Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments
Regulated thin filaments (RTFs) tightly control striated muscle contraction through calcium binding to troponin, which enables tropomyosin to expose myosin-binding sites on actin. Myosin binding holds tropomyosin in an open position, exposing more myosin-binding sites on actin, leading to cooperativ...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2021-09-01
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| Series: | eLife |
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| Online Access: | https://elifesciences.org/articles/69184 |
| _version_ | 1811227746672574464 |
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| author | Quentin M Smith Alessio V Inchingolo Madalina-Daniela Mihailescu Hongsheng Dai Neil M Kad |
| author_facet | Quentin M Smith Alessio V Inchingolo Madalina-Daniela Mihailescu Hongsheng Dai Neil M Kad |
| author_sort | Quentin M Smith |
| collection | DOAJ |
| description | Regulated thin filaments (RTFs) tightly control striated muscle contraction through calcium binding to troponin, which enables tropomyosin to expose myosin-binding sites on actin. Myosin binding holds tropomyosin in an open position, exposing more myosin-binding sites on actin, leading to cooperative activation. At lower calcium levels, troponin and tropomyosin turn off the thin filament; however, this is antagonised by the high local concentration of myosin, questioning how the thin filament relaxes. To provide molecular details of deactivation, we used single-molecule imaging of green fluorescent protein (GFP)-tagged myosin-S1 (S1-GFP) to follow the activation of RTF tightropes. In sub-maximal activation conditions, RTFs are not fully active, enabling direct observation of deactivation in real time. We observed that myosin binding occurs in a stochastic step-wise fashion; however, an unexpectedly large probability of multiple contemporaneous detachments is observed. This suggests that deactivation of the thin filament is a coordinated active process. |
| first_indexed | 2024-04-12T09:46:52Z |
| format | Article |
| id | doaj.art-b292140cde184a14b4f0e4ce71ad097e |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-12T09:46:52Z |
| publishDate | 2021-09-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-b292140cde184a14b4f0e4ce71ad097e2022-12-22T03:37:56ZengeLife Sciences Publications LtdeLife2050-084X2021-09-011010.7554/eLife.69184Single-molecule imaging reveals the concerted release of myosin from regulated thin filamentsQuentin M Smith0https://orcid.org/0000-0003-2967-9240Alessio V Inchingolo1Madalina-Daniela Mihailescu2Hongsheng Dai3Neil M Kad4https://orcid.org/0000-0002-3491-8595School of Biosciences, University of Kent, Canterbury, United KingdomSchool of Biosciences, University of Kent, Canterbury, United KingdomDepartment of Mathematical Sciences, University of Essex, Colchester, United KingdomDepartment of Mathematical Sciences, University of Essex, Colchester, United KingdomSchool of Biosciences, University of Kent, Canterbury, United KingdomRegulated thin filaments (RTFs) tightly control striated muscle contraction through calcium binding to troponin, which enables tropomyosin to expose myosin-binding sites on actin. Myosin binding holds tropomyosin in an open position, exposing more myosin-binding sites on actin, leading to cooperative activation. At lower calcium levels, troponin and tropomyosin turn off the thin filament; however, this is antagonised by the high local concentration of myosin, questioning how the thin filament relaxes. To provide molecular details of deactivation, we used single-molecule imaging of green fluorescent protein (GFP)-tagged myosin-S1 (S1-GFP) to follow the activation of RTF tightropes. In sub-maximal activation conditions, RTFs are not fully active, enabling direct observation of deactivation in real time. We observed that myosin binding occurs in a stochastic step-wise fashion; however, an unexpectedly large probability of multiple contemporaneous detachments is observed. This suggests that deactivation of the thin filament is a coordinated active process.https://elifesciences.org/articles/69184cooperativitymuscleactinfluorescence imagingregulationcalcium |
| spellingShingle | Quentin M Smith Alessio V Inchingolo Madalina-Daniela Mihailescu Hongsheng Dai Neil M Kad Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments eLife cooperativity muscle actin fluorescence imaging regulation calcium |
| title | Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| title_full | Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| title_fullStr | Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| title_full_unstemmed | Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| title_short | Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| title_sort | single molecule imaging reveals the concerted release of myosin from regulated thin filaments |
| topic | cooperativity muscle actin fluorescence imaging regulation calcium |
| url | https://elifesciences.org/articles/69184 |
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