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Role of membrane mimetics on biophysical EPR studies of membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184138. [PMID: 36764474 DOI: 10.1016/j.bbamem.2023.184138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 02/11/2023]
Abstract
Biological membranes are essential in providing the stability of membrane proteins in a functional state. Functionally stable homogeneous sample is required for biophysical electron paramagnetic resonance (EPR) studies of membrane proteins for obtaining pertinent structural dynamics of the protein. Significant progresses have been made for the optimization of the suitable membrane environments required for biophysical EPR measurements. However, no universal membrane mimetic system is available that can solubilize all membrane proteins suitable for biophysical EPR studies while maintaining the functional integrity. Great efforts are needed to optimize the sample condition to obtain better EPR data quality of membrane proteins that can provide meaningful information on structural dynamics. In this mini-review, we will discuss important aspects of membrane mimetics for biophysical EPR measurements and current progress with some of the recent examples.
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Pedersen GB, Blaschek L, Frandsen KEH, Noack LC, Persson S. Cellulose synthesis in land plants. MOLECULAR PLANT 2023; 16:206-231. [PMID: 36564945 DOI: 10.1016/j.molp.2022.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
All plant cells are surrounded by a cell wall that provides cohesion, protection, and a means of directional growth to plants. Cellulose microfibrils contribute the main biomechanical scaffold for most of these walls. The biosynthesis of cellulose, which typically is the most prominent constituent of the cell wall and therefore Earth's most abundant biopolymer, is finely attuned to developmental and environmental cues. Our understanding of the machinery that catalyzes and regulates cellulose biosynthesis has substantially improved due to recent technological advances in, for example, structural biology and microscopy. Here, we provide a comprehensive overview of the structure, function, and regulation of the cellulose synthesis machinery and its regulatory interactors. We aim to highlight important knowledge gaps in the field, and outline emerging approaches that promise a means to close those gaps.
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Affiliation(s)
- Gustav B Pedersen
- Copenhagen Plant Science Center (CPSC), Department of Plant & Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark
| | - Leonard Blaschek
- Copenhagen Plant Science Center (CPSC), Department of Plant & Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark
| | - Kristian E H Frandsen
- Copenhagen Plant Science Center (CPSC), Department of Plant & Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark
| | - Lise C Noack
- Copenhagen Plant Science Center (CPSC), Department of Plant & Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark
| | - Staffan Persson
- Copenhagen Plant Science Center (CPSC), Department of Plant & Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark; Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, SJTU-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
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Georgieva E, Karamalakova Y, Arabadzhiev G, Atanasov V, Kostandieva R, Mitev M, Tsoneva V, Yovchev Y, Nikolova G. Site-Directed Spin Labeling EPR Spectroscopy for Determination of Albumin Structural Damage and Hypoalbuminemia in Critical COVID-19. Antioxidants (Basel) 2022; 11:antiox11122311. [PMID: 36552520 PMCID: PMC9774111 DOI: 10.3390/antiox11122311] [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: 10/07/2022] [Revised: 11/17/2022] [Accepted: 11/20/2022] [Indexed: 11/24/2022] Open
Abstract
The main factors in the COVID-19 pathology, which can initiate extensive structural changes at the cellular and molecular levels, are the generation of free radicals in abnormal amounts, and oxidative stress. Under "oxidative shock" conditions, the proteins undergo various modifications that affect their function and activity, and as a result distribute malfunctioning protein derivatives in the body. Human serum albumin is a small globular protein characterized by a high overall binding capacity for neutral lipophilic and acidic dosage forms. The albumin concentration is crucial for the maintenance of plasma oncotic pressure, the transport of nutrients, amino acids, and drugs, the effectiveness of drug therapy, and the prevention of drug toxicity. Hypoalbuminemia and structural defects molecule in the protein suggest a risk of changed metabolism and increased plasma concentration of unbound drugs. Therefore, the albumin structural and functional changes accompanied by low protein levels can be a serious prerequisite for ineffective therapy, frequent complications, and high mortality in patients with SARS-CoV-2 infection. The current opinion aims the research community the application of Site-Directed Spin Labeling Electron Paramagnetic Resonance spectroscopy (SDSL-EPR) and 3-Maleimido-PROXYL radical in determining abnormalities of the albumin dynamics and protein concentrations in COVID-19 critical patients.
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Affiliation(s)
- Ekaterina Georgieva
- Department of “General and Clinical Pathology, Forensic Medicine, Deontology and Dermatovenerology”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Yanka Karamalakova
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Georgi Arabadzhiev
- Department of “Surgery and Anesthesiology”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Vasil Atanasov
- Forensic Toxicology Laboratory, Military Medical Academy, 3 “Sv. Georgi Sofiiski Str.”, 1606 Sofia, Bulgaria
| | - Rositsa Kostandieva
- Forensic Toxicology Laboratory, Military Medical Academy, 3 “Sv. Georgi Sofiiski Str.”, 1606 Sofia, Bulgaria
| | - Mitko Mitev
- Department of “Diagnostic Imaging”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Vanya Tsoneva
- Department of Propaedeutics of Internal Medicine and Clinical Laboratory, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
| | - Yovcho Yovchev
- Department of “Surgery and Anesthesiology”, University Hospital “Prof. Dr. St. Kirkovich”, 6000 Stara Zagora, Bulgaria
| | - Galina Nikolova
- Department of “Medical Chemistry and Biochemistry”, Medical Faculty, Trakia University, 11 Armeiska Str., 6000 Stara Zagora, Bulgaria
- Correspondence: ; Tel.: +359-897771301
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Abhyankar N, Agrawal A, Campbell J, Maly T, Shrestha P, Szalai V. Recent advances in microresonators and supporting instrumentation for electron paramagnetic resonance spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:101101. [PMID: 36319314 PMCID: PMC9632321 DOI: 10.1063/5.0097853] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/13/2022] [Indexed: 06/16/2023]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy characterizes the magnetic properties of paramagnetic materials at the atomic and molecular levels. Resonators are an enabling technology of EPR spectroscopy. Microresonators, which are miniaturized versions of resonators, have advanced inductive-detection EPR spectroscopy of mass-limited samples. Here, we provide our perspective of the benefits and challenges associated with microresonator use for EPR spectroscopy. To begin, we classify the application space for microresonators and present the conceptual foundation for analysis of resonator sensitivity. We summarize previous work and provide insight into the design and fabrication of microresonators as well as detail the requirements and challenges that arise in incorporating microresonators into EPR spectrometer systems. Finally, we provide our perspective on current challenges and prospective fruitful directions.
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Affiliation(s)
| | - Amit Agrawal
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Jason Campbell
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Thorsten Maly
- Bridge12 Technologies, Inc., Natick, Massachusetts 01760, USA
| | | | - Veronika Szalai
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Campbell C, Faleel FDM, Scheyer MW, Haralu S, Williams PL, Carbo WD, Wilson-Taylor AS, Patel NH, Sanders CR, Lorigan GA, Sahu ID. Comparing the structural dynamics of the human KCNE3 in reconstituted micelle and lipid bilayered vesicle environments. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183974. [PMID: 35716725 DOI: 10.1016/j.bbamem.2022.183974] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 05/12/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
KCNE3 is a single transmembrane protein of the KCNE family that modulates the function and trafficking of several voltage-gated potassium channels, including KCNQ1. Structural studies of KCNE3 have been previously conducted in a wide range of model membrane mimics. However, it is important to assess the impact of the membrane mimics used on the observed conformation and dynamics. In this study, we have optimized a method for the reconstitution of the KCNE3 into POPC/POPG lipid bilayer vesicles for electron paramagnetic resonance (EPR) spectroscopy. Our CD spectroscopic data suggested that the degree of regular secondary structure for KCNE3 protein reconstituted into lipid bilayered vesicle is significantly higher than in DPC detergent micelles. Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) was used to probe the structural dynamics of S49C, M59C, L67C, V85C, and S101C mutations of KCNE3 in both DPC micelles and in POPC/POPG lipid bilayered vesicles. Our CW-EPR power saturation data suggested that the site S74C is buried inside the lipid bilayered membrane while the site V85C is located outside the membrane, in contrast to DPC micelle results. These results suggest that the KCNE3 micelle structures need to be refined using data obtained in the lipid bilayered vesicles in order to ascertain the native structure of KCNE3. This work will provide guidelines for detailed structural studies of KCNE3 in a more native membrane environment and comparing the lipid bilayer results to the isotropic bicelle structure and to the KCNQ1-bound cryo-EM structure.
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Affiliation(s)
- Conner Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | | | - Matthew W Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Samuel Haralu
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Patrick L Williams
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - William David Carbo
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | | | - Nima H Patel
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN, United States of America
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, United States of America
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America; Department of Chemistry and Biochemistry, Miami University, Oxford, OH, United States of America.
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Bartucci R, Aloi E. Librational Dynamics of Spin-Labeled Membranes at Cryogenic Temperatures From Echo-Detected ED-EPR Spectra. Front Mol Biosci 2022; 9:923794. [PMID: 35847982 PMCID: PMC9277068 DOI: 10.3389/fmolb.2022.923794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 05/19/2022] [Indexed: 11/13/2022] Open
Abstract
Methods of electron spin echo of pulse electron paramagnetic resonance (EPR) spectroscopy are increasingly employed to investigate biophysical properties of nitroxide-labeled biosystems at cryogenic temperatures. Two-pulse echo-detected ED-spectra have proven to be valuable tools to describe the librational dynamics in the low-temperature phases of both lipids and proteins in membranes. The motional parameter, α2τC, given by the product of the mean-square angular amplitude, α2, and the rotational correlation time, τC, of the motion, is readily determined from the nitroxide ED-spectra as well as from the W-relaxation rate curves. An independent evaluation of α2 is obtained from the motionally averaged 14N-hyperfine splitting separation in the continuous wave cw-EPR spectra. Finally, the rotational correlation time τC can be estimated by combining ED- and cw-EPR data. In this mini-review, results on the librational dynamics in model and natural membranes are illustrated.
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Affiliation(s)
- Rosa Bartucci
- Department of Chemistry and Chemical Technologies, University of Calabria, Rende (CS), Italy
- *Correspondence: Rosa Bartucci,
| | - Erika Aloi
- Molecular Biophysics Laboratory, Department of Physics, University of Calabria, Rende (CS), Italy
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Kugele A, Ketter S, Silkenath B, Wittmann V, Joseph B, Drescher M. In situ EPR spectroscopy of a bacterial membrane transporter using an expanded genetic code. Chem Commun (Camb) 2021; 57:12980-12983. [PMID: 34792069 PMCID: PMC8640571 DOI: 10.1039/d1cc04612h] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/03/2021] [Indexed: 12/12/2022]
Abstract
The membrane transporter BtuB is site-directedly spin labelled on the surface of living Escherichia coli via Diels-Alder click chemistry of the genetically encoded amino acid SCO-L-lysine. The previously introduced photoactivatable nitroxide PaNDA prevents off-target labelling, is used for distance measurements, and the temporally shifted activation of the nitroxide allows for advanced experimental setups. This study describes significant evolution of Diels-Alder-mediated spin labelling on cellular surfaces and opens up new vistas for the the study of membrane proteins.
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Affiliation(s)
- Anandi Kugele
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
| | - Sophie Ketter
- Institute of Biophysics, Department of Physics & The Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany.
| | - Bjarne Silkenath
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
| | - Valentin Wittmann
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
| | - Benesh Joseph
- Institute of Biophysics, Department of Physics & The Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany.
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.
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