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...

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Autores principales:	Quentin M Smith, Alessio V Inchingolo, Madalina-Daniela Mihailescu, Hongsheng Dai, Neil M Kad
Formato:	article
Lenguaje:	EN
Publicado:	eLife Sciences Publications Ltd 2021
Materias:	cooperativity muscle actin fluorescence imaging regulation calcium Medicine R Science Q Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/b292140cde184a14b4f0e4ce71ad097e
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spelling	oai:doaj.org-article:b292140cde184a14b4f0e4ce71ad097e2021-11-26T11:12:14ZSingle-molecule imaging reveals the concerted release of myosin from regulated thin filaments10.7554/eLife.691842050-084Xe69184https://doaj.org/article/b292140cde184a14b4f0e4ce71ad097e2021-09-01T00:00:00Zhttps://elifesciences.org/articles/69184https://doaj.org/toc/2050-084XRegulated 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.Quentin M SmithAlessio V InchingoloMadalina-Daniela MihailescuHongsheng DaiNeil M KadeLife Sciences Publications Ltdarticlecooperativitymuscleactinfluorescence imagingregulationcalciumMedicineRScienceQBiology (General)QH301-705.5ENeLife, Vol 10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	cooperativity muscle actin fluorescence imaging regulation calcium Medicine R Science Q Biology (General) QH301-705.5
spellingShingle	cooperativity muscle actin fluorescence imaging regulation calcium Medicine R Science Q Biology (General) QH301-705.5 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
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.
format	article
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
title	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_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_sort	single-molecule imaging reveals the concerted release of myosin from regulated thin filaments
publisher	eLife Sciences Publications Ltd
publishDate	2021
url	https://doaj.org/article/b292140cde184a14b4f0e4ce71ad097e
work_keys_str_mv	AT quentinmsmith singlemoleculeimagingrevealstheconcertedreleaseofmyosinfromregulatedthinfilaments AT alessiovinchingolo singlemoleculeimagingrevealstheconcertedreleaseofmyosinfromregulatedthinfilaments AT madalinadanielamihailescu singlemoleculeimagingrevealstheconcertedreleaseofmyosinfromregulatedthinfilaments AT hongshengdai singlemoleculeimagingrevealstheconcertedreleaseofmyosinfromregulatedthinfilaments AT neilmkad singlemoleculeimagingrevealstheconcertedreleaseofmyosinfromregulatedthinfilaments
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Single-molecule imaging reveals the concerted release of myosin from regulated thin filaments

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