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Berg AE, Velayuthan LP, Månsson A, Ušaj M. Cost-Efficient Expression of Human Cardiac Myosin Heavy Chain in C2C12 Cells with a Non-Viral Transfection Reagent. Int J Mol Sci 2024; 25:6747. [PMID: 38928453 PMCID: PMC11203843 DOI: 10.3390/ijms25126747] [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: 05/06/2024] [Revised: 06/14/2024] [Accepted: 06/17/2024] [Indexed: 06/28/2024] Open
Abstract
Production of functional myosin heavy chain (MHC) of striated muscle myosin II for studies of isolated proteins requires mature muscle (e.g., C2C12) cells for expression. This is important both for fundamental studies of molecular mechanisms and for investigations of deleterious diseases like cardiomyopathies due to mutations in the MHC gene (MYH7). Generally, an adenovirus vector is used for transfection, but recently we demonstrated transfection by a non-viral polymer reagent, JetPrime. Due to the rather high costs of JetPrime and for the sustainability of the virus-free expression method, access to more than one transfection reagent is important. Here, we therefore evaluate such a candidate substance, GenJet. Using the human cardiac β-myosin heavy chain (β-MHC) as a model system, we found effective transfection of C2C12 cells showing a transfection efficiency nearly as good as with the JetPrime reagent. This was achieved following a protocol developed for JetPrime because a manufacturer-recommended application protocol for GenJet to transfect cells in suspension did not perform well. We demonstrate, using in vitro motility assays and single-molecule ATP turnover assays, that the protein expressed and purified from cells transfected with the GenJet reagent is functional. The purification yields reached were slightly lower than in JetPrime-based purifications, but they were achieved at a significantly lower cost. Our results demonstrate the sustainability of the virus-free method by showing that more than one polymer-based transfection reagent can generate useful amounts of active MHC. Particularly, we suggest that GenJet, due to its current ~4-fold lower cost, is useful for applications requiring larger amounts of a given MHC variant.
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Affiliation(s)
| | | | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, 391 82 Kalmar, Sweden; (A.E.B.); (L.P.V.)
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, 391 82 Kalmar, Sweden; (A.E.B.); (L.P.V.)
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2
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Berg A, Velayuthan LP, Tågerud S, Ušaj M, Månsson A. Probing actin-activated ATP turnover kinetics of human cardiac myosin II by single molecule fluorescence. Cytoskeleton (Hoboken) 2024. [PMID: 38623952 DOI: 10.1002/cm.21858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/06/2024] [Accepted: 03/25/2024] [Indexed: 04/17/2024]
Abstract
Mechanistic insights into myosin II energy transduction in striated muscle in health and disease would benefit from functional studies of a wide range of point-mutants. This approach is, however, hampered by the slow turnaround of myosin II expression that usually relies on adenoviruses for gene transfer. A recently developed virus-free method is more time effective but would yield too small amounts of myosin for standard biochemical analyses. However, if the fluorescent adenosine triphosphate (ATP) and single molecule (sm) total internal reflection fluorescence microscopy previously used to analyze basal ATP turnover by myosin alone, can be expanded to actin-activated ATP turnover, it would appreciably reduce the required amount of myosin. To that end, we here describe zero-length cross-linking of human cardiac myosin II motor fragments (sub-fragment 1 long [S1L]) to surface-immobilized actin filaments in a configuration with maintained actin-activated ATP turnover. After optimizing the analysis of sm fluorescence events, we show that the amount of myosin produced from C2C12 cells in one 60 mm cell culture plate is sufficient to obtain both the basal myosin ATP turnover rate and the maximum actin-activated rate constant (kcat). Our analysis of many single binding events of fluorescent ATP to many S1L motor fragments revealed processes reflecting basal and actin-activated ATPase, but also a third exponential process consistent with non-specific ATP-binding outside the active site.
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Affiliation(s)
- Albin Berg
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Science, Linnaeus University, Kalmar, Sweden
| | - Lok Priya Velayuthan
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Science, Linnaeus University, Kalmar, Sweden
| | - Sven Tågerud
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Science, Linnaeus University, Kalmar, Sweden
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Science, Linnaeus University, Kalmar, Sweden
| | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Science, Linnaeus University, Kalmar, Sweden
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3
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Månsson A, Ušaj M, Moretto L, Matusovsky O, Velayuthan LP, Friedman R, Rassier DE. New paradigms in actomyosin energy transduction: Critical evaluation of non-traditional models for orthophosphate release. Bioessays 2023; 45:e2300040. [PMID: 37366639 DOI: 10.1002/bies.202300040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/28/2023]
Abstract
Release of the ATP hydrolysis product ortophosphate (Pi) from the active site of myosin is central in chemo-mechanical energy transduction and closely associated with the main force-generating structural change, the power-stroke. Despite intense investigations, the relative timing between Pi-release and the power-stroke remains poorly understood. This hampers in depth understanding of force production by myosin in health and disease and our understanding of myosin-active drugs. Since the 1990s and up to today, models that incorporate the Pi-release either distinctly before or after the power-stroke, in unbranched kinetic schemes, have dominated the literature. However, in recent years, alternative models have emerged to explain apparently contradictory findings. Here, we first compare and critically analyze three influential alternative models proposed previously. These are either characterized by a branched kinetic scheme or by partial uncoupling of Pi-release and the power-stroke. Finally, we suggest critical tests of the models aiming for a unified picture.
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Affiliation(s)
- Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Luisa Moretto
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Oleg Matusovsky
- Department of Kinesiology and Physical Education, McGill University, Montreal, Québec, Canada
| | - Lok Priya Velayuthan
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Ran Friedman
- Department of Chemistry and Biomedical Sciences, Linnaeus University, Kalmar, Sweden
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Québec, Canada
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4
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Multistep orthophosphate release tunes actomyosin energy transduction. Nat Commun 2022; 13:4575. [PMID: 35931685 PMCID: PMC9356070 DOI: 10.1038/s41467-022-32110-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 07/13/2022] [Indexed: 11/29/2022] Open
Abstract
Muscle contraction and a range of critical cellular functions rely on force-producing interactions between myosin motors and actin filaments, powered by turnover of adenosine triphosphate (ATP). The relationship between release of the ATP hydrolysis product ortophosphate (Pi) from the myosin active site and the force-generating structural change, the power-stroke, remains enigmatic despite its central role in energy transduction. Here, we present a model with multistep Pi-release that unifies current conflicting views while also revealing additional complexities of potential functional importance. The model is based on our evidence from kinetics, molecular modelling and single molecule fluorescence studies of Pi binding outside the active site. It is also consistent with high-speed atomic force microscopy movies of single myosin II molecules without Pi at the active site, showing consecutive snapshots of pre- and post-power stroke conformations. In addition to revealing critical features of energy transduction by actomyosin, the results suggest enzymatic mechanisms of potentially general relevance. Release of the ATP hydrolysis product orthophosphate (Pi) from the myosin active site is central in force generation but is poorly understood. Here, Moretto et al. present evidence for multistep Pi-release reconciling apparently contradictory results.
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Ušaj M, Moretto L, Vemula V, Salhotra A, Månsson A. Single molecule turnover of fluorescent ATP by myosin and actomyosin unveil elusive enzymatic mechanisms. Commun Biol 2021; 4:64. [PMID: 33441912 PMCID: PMC7806905 DOI: 10.1038/s42003-020-01574-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 12/04/2020] [Indexed: 01/10/2023] Open
Abstract
Benefits of single molecule studies of biomolecules include the need for minimal amounts of material and the potential to reveal phenomena hidden in ensembles. However, results from recent single molecule studies of fluorescent ATP turnover by myosin are difficult to reconcile with ensemble studies. We found that key reasons are complexities due to dye photophysics and fluorescent contaminants. After eliminating these, through surface cleaning and use of triple state quenchers and redox agents, the distributions of ATP binding dwell times on myosin are best described by 2 to 3 exponential processes, with and without actin, and with and without the inhibitor para-aminoblebbistatin. Two processes are attributable to ATP turnover by myosin and actomyosin respectively, whereas the remaining process (rate constant 0.2–0.5 s−1) is consistent with non-specific ATP binding to myosin, possibly accelerating ATP transport to the active site. Finally, our study of actin-activated myosin ATP turnover without sliding between actin and myosin reveals heterogeneity in the ATP turnover kinetics consistent with models of isometric contraction. With fluorescence based-TIRF microspectroscopy, Ušaj et al. unveil mechanistic details about the ATP turnover rates by myosin and actomyosin with enzymatic reaction pathways that were not possible to obtain from ensemble studies. This study could be important to the field of molecular motors.
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Affiliation(s)
- Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE391 82, Kalmar, Sweden.
| | - Luisa Moretto
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE391 82, Kalmar, Sweden
| | - Venukumar Vemula
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE391 82, Kalmar, Sweden
| | - Aseem Salhotra
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE391 82, Kalmar, Sweden
| | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, SE391 82, Kalmar, Sweden.
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Rockenfeller R, Günther M, Stutzig N, Haeufle DFB, Siebert T, Schmitt S, Leichsenring K, Böl M, Götz T. Exhaustion of Skeletal Muscle Fibers Within Seconds: Incorporating Phosphate Kinetics Into a Hill-Type Model. Front Physiol 2020; 11:306. [PMID: 32431619 PMCID: PMC7214688 DOI: 10.3389/fphys.2020.00306] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 03/19/2020] [Indexed: 12/01/2022] Open
Abstract
Initiated by neural impulses and subsequent calcium release, skeletal muscle fibers contract (actively generate force) as a result of repetitive power strokes of acto-myosin cross-bridges. The energy required for performing these cross-bridge cycles is provided by the hydrolysis of adenosine triphosphate (ATP). The reaction products, adenosine diphosphate (ADP) and inorganic phosphate (P i ), are then used-among other reactants, such as creatine phosphate-to refuel the ATP energy storage. However, similar to yeasts that perish at the hands of their own waste, the hydrolysis reaction products diminish the chemical potential of ATP and thus inhibit the muscle's force generation as their concentration rises. We suggest to use the term "exhaustion" for force reduction (fatigue) that is caused by combined P i and ADP accumulation along with a possible reduction in ATP concentration. On the basis of bio-chemical kinetics, we present a model of muscle fiber exhaustion based on hydrolytic ATP-ADP-P i dynamics, which are assumed to be length- and calcium activity-dependent. Written in terms of differential-algebraic equations, the new sub-model allows to enhance existing Hill-type excitation-contraction models in a straightforward way. Measured time courses of force decay during isometric contractions of rabbit M. gastrocnemius and M. plantaris were employed for model verification, with the finding that our suggested model enhancement proved eminently promising. We discuss implications of our model approach for enhancing muscle models in general, as well as a few aspects regarding the significance of phosphate kinetics as one contributor to muscle fatigue.
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Affiliation(s)
| | - Michael Günther
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
- Friedrich-Schiller-University, Jena, Germany
| | - Norman Stutzig
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Daniel F. B. Haeufle
- Hertie-Institute for Clinical Brain Research and Center for Integrative Neuroscience, Eberhard-Karls-University, Tübingen, Germany
| | - Tobias Siebert
- Department of Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Syn Schmitt
- Institute for Modelling and Simulation of Biomechanical Systems, Computational Biophysics and Biorobotics, University of Stuttgart, Stuttgart, Germany
| | - Kay Leichsenring
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Markus Böl
- Institute of Solid Mechanics, Technical University Braunschweig, Braunschweig, Germany
| | - Thomas Götz
- Mathematical Institute, University of Koblenz-Landau, Koblenz, Germany
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7
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Fujita K, Ohmachi M, Ikezaki K, Yanagida T, Iwaki M. Direct visualization of human myosin II force generation using DNA origami-based thick filaments. Commun Biol 2019; 2:437. [PMID: 31799438 PMCID: PMC6881340 DOI: 10.1038/s42003-019-0683-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 11/07/2019] [Indexed: 11/08/2022] Open
Abstract
The sarcomere, the minimal mechanical unit of muscle, is composed of myosins, which self-assemble into thick filaments that interact with actin-based thin filaments in a highly-structured lattice. This complex imposes a geometric restriction on myosin in force generation. However, how single myosins generate force within the restriction remains elusive and conventional synthetic filaments do not recapitulate the symmetric bipolar filaments in sarcomeres. Here we engineered thick filaments using DNA origami that incorporate human muscle myosin to directly visualize the motion of the heads during force generation in a restricted space. We found that when the head diffuses, it weakly interacts with actin filaments and then strongly binds preferentially to the forward region as a Brownian ratchet. Upon strong binding, the two-step lever-arm swing dominantly halts at the first step and occasionally reverses direction. Our results illustrate the usefulness of our DNA origami-based assay system to dissect the mechanistic details of motor proteins.
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Affiliation(s)
- Keisuke Fujita
- RIKEN Center for Biosystems Dynamics Research, RIKEN, Osaka, Japan
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Masashi Ohmachi
- RIKEN Center for Biosystems Dynamics Research, RIKEN, Osaka, Japan
| | | | - Toshio Yanagida
- RIKEN Center for Biosystems Dynamics Research, RIKEN, Osaka, Japan
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Center for Information and Neural Networks, NICT, Osaka, Japan
| | - Mitsuhiro Iwaki
- RIKEN Center for Biosystems Dynamics Research, RIKEN, Osaka, Japan
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- AMED-PRIME, Japan Agency for Medical Research and Development, Tokyo, Japan
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8
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Amrute-Nayak M, Nayak A, Steffen W, Tsiavaliaris G, Scholz T, Brenner B. Transformation of the Nonprocessive Fast Skeletal Myosin II into a Processive Motor. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804313. [PMID: 30657637 DOI: 10.1002/smll.201804313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/02/2019] [Indexed: 06/09/2023]
Abstract
Myosin family motors play diverse cellular roles. Precise insights into how the light chains contribute to the functional variabilities among myosin motors, however, remain unresolved. Here, it is demonstrated that the fast skeletal muscle myosin II isoform myosin heavy chain (MHC-IID) can be transformed into a processive motor, by simply replacing the native regulatory light chain MLC2f with the regulatory light chain variant MLC2v from the slow muscle myosin II. Single molecule kinetic analyses and optical trapping measurements of the hybrid motor reveal marked changes such as increased association rate of myosin toward adenosine triphosphate (ATP) and actin by more than twofold. The direct consequence of high adenosine diphosphate (ADP) affinity and increased actin rebinding is the altered overall actomyosin association time during the cross-bridge cycle. The data indicate that the MLC2v influences the duty ratio in the hybrid motor, suggestive of promoting interhead communication and enabling processive movement. This finding establishes that the regulatory light chain fine-tunes the motor's mechanical output that may have important implications under physiological conditions. Furthermore, the success of this approach paves the way to engineer motors from a known motor protein element to assemble highly specialized biohybrid machines for potential applications in nano-biomedicine and engineering.
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Affiliation(s)
- Mamta Amrute-Nayak
- Institute of Molecular and Cell Physiology, Hannover Medical School, D-30625, Hannover, Germany
| | - Arnab Nayak
- Institute of Molecular and Cell Physiology, Hannover Medical School, D-30625, Hannover, Germany
| | - Walter Steffen
- Institute of Molecular and Cell Physiology, Hannover Medical School, D-30625, Hannover, Germany
| | - Georgios Tsiavaliaris
- Institute of Biophysical Chemistry, Hannover Medical School, D-30625, Hannover, Germany
| | - Tim Scholz
- Institute of Molecular and Cell Physiology, Hannover Medical School, D-30625, Hannover, Germany
| | - Bernhard Brenner
- Institute of Molecular and Cell Physiology, Hannover Medical School, D-30625, Hannover, Germany
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9
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Tesi C, Barman T, Lionne C. Are there two different binding sites for ATP on the myosin head, or only one that switches between two conformers? J Muscle Res Cell Motil 2019; 38:137-142. [PMID: 28905159 DOI: 10.1007/s10974-017-9480-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chiara Tesi
- Division of Physiology, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
| | - Tom Barman
- U128, 8 rue Dom Vaissette, Montpellier, France
| | - Corinne Lionne
- Centre de Biochimie Structurale (CBS), INSERM, CNRS, Université de Montpellier, Montpellier, France.
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10
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Chattoraj S, Saha S, Halder D, Jana SS, Bhattacharyya K. Structural Oscillations of Non-muscle Myosin II-C2: Time Resolved Confocal Microscopy. ChemistrySelect 2017. [DOI: 10.1002/slct.201601963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shyamtanu Chattoraj
- Department of Physical Chemistry; Indian Association for the Cultivation of Science; Jadavpur; Kolkata-32 INDIA
| | - Shekhar Saha
- Department of Biological Chemistry; Indian Association for the Cultivation of Science; Jadavpur; Kolkata-32 INDIA
- Department of Biochemistry and Molecular Genetics; University of Virginia; Charlottesville, VA USA
| | - Debdatta Halder
- Department of Biological Chemistry; Indian Association for the Cultivation of Science; Jadavpur; Kolkata-32 INDIA
| | - Siddhartha S. Jana
- Department of Biological Chemistry; Indian Association for the Cultivation of Science; Jadavpur; Kolkata-32 INDIA
| | - Kankan Bhattacharyya
- Department of Physical Chemistry; Indian Association for the Cultivation of Science; Jadavpur; Kolkata-32 INDIA
- Department of Chemistry; Indian Institute of Science Education and Research (IISER); Bhopal, Madhya Pradesh 462030 INDIA
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11
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Wei G, Xi W, Nussinov R, Ma B. Protein Ensembles: How Does Nature Harness Thermodynamic Fluctuations for Life? The Diverse Functional Roles of Conformational Ensembles in the Cell. Chem Rev 2016; 116:6516-51. [PMID: 26807783 PMCID: PMC6407618 DOI: 10.1021/acs.chemrev.5b00562] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
All soluble proteins populate conformational ensembles that together constitute the native state. Their fluctuations in water are intrinsic thermodynamic phenomena, and the distributions of the states on the energy landscape are determined by statistical thermodynamics; however, they are optimized to perform their biological functions. In this review we briefly describe advances in free energy landscape studies of protein conformational ensembles. Experimental (nuclear magnetic resonance, small-angle X-ray scattering, single-molecule spectroscopy, and cryo-electron microscopy) and computational (replica-exchange molecular dynamics, metadynamics, and Markov state models) approaches have made great progress in recent years. These address the challenging characterization of the highly flexible and heterogeneous protein ensembles. We focus on structural aspects of protein conformational distributions, from collective motions of single- and multi-domain proteins, intrinsically disordered proteins, to multiprotein complexes. Importantly, we highlight recent studies that illustrate functional adjustment of protein conformational ensembles in the crowded cellular environment. We center on the role of the ensemble in recognition of small- and macro-molecules (protein and RNA/DNA) and emphasize emerging concepts of protein dynamics in enzyme catalysis. Overall, protein ensembles link fundamental physicochemical principles and protein behavior and the cellular network and its regulation.
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Affiliation(s)
- Guanghong Wei
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Wenhui Xi
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University, Shanghai, P. R. China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
- Sackler Inst. of Molecular Medicine Department of Human Genetics and Molecular Medicine Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland 21702, USA
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12
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Quantifying the Assembly of Multicomponent Molecular Machines by Single-Molecule Total Internal Reflection Fluorescence Microscopy. Methods Enzymol 2016; 581:105-145. [PMID: 27793278 PMCID: PMC5403009 DOI: 10.1016/bs.mie.2016.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Large, dynamic macromolecular complexes play essential roles in many cellular processes. Knowing how the components of these complexes associate with one another and undergo structural rearrangements is critical to understanding how they function. Single-molecule total internal reflection fluorescence (TIRF) microscopy is a powerful approach for addressing these fundamental issues. In this article, we first discuss single-molecule TIRF microscopes and strategies to immobilize and fluorescently label macromolecules. We then review the use of single-molecule TIRF microscopy to study the formation of binary macromolecular complexes using one-color imaging and inhibitors. We conclude with a discussion of the use of TIRF microscopy to examine the formation of higher-order (i.e., ternary) complexes using multicolor setups. The focus throughout this article is on experimental design, controls, data acquisition, and data analysis. We hope that single-molecule TIRF microscopy, which has largely been the province of specialists, will soon become as common in the tool box of biophysicists and biochemists as structural approaches have become today.
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13
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Diensthuber RP, Tominaga M, Preller M, Hartmann FK, Orii H, Chizhov I, Oiwa K, Tsiavaliaris G. Kinetic mechanism of Nicotiana tabacum myosin-11 defines a new type of a processive motor. FASEB J 2015; 29:81-94. [PMID: 25326536 DOI: 10.1096/fj.14-254763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The 175-kDa myosin-11 from Nicotiana tabacum (Nt(175kDa)myosin-11) is exceptional in its mechanical activity as it is the fastest known processive actin-based motor, moving 10 times faster than the structurally related class 5 myosins. Although this ability might be essential for long-range organelle transport within larger plant cells, the kinetic features underlying the fast processive movement of Nt(175kDa)myosin-11 still remain unexplored. To address this, we generated a single-headed motor domain construct and carried out a detailed kinetic analysis. The data demonstrate that Nt(175kDa)myosin-11 is a high duty ratio motor, which remains associated with actin most of its enzymatic cycle. However, different from other processive myosins that establish a high duty ratio on the basis of a rate-limiting ADP-release step, Nt(175kDa)myosin-11 achieves a high duty ratio by a prolonged duration of the ATP-induced isomerization of the actin-bound states and ADP release kinetics, both of which in terms of the corresponding time constants approach the total ATPase cycle time. Molecular modeling predicts that variations in the charge distribution of the actin binding interface might contribute to the thermodynamic fine-tuning of the kinetics of this myosin. Our study unravels a new type of a high duty ratio motor and provides important insights into the molecular mechanism of processive movement of higher plant myosins.
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Affiliation(s)
- Ralph P Diensthuber
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Motoki Tominaga
- Live Cell Molecular Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama, Japan; Science and Technology Agency, PRESTO, Saitama, Japan
| | - Matthias Preller
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany; Centre for Structural Systems Biology, German Electron Synchrotron (DESY), Hamburg, Germany
| | - Falk K Hartmann
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Hidefumi Orii
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and
| | - Igor Chizhov
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Kazuhiro Oiwa
- Graduate School of Life Science, University of Hyogo, Hyogo, Japan; and Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe, Japan
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