Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle
Contraction of skeletal and cardiac muscle is controlled by Ca2+ ions via regulatory proteins, troponin (Tn) and tropomyosin (Tpm) associated with the thin actin filaments in sarcomeres. In the absence of Ca2+, Tn-C binds actin and shifts the Tpm strand to a position where it blocks myosin binding t...
| Main Authors: | , , , , |
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| Format: | Journal Article |
| Language: | English |
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2017
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| Online Access: | https://hdl.handle.net/10356/82598 http://hdl.handle.net/10220/42316 |
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| author | Koubassova, Natalia A. Bershitsky, Sergey Y. Ferenczi, Michael Alan Narayanan, Theyencheri Tsaturyan, Andrey K. |
| author2 | Lee Kong Chian School of Medicine (LKCMedicine) |
| author_facet | Lee Kong Chian School of Medicine (LKCMedicine) Koubassova, Natalia A. Bershitsky, Sergey Y. Ferenczi, Michael Alan Narayanan, Theyencheri Tsaturyan, Andrey K. |
| author_sort | Koubassova, Natalia A. |
| collection | NTU |
| description | Contraction of skeletal and cardiac muscle is controlled by Ca2+ ions via regulatory proteins, troponin (Tn) and tropomyosin (Tpm) associated with the thin actin filaments in sarcomeres. In the absence of Ca2+, Tn-C binds actin and shifts the Tpm strand to a position where it blocks myosin binding to actin, keeping muscle relaxed. According to the three-state model (McKillop and Geeves Biophys J 65:693–701, 1993), upon Ca2+ binding to Tn, Tpm rotates about the filament axis to a ‘closed state’ where some myosin heads can bind actin. Upon strong binding of myosin heads to actin, Tpm rotates further to an ‘open’ position where neighboring actin monomers also become available for myosin binding. Azimuthal Tpm movement in contracting muscle is detected by low-angle X-ray diffraction. Here we used high-resolution models of actin-Tpm filaments based on recent cryo-EM data for calculating changes in the intensities of X-ray diffraction reflections of muscle upon transitions between different states of the regulatory system. Calculated intensities of actin layer lines provide a much-improved fit to the experimental data obtained from rabbit muscle fibers in relaxed and rigor states than previous lower-resolution models. We show that the intensity of the second actin layer line at reciprocal radii from 0.15 to 0.3 nm−1 quantitatively reports the transition between different states of the regulatory system independently of the number of myosin heads bound to actin. |
| first_indexed | 2024-10-01T04:16:45Z |
| format | Journal Article |
| id | ntu-10356/82598 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T04:16:45Z |
| publishDate | 2017 |
| record_format | dspace |
| spelling | ntu-10356/825982020-11-01T05:16:59Z Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle Koubassova, Natalia A. Bershitsky, Sergey Y. Ferenczi, Michael Alan Narayanan, Theyencheri Tsaturyan, Andrey K. Lee Kong Chian School of Medicine (LKCMedicine) Actin Tropomyosin Contraction of skeletal and cardiac muscle is controlled by Ca2+ ions via regulatory proteins, troponin (Tn) and tropomyosin (Tpm) associated with the thin actin filaments in sarcomeres. In the absence of Ca2+, Tn-C binds actin and shifts the Tpm strand to a position where it blocks myosin binding to actin, keeping muscle relaxed. According to the three-state model (McKillop and Geeves Biophys J 65:693–701, 1993), upon Ca2+ binding to Tn, Tpm rotates about the filament axis to a ‘closed state’ where some myosin heads can bind actin. Upon strong binding of myosin heads to actin, Tpm rotates further to an ‘open’ position where neighboring actin monomers also become available for myosin binding. Azimuthal Tpm movement in contracting muscle is detected by low-angle X-ray diffraction. Here we used high-resolution models of actin-Tpm filaments based on recent cryo-EM data for calculating changes in the intensities of X-ray diffraction reflections of muscle upon transitions between different states of the regulatory system. Calculated intensities of actin layer lines provide a much-improved fit to the experimental data obtained from rabbit muscle fibers in relaxed and rigor states than previous lower-resolution models. We show that the intensity of the second actin layer line at reciprocal radii from 0.15 to 0.3 nm−1 quantitatively reports the transition between different states of the regulatory system independently of the number of myosin heads bound to actin. Accepted version 2017-05-03T06:49:11Z 2019-12-06T14:58:43Z 2017-05-03T06:49:11Z 2019-12-06T14:58:43Z 2016 Journal Article Koubassova, N. A., Bershitsky, S. Y., Ferenczi, M. A., Narayanan, T., & Tsaturyan, A. K. (2017). Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle. European Biophysics Journal, 46(4), 335-342. 0175-7571 https://hdl.handle.net/10356/82598 http://hdl.handle.net/10220/42316 10.1007/s00249-016-1174-6 en European Biophysics Journal © 2016 European Biophysical Societies' Association. This is the author created version of a work that has been peer reviewed and accepted for publication in European Biophysics Journal, published by Springer Berlin Heidelberg on behalf of European Biophysical Societies' Association. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1007/s00249-016-1174-6]. 19 p. application/pdf |
| spellingShingle | Actin Tropomyosin Koubassova, Natalia A. Bershitsky, Sergey Y. Ferenczi, Michael Alan Narayanan, Theyencheri Tsaturyan, Andrey K. Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title | Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title_full | Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title_fullStr | Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title_full_unstemmed | Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title_short | Tropomyosin movement is described by a quantitative high-resolution model of X-ray diffraction of contracting muscle |
| title_sort | tropomyosin movement is described by a quantitative high resolution model of x ray diffraction of contracting muscle |
| topic | Actin Tropomyosin |
| url | https://hdl.handle.net/10356/82598 http://hdl.handle.net/10220/42316 |
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