1
|
Schmidt AA, Grosberg AY, Grosberg A. A novel kinetic model to demonstrate the independent effects of ATP and ADP/Pi concentrations on sarcomere function. PLoS Comput Biol 2024; 20:e1012321. [PMID: 39102392 PMCID: PMC11326600 DOI: 10.1371/journal.pcbi.1012321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 08/15/2024] [Accepted: 07/12/2024] [Indexed: 08/07/2024] Open
Abstract
Understanding muscle contraction mechanisms is a standing challenge, and one of the approaches has been to create models of the sarcomere-the basic contractile unit of striated muscle. While these models have been successful in elucidating many aspects of muscle contraction, they fall short in explaining the energetics of functional phenomena, such as rigor, and in particular, their dependence on the concentrations of the biomolecules involved in the cross-bridge cycle. Our hypothesis posits that the stochastic time delay between ATP adsorption and ADP/Pi release in the cross-bridge cycle necessitates a modeling approach where the rates of these two reaction steps are controlled by two independent parts of the total free energy change of the hydrolysis reaction. To test this hypothesis, we built a two-filament, stochastic-mechanical half-sarcomere model that separates the energetic roles of ATP and ADP/Pi in the cross-bridge cycle's free energy landscape. Our results clearly demonstrate that there is a nontrivial dependence of the cross-bridge cycle's kinetics on the independent concentrations of ATP, ADP, and Pi. The simplicity of the proposed model allows for analytical solutions of the more basic systems, which provide novel insight into the dominant mechanisms driving some of the experimentally observed contractile phenomena.
Collapse
Affiliation(s)
- Andrew A Schmidt
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, United States of America
- UCI Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center (CIRC), University of California, Irvine, Irvine, California, United States of America
| | - Alexander Y Grosberg
- Department of Physics and Center for Soft Matter Research, New York University, New York, New York, United States of America
| | - Anna Grosberg
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California, United States of America
- UCI Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center (CIRC), University of California, Irvine, Irvine, California, United States of America
- Department of Chemical & Biomolecular Engineering, University of California, Irvine, Irvine, California, United States of America
- The NSF-Simons Center for Multiscale Cell Fate Research and Sue and Bill Gross Stem Cell Research Center and Center for Complex Biological Systems, University of California, Irvine, Irvine, California, United States of America
| |
Collapse
|
2
|
Bodt SML, Ge J, Ma W, Rasicci DV, Desetty R, McCammon JA, Yengo CM. Dilated cardiomyopathy mutation in beta-cardiac myosin enhances actin activation of the power stroke and phosphate release. PNAS NEXUS 2024; 3:pgae279. [PMID: 39108304 PMCID: PMC11302452 DOI: 10.1093/pnasnexus/pgae279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/25/2024] [Indexed: 08/13/2024]
Abstract
Inherited mutations in human beta-cardiac myosin (M2β) can lead to severe forms of heart failure. The E525K mutation in M2β is associated with dilated cardiomyopathy (DCM) and was found to stabilize the interacting heads motif (IHM) and autoinhibited super-relaxed (SRX) state in dimeric heavy meromyosin. However, in monomeric M2β subfragment 1 (S1) we found that E525K enhances (threefold) the maximum steady-state actin-activated ATPase activity (k cat) and decreases (eightfold) the actin concentration at which ATPase is one-half maximal (K ATPase). We also found a twofold to fourfold increase in the actin-activated power stroke and phosphate release rate constants at 30 μM actin, which overall enhanced the duty ratio threefold. Loaded motility assays revealed that the enhanced intrinsic motor activity translates to increased ensemble force in M2β S1. Glutamate 525, located near the actin binding region in the so-called activation loop, is highly conserved and predicted to form a salt bridge with another conserved residue (lysine 484) in the relay helix. Enhanced sampling molecular dynamics simulations predict that the charge reversal mutation disrupts the E525-K484 salt bridge, inducing conformations with a more flexible relay helix and a wide phosphate release tunnel. Our results highlight a highly conserved allosteric pathway associated with actin activation of the power stroke and phosphate release and suggest an important feature of the autoinhibited IHM is to prevent this region of myosin from interacting with actin. The ability of the E525K mutation to stabilize the IHM likely overrides the enhanced intrinsic motor properties, which may be key to triggering DCM pathogenesis.
Collapse
Affiliation(s)
- Skylar M L Bodt
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr, Hershey, PA 17033, USA
| | - Jinghua Ge
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr, Hershey, PA 17033, USA
| | - Wen Ma
- Department of Physics, University of Vermont, 149 Beaumont Avenue, Burlington, VT 05405, USA
| | - David V Rasicci
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr, Hershey, PA 17033, USA
- Department of Pathology, Anatomy, and Laboratory Medicine, West Virginia University School of Medicine, 64 Medical Center Dr, Morgantown, WV 26506, USA
| | - Rohini Desetty
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr, Hershey, PA 17033, USA
| | - J Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093, USA
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Dr, Hershey, PA 17033, USA
| |
Collapse
|
3
|
Hei B, Tardiff JC, Schwartz SD. Human cardiac β-myosin powerstroke energetics: Thin filament, Pi displacement, and mutation effects. Biophys J 2024:S0006-3495(24)00451-X. [PMID: 39001604 DOI: 10.1016/j.bpj.2024.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/01/2024] [Accepted: 07/09/2024] [Indexed: 07/25/2024] Open
Abstract
The powerstroke of human cardiac β-myosin is an important stage of the cross-bridge cycle that generates force for muscle contraction. However, the starting structure of this process has never been resolved, and the relative timing of the powerstroke and inorganic phosphate (Pi) release is still controversial. In this study, we generated an atomistic model of myosin on the thin filament and utilized metadynamics simulations to predict the absent starting structure of the powerstroke. We demonstrated that the displacement of Pi from the active site during the powerstroke is likely necessary, reducing the energy barrier of the conformation change. The effects of the presence of the thin filament, the hypertrophic cardiomyopathy mutation R712L, and the binding of mavacamten on the powerstroke process were also investigated.
Collapse
Affiliation(s)
- Bai Hei
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Jil C Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Steven D Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona.
| |
Collapse
|
4
|
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.
Collapse
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.)
| |
Collapse
|
5
|
Kelly CM, Martin JL, Previs MJ. Myosin folding boosts solubility in cardiac muscle sarcomeres. JCI Insight 2024; 9:e178131. [PMID: 38483507 PMCID: PMC11141871 DOI: 10.1172/jci.insight.178131] [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: 12/01/2023] [Accepted: 03/05/2024] [Indexed: 04/23/2024] Open
Abstract
The polymerization of myosin molecules into thick filaments in muscle sarcomeres is essential for cardiac contractility, with the attenuation of interactions between the heads of myosin molecules within the filaments being proposed to result in hypercontractility, as observed in hypertrophic cardiomyopathy (HCM). However, experimental evidence demonstrates that the structure of these giant macromolecular complexes is highly dynamic, with molecules exchanging between the filaments and a pool of soluble molecules on the minute timescale. Therefore, we sought to test the hypothesis that the enhancement of interactions between the heads of myosin molecules within thick filaments limits the mobility of myosin by taking advantage of mavacamten, a small molecule approved for the treatment of HCM. Myosin molecules were labeled in vivo with a green fluorescent protein (GFP) and imaged in intact hearts using multiphoton microscopy. Treatment of the intact hearts with mavacamten resulted in an unexpected > 5-fold enhancement in GFP-myosin mobility within the sarcomere. In vitro biochemical assays suggested that mavacamten enhanced the mobility of GFP-myosin by increasing the solubility of myosin molecules, through the stabilization of a compact/folded conformation of the molecules, once disassociated from the thick filaments. These findings provide alternative insight into the mechanisms by which molecules exchange into and out of thick filaments and have implications for how mavacamten may affect cardiac contractility.
Collapse
Affiliation(s)
- Colleen M Kelly
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Jody L Martin
- Department of Pharmacology, University of California, Davis, Davis, California, USA
| | - Michael J Previs
- Molecular Physiology and Biophysics Department, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| |
Collapse
|
6
|
Wong FL, Bunch TA, Lepak VC, Steedman AL, Colson BA. Cardiac myosin-binding protein C N-terminal interactions with myosin and actin filaments: Opposite effects of phosphorylation and M-domain mutations. J Mol Cell Cardiol 2024; 186:125-137. [PMID: 38008210 PMCID: PMC10872421 DOI: 10.1016/j.yjmcc.2023.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 10/26/2023] [Accepted: 11/17/2023] [Indexed: 11/28/2023]
Abstract
N-terminal cardiac myosin-binding protein C (cMyBP-C) domains (C0-C2) bind to thick (myosin) and thin (actin) filaments to coordinate contraction and relaxation of the heart. These interactions are regulated by phosphorylation of the M-domain situated between domains C1 and C2. In cardiomyopathies and heart failure, phosphorylation of cMyBP-C is significantly altered. We aimed to investigate how cMyBP-C interacts with myosin and actin. We developed complementary, high-throughput, C0-C2 FRET-based binding assays for myosin and actin to characterize the effects due to 5 HCM-linked variants or functional mutations in unphosphorylated and phosphorylated C0-C2. The assays indicated that phosphorylation decreases binding to both myosin and actin, whereas the HCM mutations in M-domain generally increase binding. The effects of mutations were greatest in phosphorylated C0-C2, and some mutations had a larger effect on actin than myosin binding. Phosphorylation also altered the spatial relationship of the probes on C0-C2 and actin. The magnitude of these structural changes was dependent on C0-C2 probe location (C0, C1, or M-domain). We conclude that binding can differ between myosin and actin due to phosphorylation or mutations. Additionally, these variables can change the mode of binding, affecting which of the interactions in cMyBP-C N-terminal domains with myosin or actin take place. The opposite effects of phosphorylation and M-domain mutations is consistent with the idea that cMyBP-C phosphorylation is critical for normal cardiac function. The precision of these assays is indicative of their usefulness in high-throughput screening of drug libraries for targeting cMyBP-C as therapy.
Collapse
Affiliation(s)
- Fiona L Wong
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Thomas A Bunch
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Victoria C Lepak
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Allison L Steedman
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States
| | - Brett A Colson
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ 85724, United States.
| |
Collapse
|
7
|
Scott B, Greenberg MJ. Multiscale biophysical models of cardiomyopathies reveal complexities challenging existing dogmas. Biophys J 2023; 122:4632-4634. [PMID: 38006882 PMCID: PMC10754685 DOI: 10.1016/j.bpj.2023.11.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/27/2023] Open
Abstract
Mutations in sarcomeric proteins, including myosin, cause a variety of cardiomyopathies. A prominent hypothesis has been that myosin mutations causing hypercontractility of the motor lead to hypertrophic cardiomyopathy, while those causing hypocontractility lead to dilated cardiomyopathy; however, recent biophysical studies using multiscale computational and experimental models have revealed complexities not captured by this hypothesis. We summarize recent publications in Biophysical Journal challenging this dogma and highlighting the need for multiscale modeling of these complex diseases.
Collapse
Affiliation(s)
- Brent Scott
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri.
| |
Collapse
|
8
|
Bodt SML, Ge J, Ma W, Rasicci DV, Desetty R, McCammon JA, Yengo CM. Dilated cardiomyopathy mutation in beta-cardiac myosin enhances actin activation of the power stroke and phosphate release. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.10.566646. [PMID: 38014187 PMCID: PMC10680644 DOI: 10.1101/2023.11.10.566646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Inherited mutations in human beta-cardiac myosin (M2β) can lead to severe forms of heart failure. The E525K mutation in M2β is associated with dilated cardiomyopathy (DCM) and was found to stabilize the interacting heads motif (IHM) and autoinhibited super-relaxed (SRX) state in dimeric heavy meromyosin. However, in monomeric M2β subfragment 1 (S1) we found that E525K enhances (3-fold) the maximum steady-state actin-activated ATPase activity (kcat) and decreases (6-fold) the actin concentration at which ATPase is one-half maximal (KATPase). We also found a 3 to 4-fold increase in the actin-activated power stroke and phosphate release rate constants at 30 μM actin, which overall enhanced the duty ratio 3-fold. Loaded motility assays revealed that the enhanced intrinsic motor activity translates to increased ensemble force in M2β S1. Glutamate 525, located near the actin binding region in the so-called activation loop, is highly conserved and predicted to form a salt-bridge with another conserved residue (lysine 484) in the relay helix. Enhanced sampling molecular dynamics simulations predict that the charge reversal mutation disrupts the E525-K484 salt-bridge, inducing conformations with a more flexible relay helix and a wide phosphate release tunnel. Our results highlight a highly conserved allosteric pathway associated with actin activation of the power stroke and phosphate release and suggest an important feature of the autoinhibited IHM is to prevent this region of myosin from interacting with actin. The ability of the E525K mutation to stabilize the IHM likely overrides the enhanced intrinsic motor properties, which may be key to triggering DCM pathogenesis.
Collapse
Affiliation(s)
- Skylar M. L. Bodt
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Jinghua Ge
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Wen Ma
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, California
| | - David V. Rasicci
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Rohini Desetty
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - J. Andrew McCammon
- Department of Chemistry and Biochemistry, University of California San Diego, San Diego, California
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| |
Collapse
|
9
|
Velayuthan LP, Moretto L, Tågerud S, Ušaj M, Månsson A. Virus-free transfection, transient expression, and purification of human cardiac myosin in mammalian muscle cells for biochemical and biophysical assays. Sci Rep 2023; 13:4101. [PMID: 36907906 PMCID: PMC10008826 DOI: 10.1038/s41598-023-30576-1] [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: 12/07/2022] [Accepted: 02/27/2023] [Indexed: 03/13/2023] Open
Abstract
Myosin expression and purification is important for mechanistic insights into normal function and mutation induced changes. The latter is particularly important for striated muscle myosin II where mutations cause several debilitating diseases. However, the heavy chain of this myosin is challenging to express and the standard protocol, using C2C12 cells, relies on viral infection. This is time and work intensive and associated with infrastructural demands and biological hazards, limiting widespread use and hampering fast generation of a wide range of mutations. We here develop a virus-free method to overcome these challenges. We use this system to transfect C2C12 cells with the motor domain of the human cardiac myosin heavy chain. After optimizing cell transfection, cultivation and harvesting conditions, we functionally characterized the expressed protein, co-purified with murine essential and regulatory light chains. The gliding velocity (1.5-1.7 µm/s; 25 °C) in the in vitro motility assay as well as maximum actin activated catalytic activity (kcat; 8-9 s-1) and actin concentration for half maximal activity (KATPase; 70-80 µM) were similar to those found previously using virus based infection. The results should allow new types of studies, e.g., screening of a wide range of mutations to be selected for further characterization.
Collapse
Affiliation(s)
- Lok Priya Velayuthan
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82, Kalmar, Sweden
| | - Luisa Moretto
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82, Kalmar, Sweden
| | - Sven Tågerud
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82, Kalmar, Sweden
| | - Marko Ušaj
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82, Kalmar, Sweden.
| | - Alf Månsson
- Department of Chemistry and Biomedical Sciences, Linnaeus University, 391 82, Kalmar, Sweden.
| |
Collapse
|
10
|
Doran MH, Rynkiewicz MJ, Pavadai E, Bodt SM, Rasicci D, Moore JR, Yengo CM, Bullitt E, Lehman W. Myosin loop-4 is critical for optimal tropomyosin repositioning on actin during muscle activation and relaxation. J Gen Physiol 2023; 155:e202213274. [PMID: 36459134 PMCID: PMC9723511 DOI: 10.1085/jgp.202213274] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 10/28/2022] [Accepted: 11/11/2022] [Indexed: 12/04/2022] Open
Abstract
During force-generating steps of the muscle crossbridge cycle, the tip of the myosin motor, specifically loop-4, contacts the tropomyosin cable of actin filaments. In the current study, we determined the corresponding effect of myosin loop-4 on the regulatory positioning of tropomyosin on actin. To accomplish this, we compared high-resolution cryo-EM structures of myosin S1-decorated thin filaments containing either wild-type or a loop-4 mutant construct, where the seven-residue portion of myosin loop-4 that contacts tropomyosin was replaced by glycine residues, thus removing polar side chains from residues 366-372. Cryo-EM analysis of fully decorated actin-tropomyosin filaments with wild-type and mutant S1, yielded 3.4-3.6 Å resolution reconstructions, with even higher definition at the actin-myosin interface. Loop-4 densities both in wild-type and mutant S1 were clearly identified, and side chains were resolved in the wild-type structure. Aside from loop-4, actin and myosin structural domains were indistinguishable from each other when filaments were decorated with either mutant or wild-type S1. In marked contrast, the position of tropomyosin on actin in the two reconstructions differed by 3 to 4 Å. In maps of filaments containing the mutant, tropomyosin was located closer to the myosin-head and thus moved in the direction of the C-state conformation adopted by myosin-free thin filaments. Complementary interaction energy measurements showed that tropomyosin in the mutant thin filaments sits on actin in a local energy minimum, whereas tropomyosin is positioned by wild-type S1 in an energetically unfavorable location. We propose that the high potential energy associated with tropomyosin positioning in wild-type filaments favors an effective transition to B- and C-states following release of myosin from the thin filaments during relaxation.
Collapse
Affiliation(s)
- Matthew H. Doran
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - Michael J. Rynkiewicz
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - Elumalai Pavadai
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - Skylar M.L. Bodt
- Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, PA
| | - David Rasicci
- Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, PA
| | - Jeffrey R. Moore
- Department of Biological Science, University of Massachusetts Lowell, Lowell, MA
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, PA
| | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| | - William Lehman
- Department of Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, Boston, MA
| |
Collapse
|
11
|
Doran MH, Rynkiewicz MJ, Rassici D, Bodt SM, Barry ME, Bullitt E, Yengo CM, Moore JR, Lehman W. Conformational changes linked to ADP release from human cardiac myosin bound to actin-tropomyosin. J Gen Physiol 2023; 155:213802. [PMID: 36633586 PMCID: PMC9859928 DOI: 10.1085/jgp.202213267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/11/2022] [Accepted: 12/14/2022] [Indexed: 01/13/2023] Open
Abstract
Following binding to the thin filament, β-cardiac myosin couples ATP-hydrolysis to conformational rearrangements in the myosin motor that drive myofilament sliding and cardiac ventricular contraction. However, key features of the cardiac-specific actin-myosin interaction remain uncertain, including the structural effect of ADP release from myosin, which is rate-limiting during force generation. In fact, ADP release slows under experimental load or in the intact heart due to the afterload, thereby adjusting cardiac muscle power output to meet physiological demands. To further elucidate the structural basis of this fundamental process, we used a combination of cryo-EM reconstruction methodologies to determine structures of the human cardiac actin-myosin-tropomyosin filament complex at better than 3.4 Å-resolution in the presence and in the absence of Mg2+·ADP. Focused refinements of the myosin motor head and its essential light chains in these reconstructions reveal that small changes in the nucleotide-binding site are coupled to significant rigid body movements of the myosin converter domain and a 16-degree lever arm swing. Our structures provide a mechanistic framework to understand the effect of ADP binding and release on human cardiac β-myosin, and offer insights into the force-sensing mechanism displayed by the cardiac myosin motor.
Collapse
Affiliation(s)
- Matthew H. Doran
- School of Medicine, Department of Physiology and Biophysics, Boston University, Boston, MA, USA,Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Michael J. Rynkiewicz
- School of Medicine, Department of Physiology and Biophysics, Boston University, Boston, MA, USA
| | - David Rassici
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Skylar M.L. Bodt
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Meaghan E. Barry
- Department of Biological Science, University of Massachusetts Lowell, Lowell, MA, USA
| | - Esther Bullitt
- School of Medicine, Department of Physiology and Biophysics, Boston University, Boston, MA, USA
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, PA, USA
| | - Jeffrey R. Moore
- Department of Biological Science, University of Massachusetts Lowell, Lowell, MA, USA
| | - William Lehman
- School of Medicine, Department of Physiology and Biophysics, Boston University, Boston, MA, USA
| |
Collapse
|
12
|
Chakraborti A, Tardiff JC, Schwartz SD. Insights into the Mechanism of the Cardiac Drug Omecamtiv Mecarbil─A Computational Study. J Phys Chem B 2022; 126:10069-10082. [PMID: 36448224 PMCID: PMC9830884 DOI: 10.1021/acs.jpcb.2c06679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Omecamtiv mecarbil (OM) is a positive inotrope that is thought to bind directly to an allosteric site of the β-cardiac myosin. The drug is under investigation for the treatment of systolic heart failure. The drug is classified as a cardiac myosin modulator and has been observed to affect multiple vital steps of the cross-bridge cycle including the recovery stroke and the chemical step. We explored the free-energy surface of the recovery stroke of the human cardiac β-myosin in the presence of OM to determine its influence on this process. We also investigated the effects of OM on the recovery stroke in the presence of genetic cardiomyopathic mutations R712L, F764L, and P710R using metadynamics. We also utilized the method of transition path sampling to generate an unbiased ensemble of reactive trajectories for the ATP hydrolysis step in the presence of OM that were able to provide insight into the differences observed due to OM in the dynamics and mechanism of the decomposition of ATP to ADP and HPO42-, a central part of the power generation in cardiac muscle. We studied chemistry in the presence of the same three mutations to further elucidate the effect of OM, and its use in the treatment of cardiac disease.
Collapse
Affiliation(s)
- Ananya Chakraborti
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Jil C. Tardiff
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona 85724, United States
| | - Steven D. Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| |
Collapse
|
13
|
Rasicci DV, Tiwari P, Bodt SML, Desetty R, Sadler FR, Sivaramakrishnan S, Craig R, Yengo CM. Dilated cardiomyopathy mutation E525K in human beta-cardiac myosin stabilizes the interacting-heads motif and super-relaxed state of myosin. eLife 2022; 11:e77415. [PMID: 36422472 PMCID: PMC9691020 DOI: 10.7554/elife.77415] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 11/08/2022] [Indexed: 11/25/2022] Open
Abstract
The auto-inhibited, super-relaxed (SRX) state of cardiac myosin is thought to be crucial for regulating contraction, relaxation, and energy conservation in the heart. We used single ATP turnover experiments to demonstrate that a dilated cardiomyopathy (DCM) mutation (E525K) in human beta-cardiac myosin increases the fraction of myosin heads in the SRX state (with slow ATP turnover), especially in physiological ionic strength conditions. We also utilized FRET between a C-terminal GFP tag on the myosin tail and Cy3ATP bound to the active site of the motor domain to estimate the fraction of heads in the closed, interacting-heads motif (IHM); we found a strong correlation between the IHM and SRX state. Negative stain electron microscopy and 2D class averaging of the construct demonstrated that the E525K mutation increased the fraction of molecules adopting the IHM. Overall, our results demonstrate that the E525K DCM mutation may reduce muscle force and power by stabilizing the auto-inhibited SRX state. Our studies also provide direct evidence for a correlation between the SRX biochemical state and the IHM structural state in cardiac muscle myosin. Furthermore, the E525 residue may be implicated in crucial electrostatic interactions that modulate this conserved, auto-inhibited conformation of myosin.
Collapse
Affiliation(s)
- David V Rasicci
- Department of Cellular and Molecular Physiology, Penn State College of MedicineHersheyUnited States
| | - Prince Tiwari
- Department of Radiology, Division of Cell Biology and Imaging, UMass Chan Medical SchoolWorcesterUnited States
| | - Skylar ML Bodt
- Department of Cellular and Molecular Physiology, Penn State College of MedicineHersheyUnited States
| | - Rohini Desetty
- Department of Cellular and Molecular Physiology, Penn State College of MedicineHersheyUnited States
| | - Fredrik R Sadler
- Department of Genetics, Cell Biology, and Development, University of Minnesota Twin CitiesMinneapolisUnited States
| | - Sivaraj Sivaramakrishnan
- Department of Genetics, Cell Biology, and Development, University of Minnesota Twin CitiesMinneapolisUnited States
| | - Roger Craig
- Department of Radiology, Division of Cell Biology and Imaging, UMass Chan Medical SchoolWorcesterUnited States
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, Penn State College of MedicineHersheyUnited States
| |
Collapse
|
14
|
Liu PJ, Gunther LK, Garone ME, Zhang C, Perez D, Bi-Karchin J, Pellenz CD, Chase SE, Presti MF, Plante EL, Martin CE, Lovric S, Yengo CM, Hildebrandt F, Krendel M. Steroid-Resistant Nephrotic Syndrome-Associated MYO1E Mutations Have Differential Effects on Myosin 1e Localization, Dynamics, and Activity. J Am Soc Nephrol 2022; 33:1989-2007. [PMID: 36316095 PMCID: PMC9678034 DOI: 10.1681/asn.2021111505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 08/22/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Myo1e is a nonmuscle motor protein enriched in podocytes. Mutations in MYO1E are associated with steroid-resistant nephrotic syndrome (SRNS). Most of the MYO1E variants identified by genomic sequencing have not been functionally characterized. Here, we set out to analyze two mutations in the Myo1e motor domain, T119I and D388H, which were selected on the basis of protein sequence conservation. METHODS EGFP-tagged human Myo1e constructs were delivered into the Myo1e-KO mouse podocyte-derived cells via adenoviral infection to analyze Myo1e protein stability, Myo1e localization, and clathrin-dependent endocytosis, which is known to involve Myo1e activity. Furthermore, truncated Myo1e constructs were expressed using the baculovirus expression system and used to measure Myo1e ATPase and motor activity in vitro. RESULTS Both mutants were expressed as full-length proteins in the Myo1e-KO cells. However, unlike wild-type (WT) Myo1e, the T119I variant was not enriched at the cell junctions or clathrin-coated vesicles (CCVs). In contrast, D388H variant localization was similar to that of WT. The rate of dissociation of the D388H variant from cell-cell junctions and CCVs was decreased, suggesting this mutation affects Myo1e interactions with binding partners. ATPase activity and ability to translocate actin filaments were drastically reduced for the D388H mutant, supporting findings from cell-based experiments. CONCLUSIONS T119I and D388H mutations are deleterious to Myo1e functions. The experimental approaches used in this study can be applied to future characterization of novel MYO1E variants associated with SRNS.
Collapse
Affiliation(s)
- Pei-Ju Liu
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Laura K. Gunther
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Michael E. Garone
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Chunling Zhang
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York
| | - Diana Perez
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Jing Bi-Karchin
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Christopher D. Pellenz
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Sharon E. Chase
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Maria F. Presti
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Eric L. Plante
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Claire E. Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
| | - Svjetlana Lovric
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Friedhelm Hildebrandt
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| |
Collapse
|
15
|
Debold EP. Mini‐ review: Recent insights into the relative timing of myosin’s powerstroke and release of phosphate. Cytoskeleton (Hoboken) 2022; 78:448-458. [DOI: 10.1002/cm.21695] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/25/2022] [Accepted: 03/08/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Edward P. Debold
- Department of Kinesiology University of Massachusetts Amherst Massachusetts
| |
Collapse
|
16
|
Barrick SK, Greenberg MJ. Cardiac myosin contraction and mechanotransduction in health and disease. J Biol Chem 2021; 297:101297. [PMID: 34634306 PMCID: PMC8559575 DOI: 10.1016/j.jbc.2021.101297] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 12/17/2022] Open
Abstract
Cardiac myosin is the molecular motor that powers heart contraction by converting chemical energy from ATP hydrolysis into mechanical force. The power output of the heart is tightly regulated to meet the physiological needs of the body. Recent multiscale studies spanning from molecules to tissues have revealed complex regulatory mechanisms that fine-tune cardiac contraction, in which myosin not only generates power output but also plays an active role in its regulation. Thus, myosin is both shaped by and actively involved in shaping its mechanical environment. Moreover, these studies have shown that cardiac myosin-generated tension affects physiological processes beyond muscle contraction. Here, we review these novel regulatory mechanisms, as well as the roles that myosin-based force generation and mechanotransduction play in development and disease. We describe how key intra- and intermolecular interactions contribute to the regulation of myosin-based contractility and the role of mechanical forces in tuning myosin function. We also discuss the emergence of cardiac myosin as a drug target for diseases including heart failure, leading to the discovery of therapeutics that directly tune myosin contractility. Finally, we highlight some of the outstanding questions that must be addressed to better understand myosin's functions and regulation, and we discuss prospects for translating these discoveries into precision medicine therapeutics targeting contractility and mechanotransduction.
Collapse
Affiliation(s)
- Samantha K Barrick
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael J Greenberg
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, USA.
| |
Collapse
|