to design autophagy biosensors. These FP-based biosensors allow for sensitive detection and real-time monitoring of autophagy progression in live cells with high spatiotemporal resolution. We also discuss future directions utilizing an optobiochemical strategy to investigate the in-depth mechanisms of autophagy. These cutting-edge technologies will further help us to develop the treatment strategies of autophagy-related diseases.
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Affiliation(s)
- Heejung Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
- Department of Converging Science and Technology, Kyung Hee University, Seoul 02453, Korea
| | - Jihye Seong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
- Department of Converging Science and Technology, Kyung Hee University, Seoul 02453, Korea
- Correspondence:
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9
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Scales JL, Koroma DC, Oancea E. Single organelle measurements of melanosome pH using the novel ratiometric indicator RpHiMEL. Methods Enzymol 2021; 654:315-344. [PMID: 34120720 DOI: 10.1016/bs.mie.2021.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Melanocytes are specialized cells that produce melanin pigments responsible for skin, hair, and eye pigmentation. The synthesis and storage of melanin occurs in unique lysosome-related organelles called melanosomes, which regulate melanin production via complex regulatory mechanisms. Maintenance of the melanosome luminal ionic environment and pH is crucial for proper function of the main melanogenic enzymes. Defects in genes encoding pH-regulating melanosomal proteins result in oculocutaneous albinism, which is characterized by hypopigmentation, impaired vision, and increased susceptibility to skin and eye cancers. We recently uncovered several ion channels and transporters that modulate melanin synthesis by acidifying or neutralizing the luminal pH of melanosomes. However, our understanding of how melanosomes and other related organelles maintain their luminal pH is far from complete. The study of melanosome pH regulation requires robust imaging and quantification tools. Despite recent advances in the development of such methods, many limitations remain, particularly for quantitative analysis of individual organelle pH. In this chapter, we will provide an overview of the available methods used for melanosome pH determination, including their advantages, limitations, and challenges. To address the critical, unmet need for reliable melanosome pH quantification tools, we engineered a novel genetically encoded, ratiometric pH sensor for melanosomes that we named RpHiMEL. Here, we describe the design and optimization of RpHiMEL, and provide a pH quantification method for individual melanosomes in live cells. We demonstrate that RpHiMEL is a highly versatile tool with the potential to advance our understanding of pH regulation in melanosomes and related organelles.
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Affiliation(s)
- Jessica L Scales
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, United States
| | - Donald C Koroma
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, United States
| | - Elena Oancea
- Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI, United States.
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10
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Liu A, Huang X, He W, Xue F, Yang Y, Liu J, Chen L, Yuan L, Xu P. pHmScarlet is a pH-sensitive red fluorescent protein to monitor exocytosis docking and fusion steps. Nat Commun 2021; 12:1413. [PMID: 33658493 PMCID: PMC7930027 DOI: 10.1038/s41467-021-21666-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/05/2021] [Indexed: 12/21/2022] Open
Abstract
pH-sensitive fluorescent proteins (FPs) are highly advantageous for the non-invasive monitoring of exocytosis events. Superecliptic pHluorin (SEP), a green pH-sensitive FP, has been widely used for imaging single-vesicle exocytosis. However, the docking step cannot be visualized using this FP, since the fluorescence signal inside vesicles is too low to be observed during docking process. Among the available red pH-sensitive FPs, none is comparable to SEP for practical applications due to unoptimized pH-sensitivity and fluorescence brightness or severe photochromic behavior. In this study, we engineer a bright and photostable red pH-sensitive FP, named pHmScarlet, which compared to other red FPs has higher pH sensitivity and enables the simultaneous detection of vesicle docking and fusion. pHmScarlet can also be combined with SEP for dual-color imaging of two individual secretory events. Furthermore, although the emission wavelength of pHmScarlet is red-shifted compared to that of SEP, its spatial resolution is high enough to show the ring structure of vesicle fusion pores using Hessian structured illumination microscopy (Hessian-SIM).
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Affiliation(s)
- Anyuan Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Xiaoshuai Huang
- Biomedical Engineering Department, Peking University, Beijing, China
| | - Wenting He
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Fudong Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yanrui Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
| | - Jiajia Liu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Science, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lin Yuan
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
| | - Pingyong Xu
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
- Department of Clinical Laboratory, Children's Hospital of Chongqing Medical University, Chongqing, China.
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11
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Glutamine Uptake via SNAT6 and Caveolin Regulates Glutamine-Glutamate Cycle. Int J Mol Sci 2021; 22:ijms22031167. [PMID: 33503881 PMCID: PMC7865731 DOI: 10.3390/ijms22031167] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 01/13/2021] [Accepted: 01/19/2021] [Indexed: 12/22/2022] Open
Abstract
SLC38A6 (SNAT6) is the only known member of the SLC38 family that is expressed exclusively in the excitatory neurons of the brain. It has been described as an orphan transporter with an unknown substrate profile, therefore very little is known about SNAT6. In this study, we addressed the substrate specificity, mechanisms for internalization of SNAT6, and the regulatory role of SNAT6 with specific insights into the glutamate-glutamine cycle. We used tritium-labeled amino acids in order to demonstrate that SNAT6 is functioning as a glutamine and glutamate transporter. SNAT6 revealed seven predicted transmembrane segments in a homology model and was localized to caveolin rich sites at the plasma membrane. SNAT6 has high degree of specificity for glutamine and glutamate. Presence of these substrates enables formation of SNAT6-caveolin complexes that aids in sodium dependent trafficking of SNAT6 off the plasma membrane. To further understand its mode of action, several potential interacting partners of SNAT6 were identified using bioinformatics. Among them where CTP synthase 2 (CTPs2), phosphate activated glutaminase (Pag), and glutamate metabotropic receptor 2 (Grm2). Co-expression analysis, immunolabeling with co-localization analysis and proximity ligation assays of these three proteins with SNAT6 were performed to investigate possible interactions. SNAT6 can cycle between cytoplasm and plasma membrane depending on availability of substrates and interact with Pag, synaptophysin, CTPs2, and Grm2. Our data suggest a potential role of SNAT6 in glutamine uptake at the pre-synaptic terminal of excitatory neurons. We propose here a mechanistic model of SNAT6 trafficking that once internalized influences the glutamate-glutamine cycle in presence of its potential interacting partners.
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12
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Dos Santos NV, Saponi CF, Ryan TM, Primo FL, Greaves TL, Pereira JFB. Reversible and irreversible fluorescence activity of the Enhanced Green Fluorescent Protein in pH: Insights for the development of pH-biosensors. Int J Biol Macromol 2020; 164:3474-3484. [PMID: 32882278 DOI: 10.1016/j.ijbiomac.2020.08.224] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/09/2020] [Accepted: 08/28/2020] [Indexed: 11/17/2022]
Abstract
Enhanced Green Fluorescent Protein (EGFP) is a biomolecule with intense and natural fluorescence, with biological and medical applications. Although widely used as a biomarker in research, its application as a biosensor is limited by the lack of in-depth knowledge regarding its structure and behavior in adverse conditions. This study is focused on addressing this need by evaluating EGFP activity and structure at different pH using three-dimensional fluorescence, circular dichroism and small-angle X-ray scattering. The focus was on the reversibility of the process to gain insights for the development of biocompatible pH-biosensors. EGFP was highly stable at alkaline pH and quenched from neutral-to-acidic pH. Above pH 6.0, the fluorescence loss was almost completely reversible on return to neutral pH, but only partially reversible from pH 5.0 to 2.0. This work updates the knowledge regarding EGFP behavior in pH by accounting for the recent data on its structure. Hence, it is evident that EGFP presents the required properties for use as natural, biocompatible and environmentally friendly neutral to acidic pH-biosensors.
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Affiliation(s)
- Nathalia Vieira Dos Santos
- Department of Engineering of Bioprocesses and Biotechnology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jaú/Km 01, 14800-903 Araraquara, SP, Brazil; School of Science, College of Science, Engineering and Health, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia
| | - Carolina Falaschi Saponi
- Department of Engineering of Bioprocesses and Biotechnology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jaú/Km 01, 14800-903 Araraquara, SP, Brazil; School of Science, College of Science, Engineering and Health, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia
| | - Timothy M Ryan
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168, Australia
| | - Fernando L Primo
- Department of Engineering of Bioprocesses and Biotechnology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jaú/Km 01, 14800-903 Araraquara, SP, Brazil
| | - Tamar L Greaves
- School of Science, College of Science, Engineering and Health, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia
| | - Jorge F B Pereira
- Department of Engineering of Bioprocesses and Biotechnology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jaú/Km 01, 14800-903 Araraquara, SP, Brazil; Univ Coimbra, CIEPQPF, Department of Chemical Engineering, Rua Sílvio Lima, Pólo II - Pinhal de Marrocos, 3030-790 Coimbra, Portugal.
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13
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Morimoto YV, Namba K, Minamino T. GFP Fusion to the N-Terminus of MotB Affects the Proton Channel Activity of the Bacterial Flagellar Motor in Salmonella. Biomolecules 2020; 10:E1255. [PMID: 32872412 PMCID: PMC7564593 DOI: 10.3390/biom10091255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 12/28/2022] Open
Abstract
The bacterial flagellar motor converts the energy of proton flow through the MotA/MotB complex into mechanical works required for motor rotation. The rotational force is generated by electrostatic interactions between the stator protein MotA and the rotor protein FliG. The Arg-90 and Glu-98 from MotA interact with Asp-289 and Arg-281 of FliG, respectively. An increase in the expression level of the wild-type MotA/MotB complex inhibits motility of the gfp-motBfliG(R281V) mutant but not the fliG(R281V) mutant, suggesting that the MotA/GFP-MotB complex cannot work together with wild-type MotA/MotB in the presence of the fliG(R281V) mutation. However, it remains unknown why. Here, we investigated the effect of the GFP fusion to MotB at its N-terminus on the MotA/MotB function. Over-expression of wild-type MotA/MotB significantly reduced the growth rate of the gfp-motBfliG(R281V) mutant. The over-expression of the MotA/GFP-MotB complex caused an excessive proton leakage through its proton channel, thereby inhibiting cell growth. These results suggest that the GFP tag on the MotB N-terminus affects well-regulated proton translocation through the MotA/MotB proton channel. Therefore, we propose that the N-terminal cytoplasmic tail of MotB couples the gating of the proton channel with the MotA-FliG interaction responsible for torque generation.
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Affiliation(s)
- Yusuke V. Morimoto
- Department of Physics and Information Technology, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502, Japan
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; (K.N.); (T.M.)
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; (K.N.); (T.M.)
- RIKEN Spring-8 Center & Center for Biosystems Dynamics Research (BDR), 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan; (K.N.); (T.M.)
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14
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Kostyuk AI, Kokova AD, Podgorny OV, Kelmanson IV, Fetisova ES, Belousov VV, Bilan DS. Genetically Encoded Tools for Research of Cell Signaling and Metabolism under Brain Hypoxia. Antioxidants (Basel) 2020; 9:E516. [PMID: 32545356 PMCID: PMC7346190 DOI: 10.3390/antiox9060516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/04/2020] [Accepted: 06/06/2020] [Indexed: 02/08/2023] Open
Abstract
Hypoxia is characterized by low oxygen content in the tissues. The central nervous system (CNS) is highly vulnerable to a lack of oxygen. Prolonged hypoxia leads to the death of brain cells, which underlies the development of many pathological conditions. Despite the relevance of the topic, different approaches used to study the molecular mechanisms of hypoxia have many limitations. One promising lead is the use of various genetically encoded tools that allow for the observation of intracellular parameters in living systems. In the first part of this review, we provide the classification of oxygen/hypoxia reporters as well as describe other genetically encoded reporters for various metabolic and redox parameters that could be implemented in hypoxia studies. In the second part, we discuss the advantages and disadvantages of the primary hypoxia model systems and highlight inspiring examples of research in which these experimental settings were combined with genetically encoded reporters.
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Affiliation(s)
- Alexander I. Kostyuk
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Aleksandra D. Kokova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Oleg V. Podgorny
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Koltzov Institute of Developmental Biology, 119334 Moscow, Russia
| | - Ilya V. Kelmanson
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Elena S. Fetisova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Vsevolod V. Belousov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
- Institute for Cardiovascular Physiology, Georg August University Göttingen, D-37073 Göttingen, Germany
- Federal Center for Cerebrovascular Pathology and Stroke, 117997 Moscow, Russia
| | - Dmitry S. Bilan
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia; (A.I.K.); (A.D.K.); (O.V.P.); (I.V.K.); (E.S.F.); (V.V.B.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
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15
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Quiroz FG, Fiore VF, Levorse J, Polak L, Wong E, Pasolli HA, Fuchs E. Liquid-liquid phase separation drives skin barrier formation. Science 2020; 367:367/6483/eaax9554. [PMID: 32165560 DOI: 10.1126/science.aax9554] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 11/20/2019] [Accepted: 01/22/2020] [Indexed: 12/20/2022]
Abstract
At the body surface, skin's stratified squamous epithelium is challenged by environmental extremes. The surface of the skin is composed of enucleated, flattened surface squames. They derive from underlying, transcriptionally active keratinocytes that display filaggrin-containing keratohyalin granules (KGs) whose function is unclear. Here, we found that filaggrin assembles KGs through liquid-liquid phase separation. The dynamics of phase separation governed terminal differentiation and were disrupted by human skin barrier disease-associated mutations. We used fluorescent sensors to investigate endogenous phase behavior in mice. Phase transitions during epidermal stratification crowded cellular spaces with liquid-like KGs whose coalescence was restricted by keratin filament bundles. We imaged cells as they neared the skin surface and found that environmentally regulated KG phase dynamics drive squame formation. Thus, epidermal structure and function are driven by phase-separation dynamics.
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Affiliation(s)
- Felipe Garcia Quiroz
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA
| | - Vincent F Fiore
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA
| | - John Levorse
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA
| | - Lisa Polak
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA
| | - Ellen Wong
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA
| | - H Amalia Pasolli
- Electron Microscopy Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Elaine Fuchs
- Howard Hughes Medical Institute, Robin Chemers Neustein Laboratory of Mammalian Cell Biology and Development, The Rockefeller University, New York, NY 10065, USA.
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16
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Handschuh J, Amore J, Müller AJ. From the Cradle to the Grave of an Infection: Host-Pathogen Interaction Visualized by Intravital Microscopy. Cytometry A 2019; 97:458-470. [PMID: 31777152 DOI: 10.1002/cyto.a.23938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/12/2019] [Accepted: 11/06/2019] [Indexed: 12/11/2022]
Abstract
During infections, interactions between host immune cells and the pathogen occur in distinct anatomical locations and along defined time scales. This can best be assessed in the physiological context of an infection in the living tissue. Consequently, intravital imaging has enabled us to dissect the critical phases and events throughout an infection in real time in living tissues. Specifically, advances in visualizing specific cell types and individual pathogens permitted tracking the early events of tissue invasion of the pathogen, cellular interactions involved in the induction of the immune response as well the events implicated in clearance of the infection. In this respect, two vantage points have evolved since the initial employment of this technique in the field of infection biology. On the one hand, strategies acquired by the pathogen to establish within the host and circumvent or evade the immune defenses have been elucidated. On the other hand, analyzing infections from the immune system's perspective has led to insights into the dynamic cellular interactions that are involved in the initial recognition of the pathogen, immune induction as well as effector function delivery and immunopathology. Furthermore, an increasing interest in probing functional parameters in vivo has emerged, such as the analysis of pathogen reactivity to stress conditions imposed by the host organism in order to mediate clearance upon pathogen encounter. Here, we give an overview on recent intravital microscopy findings of host-pathogen interactions along the course of an infection, from both the immune system's and pathogen's perspectives. We also discuss recent developments and future perspectives in extracting intravital information beyond the localization of pathogens and their interaction with immune cells. Such reporter systems on the pathogen's physiological state and immune cell functions may prove useful in dissecting the functional dynamics of host-pathogen interactions. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.
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Affiliation(s)
- Juliane Handschuh
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I3), Otto-von-Guericke-University, 39120, Magdeburg, Germany
| | - Jonas Amore
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I3), Otto-von-Guericke-University, 39120, Magdeburg, Germany
| | - Andreas J Müller
- Institute of Molecular and Clinical Immunology, Health Campus Immunology Infectiology and Inflammation (GC-I3), Otto-von-Guericke-University, 39120, Magdeburg, Germany.,Intravital Microscopy of Infection and Immunity, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
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17
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Haynes EP, Rajendran M, Henning CK, Mishra A, Lyon AM, Tantama M. Quantifying Acute Fuel and Respiration Dependent pH Homeostasis in Live Cells Using the mCherryTYG Mutant as a Fluorescence Lifetime Sensor. Anal Chem 2019; 91:8466-8475. [PMID: 31247720 DOI: 10.1021/acs.analchem.9b01562] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Intracellular pH plays a key role in physiology, and its measurement in living specimens remains a crucial task in biology. Fluorescent protein-based pH sensors have gained widespread use, but there is limited spectral diversity for multicolor detection, and it remains a challenge to measure absolute pH values. Here we demonstrate that mCherryTYG is an excellent fluorescence lifetime pH sensor that significantly expands the modalities available for pH quantification in live cells. We first report the 1.09 Å X-ray crystal structure of mCherryTYG, exhibiting a fully matured chromophore. We next determine that it has an extraordinarily large dynamic range with a 2 ns lifetime change from pH 5.5 to 9.0. Critically, we find that the sensor maintains a p Ka of 6.8 independent of environment, whether as the purified protein in solution or expressed in live cells. Furthermore, the lifetime measurements are robustly independent of total fluorescence intensity and scatter. We demonstrate that mCherryTYG is a highly effective sensor using time-resolved fluorescence spectroscopy on live-cell suspensions, which has been previously overlooked as an easily accessible approach for quantifying intracellular pH. As a red fluorescent sensor, we also demonstrate that mCherryTYG is spectrally compatible with the ATeam sensor and EGFP for simultaneous dual-color measurements of intracellular pH, ATP, and extracellular pH. In a proof-of-concept, we quantify acute respiration-dependent pH homeostasis that exhibits a stoichiometric relationship with the ATP-generating capacity of the carbon fuel choice in E. coli. Broadly speaking, our work presents a previously unemployed methodology that will greatly facilitate continuous pH quantification.
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18
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 293] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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19
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Genetically encoded fluorescent indicators for live cell pH imaging. Biochim Biophys Acta Gen Subj 2018; 1862:2924-2939. [PMID: 30279147 DOI: 10.1016/j.bbagen.2018.09.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/17/2018] [Accepted: 09/17/2018] [Indexed: 02/04/2023]
Abstract
BACKGROUND Intracellular pH underlies most cellular processes. There is emerging evidence of a pH-signaling role in plant cells and microorganisms. Dysregulation of pH is associated with human diseases, such as cancer and Alzheimer's disease. SCOPE OF REVIEW In this review, we attempt to provide a summary of the progress that has been made in the field during the past two decades. First, we present an overview of the current state of the design and applications of fluorescent protein (FP)-based pH indicators. Then, we turn our attention to the development and applications of hybrid pH sensors that combine the capabilities of non-GFP fluorophores with the advantages of genetically encoded tags. Finally, we discuss recent advances in multicolor pH imaging and the applications of genetically encoded pH sensors in multiparameter imaging. MAJOR CONCLUSIONS Genetically encoded pH sensors have proven to be indispensable noninvasive tools for selective targeting to different cellular locations. Although a variety of genetically encoded pH sensors have been designed and applied at the single cell level, there is still much room for improvements and future developments of novel powerful tools for pH imaging. Among the most pressing challenges in this area is the design of brighter redshifted sensors for tissue research and whole animal experiments. GENERAL SIGNIFICANCE The design of precise pH measuring instruments is one of the important goals in cell biochemistry and may give rise to the development of new powerful diagnostic tools for various diseases.
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20
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Rajendran M, Claywell B, Haynes EP, Scales U, Henning CK, Tantama M. Imaging pH Dynamics Simultaneously in Two Cellular Compartments Using a Ratiometric pH-Sensitive Mutant of mCherry. ACS OMEGA 2018; 3:9476-9486. [PMID: 30197999 PMCID: PMC6120727 DOI: 10.1021/acsomega.8b00655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 08/06/2018] [Indexed: 05/09/2023]
Abstract
The regulation of pH is essential for proper organelle function, and organelle-specific changes in pH often reflect the dynamics of physiological signaling and metabolism. For example, mitochondrial energy production depends on the proton gradient maintained between the alkaline mitochondrial matrix and neutral cytosol. However, we still lack a quantitative understanding of how pH dynamics are coupled between compartments and how pH gradients are regulated at organelle boundaries. Genetically encoded pH sensors are well suited to address this problem because they can be targeted to specific subcellular locations and they facilitate live, single-cell analysis. However, most of these pH sensors are derivatives of green and yellow fluorescent proteins that are not spectrally compatible for dual-compartment imaging. Therefore, there is a need for ratiometric red fluorescent protein pH sensors that enable quantitative multicolor imaging of spatially resolved pH dynamics. In this work, we demonstrate that the I158E/Q160A mutant of the red fluorescent protein mCherry is an effective ratiometric pH sensor. It has a pKa of 7.3 and a greater than 3-fold change in ratio signal. To demonstrate its utility in cells, we measured activity and metabolism-dependent pH dynamics in cultured primary neurons and neuroblastoma cells. Furthermore, we were able to image pH changes simultaneously in the cytosol and mitochondria by using the mCherryEA mutant together with the green fluorescent pH sensor, ratiometric-pHluorin. Our results demonstrate the feasibility of studying interorganelle pH dynamics in live cells over time and the broad applicability of these sensors in studying the role of pH regulation in metabolism and signaling.
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Affiliation(s)
- Megha Rajendran
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
| | - Benjamin Claywell
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
| | - Emily P. Haynes
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
| | - Umi Scales
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
| | - Chace K. Henning
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
| | - Mathew Tantama
- Department
of Chemistry, Institute for Integrative Neuroscience, and Institute of Inflammation, Immunology,
and Infectious Disease, Purdue University, 560 Oval Drive,
P.O. Box 68, West Lafayette, Indiana 47907, United States
- E-mail: . Phone: 765-494-5312
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21
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Lin B, Fan L, Ge J, Zhang W, Zhang C, Dong C, Shuang S. A naphthalene-based fluorescent probe with a large Stokes shift for mitochondrial pH imaging. Analyst 2018; 143:5054-5060. [DOI: 10.1039/c8an01371c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A naphthalene-based fluorescent pH probe with a pKa of 8.8 for imaging mitochondrial pH changes in live cells.
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Affiliation(s)
- Bo Lin
- College of Chemistry and Chemical Engineering
- Shanxi University
- Taiyuan 030006
- China
| | - Li Fan
- Institute of Environmental Science
- Shanxi University
- Taiyuan 030006
- China
| | - Jinyin Ge
- College of Chemistry and Chemical Engineering
- Shanxi University
- Taiyuan 030006
- China
| | - Wenjia Zhang
- College of Chemistry and Chemical Engineering
- Shanxi University
- Taiyuan 030006
- China
| | - Caihong Zhang
- College of Chemistry and Chemical Engineering
- Shanxi University
- Taiyuan 030006
- China
| | - Chuan Dong
- Institute of Environmental Science
- Shanxi University
- Taiyuan 030006
- China
| | - Shaomin Shuang
- College of Chemistry and Chemical Engineering
- Shanxi University
- Taiyuan 030006
- China
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22
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Rossano AJ, Romero MF. Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator. J Vis Exp 2017. [PMID: 28829430 DOI: 10.3791/55698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Epithelial ion transport is vital to systemic ion homeostasis as well as maintenance of essential cellular electrochemical gradients. Intracellular pH (pHi) is influenced by many ion transporters and thus monitoring pHi is a useful tool for assessing transporter activity. Modern Genetically Encoded pH-Indicators (GEpHIs) provide optical quantification of pHi in intact cells on a cellular and subcellular scale. This protocol describes real-time quantification of cellular pHi regulation in Malpighian Tubules (MTs) of Drosophila melanogaster through ex vivo live-imaging of pHerry, a pseudo-ratiometric GEpHI with a pKa well-suited to track pH changes in the cytosol. Extracted adult fly MTs are composed of morphologically and functionally distinct sections of single-cell layer epithelia, and can serve as an accessible and genetically tractable model for investigation of epithelial transport. GEpHIs offer several advantages over conventional pH-sensitive fluorescent dyes and ion-selective electrodes. GEpHIs can label distinct cell populations provided appropriate promoter elements are available. This labeling is particularly useful in ex vivo, in vivo, and in situ preparations, which are inherently heterogeneous. GEpHIs also permit quantification of pHi in intact tissues over time without need for repeated dye treatment or tissue externalization. The primary drawback of current GEpHIs is the tendency to aggregate in cytosolic inclusions in response to tissue damage and construct over-expression. These shortcomings, their solutions, and the inherent advantages of GEpHIs are demonstrated in this protocol through assessment of basolateral proton (H+) transport in functionally distinct principal and stellate cells of extracted fly MTs. The techniques and analysis described are readily adaptable to a wide variety of vertebrate and invertebrate preparations, and the sophistication of the assay can be scaled from teaching labs to intricate determination of ion flux via specific transporters.
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Affiliation(s)
- Adam J Rossano
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine;
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine; Department of Nephrology and Hypertension, Mayo Clinic College of Medicine;
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23
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Bolbat A, Schultz C. Recent developments of genetically encoded optical sensors for cell biology. Biol Cell 2016; 109:1-23. [PMID: 27628952 DOI: 10.1111/boc.201600040] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/06/2016] [Accepted: 09/09/2016] [Indexed: 12/14/2022]
Abstract
Optical sensors are powerful tools for live cell research as they permit to follow the location, concentration changes or activities of key cellular players such as lipids, ions and enzymes. Most of the current sensor probes are based on fluorescence which provides great spatial and temporal precision provided that high-end microscopy is used and that the timescale of the event of interest fits the response time of the sensor. Many of the sensors developed in the past 20 years are genetically encoded. There is a diversity of designs leading to simple or sometimes complicated applications for the use in live cells. Genetically encoded sensors began to emerge after the discovery of fluorescent proteins, engineering of their improved optical properties and the manipulation of their structure through application of circular permutation. In this review, we will describe a variety of genetically encoded biosensor concepts, including those for intensiometric and ratiometric sensors based on single fluorescent proteins, Forster resonance energy transfer-based sensors, sensors utilising bioluminescence, sensors using self-labelling SNAP- and CLIP-tags, and finally tetracysteine-based sensors. We focus on the newer developments and discuss the current approaches and techniques for design and application. This will demonstrate the power of using optical sensors in cell biology and will help opening the field to more systematic applications in the future.
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Affiliation(s)
- Andrey Bolbat
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL), Cell Biology & Biophysics Unit, Heidelberg, 69117, Germany
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24
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Silverman JM, Imperiali B. Bacterial N-Glycosylation Efficiency Is Dependent on the Structural Context of Target Sequons. J Biol Chem 2016; 291:22001-22010. [PMID: 27573243 DOI: 10.1074/jbc.m116.747121] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Indexed: 01/08/2023] Open
Abstract
Site selectivity of protein N-linked glycosylation is dependent on many factors, including accessibility of the modification site, amino acid composition of the glycosylation consensus sequence, and cellular localization of target proteins. Previous studies have shown that the bacterial oligosaccharyltransferase, PglB, of Campylobacter jejuni favors acceptor proteins with consensus sequences ((D/E)X1NX2(S/T), where X1,2 ≠ proline) in flexible, solvent-exposed motifs; however, several native glycoproteins are known to harbor consensus sequences within structured regions of the acceptor protein, suggesting that unfolding or partial unfolding is required for efficient N-linked glycosylation in the native environment. To derive insight into these observations, we generated structural homology models of the N-linked glycoproteome of C. jejuni This evaluation highlights the potential diversity of secondary structural conformations of previously identified N-linked glycosylation sequons. Detailed assessment of PglB activity with a structurally characterized acceptor protein, PEB3, demonstrated that this natively folded substrate protein is not efficiently glycosylated in vitro, whereas structural destabilization increases glycosylation efficiency. Furthermore, in vivo glycosylation studies in both glyco-competent Escherichia coli and the native system, C. jejuni, revealed that efficient glycosylation of glycoproteins, AcrA and PEB3, depends on translocation to the periplasmic space via the general secretory pathway. Our studies provide quantitative evidence that many acceptor proteins are likely to be N-linked-glycosylated before complete folding and suggest that PglB activity is coupled to general secretion-mediated translocation to the periplasm. This work extends our understanding of the molecular mechanisms underlying N-linked glycosylation in bacteria.
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Affiliation(s)
- Julie Michelle Silverman
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Barbara Imperiali
- From the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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25
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Wilson JD, Shelby SA, Holowka D, Baird B. Rab11 Regulates the Mast Cell Exocytic Response. Traffic 2016; 17:1027-41. [PMID: 27288050 DOI: 10.1111/tra.12418] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 06/07/2016] [Accepted: 06/07/2016] [Indexed: 01/30/2023]
Abstract
Stimulated exocytic events provide a means for physiological communication and are a hallmark of the mast cell-mediated allergic response. In mast cells these processes are triggered by antigen crosslinking of IgE bound to its high-affinity receptor, FcϵRI, on the cell surface. Here we use the endosomal v-SNARE VAMP8, and the lysosomal hydrolase β-hexosaminidase (β-Hex), each C-terminally fused to super-ecliptic pHluorin, to monitor stimulated exocytosis. Using these pHluorin-tagged constructs, we monitor stimulated exocytosis by fluorimetry and visualize individual exocytic events with total internal reflection (TIRF) microscopy. Similar to constitutive recycling endosome (RE) trafficking, we find that stimulated RE exocytosis, monitored by VAMP8, is attenuated by expression of dominant negative (S25N) Rab11. Stimulated β-Hex exocytosis is also reduced in the presence of S25N Rab11, suggesting that expression of this mutant broadly impacts exocytosis. Interestingly, pretreatment with inhibitors of actin polymerization, cytochalasin D or latrunculin A, substantially restores both RE and lysosome exocytosis in cells expressing S25N Rab11. Conversely, stabilizing F-actin with jasplakinolide inhibits antigen-stimulated exocytosis but is not additive with S25N Rab11-mediated inhibition, suggesting that these reagents inhibit related processes. Together, our results suggest that Rab11 participates in the regulation necessary for depolymerization of the actin cytoskeleton during stimulated exocytosis in mast cells.
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Affiliation(s)
- Joshua D Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - Sarah A Shelby
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - David Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
| | - Barbara Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853-1301, USA
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26
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Abstract
Melanin is responsible for pigmentation of skin and hair and is synthesized in a specialized organelle, the melanosome, in melanocytes. A genome-wide association study revealed that the two pore segment channel 2 (TPCN2) gene is strongly linked to pigmentation variations. TPCN2 encodes the two-pore channel 2 (TPC2) protein, a cation channel. Nevertheless, how TPC2 regulates pigmentation remains unknown. Here, we show that TPC2 is expressed in melanocytes and localizes to the melanosome-limiting membrane and, to a lesser extent, to endolysosomal compartments by confocal fluorescence and immunogold electron microscopy. Immunomagnetic isolation of TPC2-containing organelles confirmed its coresidence with melanosomal markers. TPCN2 knockout by means of clustered regularly interspaced short palindromic repeat/CRISPR-associated 9 gene editing elicited a dramatic increase in pigment content in MNT-1 melanocytic cells. This effect was rescued by transient expression of TPC2-GFP. Consistently, siRNA-mediated knockdown of TPC2 also caused a substantial increase in melanin content in both MNT-1 cells and primary human melanocytes. Using a newly developed genetically encoded pH sensor targeted to melanosomes, we determined that the melanosome lumen in TPC2-KO MNT-1 cells and primary melanocytes subjected to TPC2 knockdown is less acidic than in control cells. Fluorescence and electron microscopy analysis revealed that TPC2-KO MNT-1 cells have significantly larger melanosomes than control cells, but the number of organelles is unchanged. TPC2 likely regulates melanosomes pH and size by mediating Ca(2+) release from the organelle, which is decreased in TPC2-KO MNT-1 cells, as determined with the Ca(2+) sensor tyrosinase-GCaMP6. Thus, our data show that TPC2 regulates pigmentation through two fundamental determinants of melanosome function: pH and size.
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27
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Design and development of genetically encoded fluorescent sensors to monitor intracellular chemical and physical parameters. Biophys Rev 2016; 8:121-138. [PMID: 28510054 PMCID: PMC4884202 DOI: 10.1007/s12551-016-0195-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 03/09/2016] [Indexed: 01/26/2023] Open
Abstract
Over the past decades many researchers have made major contributions towards the development of genetically encoded (GE) fluorescent sensors derived from fluorescent proteins. GE sensors are now used to study biological phenomena by facilitating the measurement of biochemical behaviors at various scales, ranging from single molecules to single cells or even whole animals. Here, we review the historical development of GE fluorescent sensors and report on their current status. We specifically focus on the development strategies of the GE sensors used for measuring pH, ion concentrations (e.g., chloride and calcium), redox indicators, membrane potential, temperature, pressure, and molecular crowding. We demonstrate that these fluroescent protein-based sensors have a shared history of concepts and development strategies, and we highlight the most original concepts used to date. We believe that the understanding and application of these various concepts will pave the road for the development of future GE sensors and lead to new breakthroughs in bioimaging.
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28
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Abstract
The field of fluorescent proteins (FPs) is constantly developing. The use of FPs changed the field of life sciences completely, starting a new era of direct observation and quantification of cellular processes. The broad spectrum of FPs (see Fig. 1) with a wide range of characteristics allows their use in many different experiments. This review discusses the use of FPs for imaging in budding yeast (Saccharomyces cerevisiae) and fission yeast Schizosaccharomyces pombe). The information included in this review is relevant for both species unless stated otherwise.
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Affiliation(s)
- Maja Bialecka-Fornal
- Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, CA, 92697, USA
- Center for Complex Biological Systems, University of California, Irvine, CA, 92697, USA
| | - Tatyana Makushok
- Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th Street, San Francisco, CA, 94158, USA
| | - Susanne M Rafelski
- Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, CA, 92697, USA.
- Center for Complex Biological Systems, University of California, Irvine, CA, 92697, USA.
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29
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Loganathan SK, Lukowski CM, Casey JR. The cytoplasmic domain is essential for transport function of the integral membrane transport protein SLC4A11. Am J Physiol Cell Physiol 2015; 310:C161-74. [PMID: 26582474 DOI: 10.1152/ajpcell.00246.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/11/2015] [Indexed: 12/21/2022]
Abstract
Large cytoplasmic domains (CD) are a common feature among integral membrane proteins. In virtually all cases, these CD have a function (e.g., binding cytoskeleton or regulatory factors) separate from that of the membrane domain (MD). Strong associations between CD and MD are rare. Here we studied SLC4A11, a membrane transport protein of corneal endothelial cells, the mutations of which cause genetic corneal blindness. SLC4A11 has a 41-kDa CD and a 57-kDa integral MD. One disease-causing mutation in the CD, R125H, manifests a catalytic defect, suggesting a role of the CD in transport function. Expressed in HEK-293 cells without the CD, MD-SLC4A11 is retained in the endoplasmic reticulum, indicating a folding defect. Replacement of CD-SLC4A11 with green fluorescent protein did not rescue MD-SLC4A11, suggesting some specific role of CD-SLC4A11. Homology modeling revealed that the structure of CD-SLC4A11 is similar to that of the Cl(-)/HCO3(-) exchange protein AE1 (SLC4A1) CD. Fusion to CD-AE1 partially rescued MD-SLC4A11 to the cell surface, suggesting that the structure of CD-AE1 is similar to that of CD-SLC4A11. The CD-AE1-MD-SLC4a11 chimera, however, had no functional activity. We conclude that CD-SLC4A11 has an indispensable role in the transport function of SLC4A11. CD-SLC4A11 forms insoluble precipitates when expressed in bacteria, suggesting that the domain cannot fold properly when expressed alone. Consistent with a strong association between CD-SLC4A11 and MD-SLC4A11, these domains specifically associate when coexpressed in HEK-293 cells. We conclude that SLC4A11 is a rare integral membrane protein in which the CD has strong associations with the integral MD, which contributes to membrane transport function.
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Affiliation(s)
- Sampath K Loganathan
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Chris M Lukowski
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Joseph R Casey
- Membrane Protein Disease Research Group, Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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30
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Ambrosio AL, Boyle JA, Di Pietro SM. TPC2 mediates new mechanisms of platelet dense granule membrane dynamics through regulation of Ca2+ release. Mol Biol Cell 2015. [PMID: 26202466 PMCID: PMC4569316 DOI: 10.1091/mbc.e15-01-0058] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
TPC2 is a component of the platelet dense granule membrane and regulates the formation of perigranular Ca2+ nanodomains that correlate with “kiss-and-run” events and tubule connections. These membrane contacts allow material transfer between organelles and are likely involved in granule maturation. Platelet dense granules (PDGs) are acidic calcium stores essential for normal hemostasis. They develop from late endosomal compartments upon receiving PDG-specific proteins through vesicular trafficking, but their maturation process is not well understood. Here we show that two-pore channel 2 (TPC2) is a component of the PDG membrane that regulates PDG luminal pH and the pool of releasable Ca2+. Using a genetically encoded Ca2+ biosensor and a pore mutant TPC2, we establish the function of TPC2 in Ca2+ release from PDGs and the formation of perigranular Ca2+ nanodomains. For the first time, Ca2+ spikes around PDGs—or any organelle of the endolysosome family—are visualized in real time and revealed to precisely mark organelle “kiss-and-run” events. Further, the presence of membranous tubules transiently connecting PDGs is revealed and shown to be dramatically enhanced by TPC2 in a mechanism that requires ion flux through TPC2. “Kiss-and-run” events and tubule connections mediate transfer of membrane proteins and luminal content between PDGs. The results show that PDGs use previously unknown mechanisms of membrane dynamics and content exchange that are regulated by TPC2.
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Affiliation(s)
- Andrea L Ambrosio
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
| | - Judith A Boyle
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
| | - Santiago M Di Pietro
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870
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31
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Shen Y, Lai T, Campbell RE. Red fluorescent proteins (RFPs) and RFP-based biosensors for neuronal imaging applications. NEUROPHOTONICS 2015; 2:031203. [PMID: 26158012 PMCID: PMC4478792 DOI: 10.1117/1.nph.2.3.031203] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 05/19/2015] [Indexed: 05/23/2023]
Abstract
The inherent advantages of red-shifted fluorescent proteins and fluorescent protein-based biosensors for the study of signaling processes in neurons and other tissues have motivated the development of a plethora of new tools. Relative to green fluorescent proteins (GFPs) and other blue-shifted alternatives, red fluorescent proteins (RFPs) provide the inherent advantages of lower phototoxicity, lower autofluorescence, and deeper tissue penetration associated with longer wavelength excitation light. All other factors being the same, the multiple benefits of using RFPs make these tools seemingly ideal candidates for use in neurons and, ultimately, the brain. However, for many applications, the practical utility of RFPs still falls short of the preferred GFPs. We present an overview of RFPs and RFP-based biosensors, with an emphasis on their reported applications in neuroscience.
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Affiliation(s)
- Yi Shen
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
| | - Tiffany Lai
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
| | - Robert E. Campbell
- University of Alberta, Department of Chemistry, Edmonton, Alberta T6G 2G2, Canada
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32
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Gandasi NR, Vestö K, Helou M, Yin P, Saras J, Barg S. Survey of Red Fluorescence Proteins as Markers for Secretory Granule Exocytosis. PLoS One 2015; 10:e0127801. [PMID: 26091288 PMCID: PMC4474633 DOI: 10.1371/journal.pone.0127801] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/18/2015] [Indexed: 12/18/2022] Open
Abstract
Fluorescent proteins (FPs) have proven to be valuable tools for high-resolution imaging studies of vesicle transport processes, including exo- and endocytosis. Since the pH of the vesicle lumen changes between acidic and neutral during these events, pH-sensitive FPs with near neutral pKa, such as pHluorin, are particularly useful. FPs with pKa>6 are readily available in the green spectrum, while red-emitting pH-sensitive FPs are rare and often not well characterized as reporters of exo- or endocytosis. Here we tested a panel of ten orange/red and two green FPs in fusions with neuropeptide Y (NPY) for use as secreted vesicle marker and reporter of dense core granule exocytosis and release. We report relative brightness, bleaching rate, targeting accuracy, sensitivity to vesicle pH, and their performance in detecting exocytosis in live cells. Tandem dimer (td)-mOrange2 was identified as well-targeted, bright, slowly bleaching and pH-sensitive FP that performed similar to EGFP. Single exocytosis events were readily observed, which allowed measurements of fusion pore lifetime and the dynamics of the exocytosis protein syntaxin at the release site during membrane fusion and cargo release.
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Affiliation(s)
- Nikhil R. Gandasi
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
| | - Kim Vestö
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
| | - Maria Helou
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
| | - Peng Yin
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
| | - Jan Saras
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
| | - Sebastian Barg
- Institute of Medical Cell Biology, Uppsala University, Box 571, Husargatan 3, 75123, Uppsala, Sweden
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33
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Labyntsev AI, Korotkevich NV, Manoĭlov KI, Kaberniuk AA, Kolibo DV, Komisarenko SV. [Recombinant fluorescent models for studying of diphtheria toxin]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2015; 40:433-42. [PMID: 25898753 DOI: 10.1134/s1068162014040086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Diphtheria toxin is the main pathogenicity factor of causative agent of diphtheria Corynebacterium diphtheriae. Due to the small molecule size, it is of considerable interestfor the development of synthetic protein molecules with transporting function, e.g. immunotoxins. Expression and characterization of nontoxic recombinant fluorescent derivates of diphtheria toxin and its nontoxic mutant CRM 197 were described in this article. Obtained proteins may be applied in studies of receptor-binding and transporting functions of the toxin in cells, for determination of toxin receptor proHB-EGF expression level, immunization and antibody generation against the toxin and in development of diagnostic test-systems, detection of diphtheria toxin and antitoxic antibodies.
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34
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Fan Y, Chen Z, Ai HW. Monitoring redox dynamics in living cells with a redox-sensitive red fluorescent protein. Anal Chem 2015; 87:2802-10. [PMID: 25666702 DOI: 10.1021/ac5041988] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Redox signaling and homeostasis are important for all forms of life on Earth. There has been great interest in monitoring redox dynamics in living cells and organisms as a mean to better understand redox biology in physiological and pathological conditions. Herein we report our recent results on the development of a genetically encoded redox-sensitive red fluorescent protein (rxRFP). We first identified a circularly permuted RFP (cpRFP) scaffold, which maintained its autocatalytic fluorescence, from a red fluorescent Ca(2+) sensor, R-GECO1. We then introduced cysteine residue pairs to the N- and C- termini of the cpRFP scaffold, and subsequently optimized the length and composition of the sequences adjacent to the cysteine residues. From these libraries, we identified rxRFP, showing up to a 4-fold fluorescence increase in the oxidized state compared to the reduced state at pH 7.4. We thoroughly characterized rxRFP in vitro, and expressed it in living mammalian cells to monitor redox dynamics. With its excitation peak at 576 nm and emission peak at 600 nm, rxRFP is one of the first genetically encoded red fluorescent probes that can sense general redox states.
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Affiliation(s)
- Yichong Fan
- Environmental Toxicology Graduate Program, University of California , Riverside, California 92521, United States
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35
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Nakamura S, Morimoto YV, Kudo S. A lactose fermentation product produced by Lactococcus lactis subsp. lactis, acetate, inhibits the motility of flagellated pathogenic bacteria. MICROBIOLOGY-SGM 2015; 161:701-7. [PMID: 25573770 DOI: 10.1099/mic.0.000031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/02/2015] [Indexed: 01/17/2023]
Abstract
Many strains of lactic acid bacteria have been used for the production of probiotics. Some metabolites produced by lactic acid bacteria impair the motilities of pathogenic bacteria. Because bacterial motility is strongly associated with virulence, the metabolic activities of lactic acid bacteria are effective for suppressing bacterial infections. Here we show that lactose fermentation by Lactococcus lactis subsp. lactis inhibits the motility of Salmonella enterica serovar Typhimurium. A single-cell tracking and rotation assay for a single flagellum showed that the swimming behaviour of Salmonella was severely but transiently impaired through disruption of flagellar rotation on exposure to media cultivated with Lac. lactis. Using a pH-sensitive fluorescent protein, we observed that the intracellular pH of Salmonella was decreased because of some fermentation products of Lac. lactis. We identified acetate as the lactose fermentation product of Lac. lactis triggering the paralysis of Salmonella flagella. The motilities of Pseudomonas, Vibrio and Leptospira strains were also severely disrupted by lactose utilization by Lac. lactis. These results highlight the potential use of Lac. lactis for preventing infections by multiple bacterial species.
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Affiliation(s)
- Shuichi Nakamura
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Yusuke V Morimoto
- Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan
| | - Seishi Kudo
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan
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36
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Shen Y, Rosendale M, Campbell RE, Perrais D. pHuji, a pH-sensitive red fluorescent protein for imaging of exo- and endocytosis. J Cell Biol 2014; 207:419-32. [PMID: 25385186 PMCID: PMC4226733 DOI: 10.1083/jcb.201404107] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Accepted: 10/07/2014] [Indexed: 11/22/2022] Open
Abstract
Fluorescent proteins with pH-sensitive fluorescence are valuable tools for the imaging of exocytosis and endocytosis. The Aequorea green fluorescent protein mutant superecliptic pHluorin (SEP) is particularly well suited to these applications. Here we describe pHuji, a red fluorescent protein with a pH sensitivity that approaches that of SEP, making it amenable for detection of single exocytosis and endocytosis events. To demonstrate the utility of the pHuji plus SEP pair, we perform simultaneous two-color imaging of clathrin-mediated internalization of both the transferrin receptor and the β2 adrenergic receptor. These experiments reveal that the two receptors are differentially sorted at the time of endocytic vesicle formation.
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Affiliation(s)
- Yi Shen
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Morgane Rosendale
- University of Bordeaux and Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France University of Bordeaux and Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
| | - Robert E Campbell
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - David Perrais
- University of Bordeaux and Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France University of Bordeaux and Centre National de la Recherche Scientifique, Interdisciplinary Institute for Neuroscience, UMR 5297, F-33000 Bordeaux, France
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37
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Benčina M. Illumination of the spatial order of intracellular pH by genetically encoded pH-sensitive sensors. SENSORS 2013; 13:16736-58. [PMID: 24316570 PMCID: PMC3892890 DOI: 10.3390/s131216736] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 11/27/2013] [Accepted: 11/27/2013] [Indexed: 12/11/2022]
Abstract
Fluorescent proteins have been extensively used for engineering genetically encoded sensors that can monitor levels of ions, enzyme activities, redox potential, and metabolites. Certain fluorescent proteins possess specific pH-dependent spectroscopic features, and thus can be used as indicators of intracellular pH. Moreover, concatenated pH-sensitive proteins with target proteins pin the pH sensors to a definite location within the cell, compartment, or tissue. This study provides an overview of the continually expanding family of pH-sensitive fluorescent proteins that have become essential tools for studies of pH homeostasis and cell physiology. We describe and discuss the design of intensity-based and ratiometric pH sensors, their spectral properties and pH-dependency, as well as their performance. Finally, we illustrate some examples of the applications of pH sensors targeted at different subcellular compartments.
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Affiliation(s)
- Mojca Benčina
- Laboratory of Biotechnology, National Institute of Chemistry, 1000 Ljubljana, Slovenia.
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38
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Satori CP, Henderson MM, Krautkramer EA, Kostal V, Distefano MM, Arriaga EA. Bioanalysis of eukaryotic organelles. Chem Rev 2013; 113:2733-811. [PMID: 23570618 PMCID: PMC3676536 DOI: 10.1021/cr300354g] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Chad P. Satori
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Michelle M. Henderson
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Elyse A. Krautkramer
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Vratislav Kostal
- Tescan, Libusina trida 21, Brno, 623 00, Czech Republic
- Institute of Analytical Chemistry ASCR, Veveri 97, Brno, 602 00, Czech Republic
| | - Mark M. Distefano
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
| | - Edgar A. Arriaga
- Department of Chemistry, University of Minnesota, Twin Cities, Minneapolis, MN, USA, 55455
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39
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Santo-Domingo J, Demaurex N. Perspectives on: SGP symposium on mitochondrial physiology and medicine: the renaissance of mitochondrial pH. ACTA ACUST UNITED AC 2013; 139:415-23. [PMID: 22641636 PMCID: PMC3362525 DOI: 10.1085/jgp.201110767] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Jaime Santo-Domingo
- Department of Cell Physiology and Metabolism, University of Geneva, CH-1211 Geneva, Switzerland
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40
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Shcherbakova DM, Subach OM, Verkhusha VV. Red fluorescent proteins: advanced imaging applications and future design. Angew Chem Int Ed Engl 2012; 51:10724-38. [PMID: 22851529 PMCID: PMC4433748 DOI: 10.1002/anie.201200408] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Indexed: 12/21/2022]
Abstract
In the past few years a large series of the advanced red-shifted fluorescent proteins (RFPs) has been developed. These enhanced RFPs provide new possibilities to study biological processes at the levels ranging from single molecules to whole organisms. Herein the relationship between the properties of the RFPs of different phenotypes and their applications to various imaging techniques are described. Existing and emerging imaging approaches are discussed for conventional RFPs, far-red FPs, RFPs with a large Stokes shift, fluorescent timers, irreversibly photoactivatable and reversibly photoswitchable RFPs. Advantages and limitations of specific RFPs for each technique are presented. Recent progress in understanding the chemical transformations of red chromophores allows the future RFP phenotypes and their respective novel imaging applications to be foreseen.
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Affiliation(s)
| | | | - Vladislav V. Verkhusha
- Department of Anatomy and Structural Biology and Gruss-Lipper, Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461 (USA)
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41
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Shcherbakova DM, Subach OM, Verkhusha VV. Rot fluoreszierende Proteine: spezielle Anwendungen in der Bildgebung und Perspektiven. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201200408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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42
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Li Y, Tsien RW. pHTomato, a red, genetically encoded indicator that enables multiplex interrogation of synaptic activity. Nat Neurosci 2012; 15:1047-53. [PMID: 22634730 PMCID: PMC3959862 DOI: 10.1038/nn.3126] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/30/2012] [Indexed: 11/08/2022]
Abstract
The usefulness of genetically encoded probes for optical monitoring of neuronal activity and brain circuits would be greatly advanced by the generation of multiple indicators with non-overlapping color spectra. Most existing indicators are derived from or spectrally convergent on GFP. We generated a bright, red, pH-sensitive fluorescent protein, pHTomato, that can be used in parallel with green probes to monitor neuronal activity. SypHTomato, made by fusing pHTomato to the vesicular membrane protein synaptophysin, reported activity-dependent exocytosis as efficiently as green reporters. When expressed with the GFP-based indicator GCaMP3 in the same neuron, sypHTomato enabled concomitant imaging of transmitter release and presynaptic Ca(2+) transients at single nerve terminals. Expressing sypHTomato and GCaMP3 in separate cells enabled the simultaneous determination of presynaptic vesicular turnover and postsynaptic sub- and supra-threshold responses from a connected pair of neurons. With these new tools, we observed a close size matching between pre- and postsynaptic compartments, as well as interesting target cell-dependent regulation of presynaptic vesicle pools. Lastly, by coupling expression of pHTomato- and GFP-based probes with distinct variants of channelrhodopsin, we provided proof-of-principle for an all-optical approach to multiplex control and tracking of distinct circuit pathways.
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Affiliation(s)
- Yulong Li
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Dr., Stanford, CA 94305, USA
| | - Richard W. Tsien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Dr., Stanford, CA 94305, USA
- NYU Neuroscience Institute and Department of Physiology and Neuroscience, New York University, New York, NY 10016, USA
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43
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Poburko D, Demaurex N. Regulation of the mitochondrial proton gradient by cytosolic Ca²⁺ signals. Pflugers Arch 2012; 464:19-26. [PMID: 22526460 DOI: 10.1007/s00424-012-1106-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 04/02/2012] [Indexed: 12/16/2022]
Abstract
Mitochondria convert the energy stored in carbohydrate and fat into ATP molecules that power enzymatic reactions within cells, and this process influences cellular calcium signals in several ways. By providing ATP to calcium pumps at the plasma and intracellular membranes, mitochondria power the calcium gradients that drive the release of Ca²⁺ from stores and the entry of Ca²⁺ across plasma membrane channels. By taking up and subsequently releasing calcium ions, mitochondria determine the spatiotemporal profile of cellular Ca²⁺ signals and the activity of Ca²⁺-regulated proteins, including Ca²⁺ entry channels that are themselves part of the Ca²⁺ circuitry. Ca²⁺ elevations in the mitochondrial matrix, in turn, activate Ca²⁺-dependent enzymes that boost the respiratory chain, increasing the ability of mitochondria to buffer calcium ions. Mitochondria are able to encode and decode Ca²⁺ signals because the respiratory chain generates an electrochemical gradient for protons across the inner mitochondrial membrane. This proton motive force (Δp) drives the activity of the ATP synthase and has both an electrical component, the mitochondrial membrane potential (ΔΨ(m)), and a chemical component, the mitochondrial proton gradient (ΔpH(m)). ΔΨ(m) contributes about 190 mV to Δp and drives the entry of Ca²⁺ across a recently identified Ca²⁺-selective channel known as the mitochondrial Ca²⁺ uniporter. ΔpH(m) contributes ~30 mV to Δp and is usually ignored or considered a minor component of mitochondria respiratory state. However, the mitochondrial proton gradient is an essential component of the chemiosmotic theory formulated by Peter Mitchell in 1961 as ΔpH(m) sustains the entry of substrates and metabolites required for the activity of the respiratory chain and drives the activity of electroneutral ion exchangers that allow mitochondria to maintain their osmolarity and volume. In this review, we summarize the mechanisms that regulate the mitochondrial proton gradient and discuss how thermodynamic concepts derived from measurements in purified mitochondria can be reconciled with our recent findings that mitochondria have high proton permeability in situ and that ΔpH(m) decreases during mitochondrial Ca²⁺ elevations.
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Affiliation(s)
- Damon Poburko
- Department of Biomedical Physiology & Kinesiology, Simon Fraser University, Vancouver, BC, Canada
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44
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Tantama M, Hung YP, Yellen G. Imaging intracellular pH in live cells with a genetically encoded red fluorescent protein sensor. J Am Chem Soc 2011; 133:10034-7. [PMID: 21631110 PMCID: PMC3126897 DOI: 10.1021/ja202902d] [Citation(s) in RCA: 308] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intracellular pH affects protein structure and function, and proton gradients underlie the function of organelles such as lysosomes and mitochondria. We engineered a genetically encoded pH sensor by mutagenesis of the red fluorescent protein mKeima, providing a new tool to image intracellular pH in live cells. This sensor, named pHRed, is the first ratiometric, single-protein red fluorescent sensor of pH. Fluorescence emission of pHRed peaks at 610 nm while exhibiting dual excitation peaks at 440 and 585 nm that can be used for ratiometric imaging. The intensity ratio responds with an apparent pK(a) of 6.6 and a >10-fold dynamic range. Furthermore, pHRed has a pH-responsive fluorescence lifetime that changes by ~0.4 ns over physiological pH values and can be monitored with single-wavelength two-photon excitation. After characterizing the sensor, we tested pHRed's ability to monitor intracellular pH by imaging energy-dependent changes in cytosolic and mitochondrial pH.
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Affiliation(s)
- Mathew Tantama
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA
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45
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Johnson DE, Casey JR. Cytosolic H+ microdomain developed around AE1 during AE1-mediated Cl-/HCO3- exchange. J Physiol 2011; 589:1551-69. [PMID: 21300752 DOI: 10.1113/jphysiol.2010.201483] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Microdomains, regions of discontinuous cytosolic solute concentration enhanced by rapid solute transport and slow diffusion rates, have many cellular roles. pH-regulatory membrane transporters, like the Cl−/HCO3− exchanger AE1, could develop H+ microdomains since AE1 has a rapid transport rate and cytosolic H+ diffusion is slow. We examined whether the pH environment surrounding AE1 differs from other cellular locations. As AE1 drives Cl−/HCO3− exchange, differences in pH, near and remote from AE1, were monitored by confocal microscopy using two pH-sensitive fluorescent proteins: deGFP4 (GFP) and mNectarine (mNect). Plasma membrane (PM) pH (defined as ∼1 μm region around the cell periphery) was monitored by GFP fused to AE1 (GFP.AE1), and mNect fused to an inactive mutant of the Na+-coupled nucleoside co-transporter, hCNT3 (mNect.hCNT3). GFP.AE1 to mNect.hCNT3 distance was varied by co-expression of different amounts of the two proteins in HEK293 cells. As the GFP.AE1–mNect.hCNT3 distance increased, mNect.hCNT3 detected the Cl−/HCO3− exchange-associated cytosolic pH change with a time delay and reduced rate of pH change compared to GFP.AE1. We found that a H+ microdomain 0.3 μm in diameter forms around GFP.AE1 during physiological HCO3− transport. Carbonic anhydrase isoform II inhibition prevented H+ microdomain formation. We also measured the rate of H+ movement from PM GFP.AE1 to endoplasmic reticulum (ER), using mNect fused to the cytosolic face of ER-resident calnexin (CNX.mNect). The rate of H+ diffusion through cytosol was 60-fold faster than along the cytosolic surface of the plasma membrane. The pH environment surrounding pH regulatory transport proteins may differ as a result of H+ microdomain formation, which will affect nearby pH-sensitive processes.
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Affiliation(s)
- Danielle E Johnson
- Membrane Protein Research Group, Department of Physiology, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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46
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Abstract
Since the discovery of the first red fluorescent protein (RFP), named DsRed, 12 years ago, a wide pallet of red-shifted fluorescent proteins has been cloned and biotechnologically developed into monomeric fluorescent probes for optical microscopy. Several new types of monomeric RFPs that change the emission wavelength either with time, called fluorescent timers, or after a brief irradiation with violet light, known as photoactivatable proteins, have been also engineered. Moreover, RFPs with a large Stokes shift of fluorescence emission have been recently designed. Because of their distinctive excitation and fluorescence detection conditions developed specifically for microscopy, these fluorescent probes can be suboptimal for flow cytometry. Here, we have selected and summarized the advanced orange, red, and far-red fluorescent proteins with the properties specifically required for the flow cytometry applications. Their effective brightness was calculated for the laser sources available for the commercial flow cytometers and sorters. Compatibility of the fluorescent proteins of different colors in a multiparameter flow cytometry was determined. Novel FRET pairs, utilizing RFPs, RFP-based intracellular biosensors, and their application to a high-throughput screening, are also discussed.
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Affiliation(s)
- Kiryl D Piatkevich
- Department of Anatomy and Structural Biology, and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York, USA
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47
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Möhlmann T, Bernard C, Hach S, Ekkehard Neuhaus H. Nucleoside transport and associated metabolism. PLANT BIOLOGY (STUTTGART, GERMANY) 2010; 12 Suppl 1:26-34. [PMID: 20712618 DOI: 10.1111/j.1438-8677.2010.00351.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nucleosides are intermediates of nucleotide metabolism. Nucleotide de novo synthesis generates the nucleoside monophosphates AMP and UMP, which are further processed to all purine and pyrimidine nucleotides involved in multiple cellular reactions, including the synthesis of nucleic acids. Catabolism of these substances results in the formation of nucleosides, which are further degraded by nucleoside hydrolase to nucleobases. Both nucleosides and nucleobases can be exchanged between cells and tissues through multiple isoforms of corresponding transport proteins. After uptake into a cell, nucleosides and nucleobases can undergo salvage reactions or catabolism. Whereas energy is preserved by salvage pathway reactions, catabolism liberates ammonia, which is then incorporated into amino acids. Keeping the balance between nitrogen consumption during nucleotide de novo synthesis and ammonia liberation by nucleotide catabolism is essential for correct plant development. Senescence and seed germination represent situations in plant development where marked fluctuations in nucleotide pools occur. Furthermore, extracellular nucleotide metabolism has become an immensely interesting research topic. In addition, selected aspects of nucleoside transport in yeast, protists and humans are discussed.
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Affiliation(s)
- T Möhlmann
- Abteilung Pflanzenphysiologie, Fachbereich Biologie, Technische Universität Kaiserslautern, Kaiserslautern, Germany.
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48
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Chudakov DM, Matz MV, Lukyanov S, Lukyanov KA. Fluorescent proteins and their applications in imaging living cells and tissues. Physiol Rev 2010; 90:1103-63. [PMID: 20664080 DOI: 10.1152/physrev.00038.2009] [Citation(s) in RCA: 915] [Impact Index Per Article: 65.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Green fluorescent protein (GFP) from the jellyfish Aequorea victoria and its homologs from diverse marine animals are widely used as universal genetically encoded fluorescent labels. Many laboratories have focused their efforts on identification and development of fluorescent proteins with novel characteristics and enhanced properties, resulting in a powerful toolkit for visualization of structural organization and dynamic processes in living cells and organisms. The diversity of currently available fluorescent proteins covers nearly the entire visible spectrum, providing numerous alternative possibilities for multicolor labeling and studies of protein interactions. Photoactivatable fluorescent proteins enable tracking of photolabeled molecules and cells in space and time and can also be used for super-resolution imaging. Genetically encoded sensors make it possible to monitor the activity of enzymes and the concentrations of various analytes. Fast-maturing fluorescent proteins, cell clocks, and timers further expand the options for real time studies in living tissues. Here we focus on the structure, evolution, and function of GFP-like proteins and their numerous applications for in vivo imaging, with particular attention to recent techniques.
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49
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Carlson HJ, Cotton DW, Campbell RE. Circularly permuted monomeric red fluorescent proteins with new termini in the beta-sheet. Protein Sci 2010; 19:1490-9. [PMID: 20521333 PMCID: PMC2923502 DOI: 10.1002/pro.428] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 05/18/2010] [Indexed: 11/10/2022]
Abstract
Circularly permuted fluorescent proteins (FPs) have a growing number of uses in live cell fluorescence biosensing applications. Most notably, they enable the construction of single fluorescent protein-based biosensors for Ca(2+) and other analytes of interest. Circularly permuted FPs are also of great utility in the optimization of fluorescence resonance energy transfer (FRET)-based biosensors by providing a means for varying the critical dipole-dipole orientation. We have previously reported on our efforts to create circularly permuted variants of a monomeric red FP (RFP) known as mCherry. In our previous work, we had identified six distinct locations within mCherry that tolerated the insertion of a short peptide sequence. Creation of circularly permuted variants with new termini at the locations corresponding to the sites of insertion led to the discovery of three permuted variants that retained no more than 18% of the brightness of mCherry. We now report the extensive directed evolution of the variant with new termini at position 193 of the protein sequence for improved fluorescent brightness. The resulting variant, known as cp193g7, has 61% of the intrinsic brightness of mCherry and was found to be highly tolerant of circular permutation at other locations within the sequence. We have exploited this property to engineer an expanded series of circularly permuted variants with new termini located along the length of the 10th beta-strand of mCherry. These new variants may ultimately prove useful for the creation of single FP-based Ca(2+) biosensors.
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Affiliation(s)
| | | | - Robert E Campbell
- Department of Chemistry, University of AlbertaEdmonton, Alberta, Canada T6G 2G2
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50
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Effects of Na+ and H+ on steady-state and presteady-state currents of the human concentrative nucleoside transporter 3 (hCNT3). Pflugers Arch 2010; 460:617-32. [DOI: 10.1007/s00424-010-0846-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Revised: 04/13/2010] [Accepted: 05/04/2010] [Indexed: 11/26/2022]
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