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Variants of the myosin interacting-heads motif

Under relaxing conditions, the two heads of myosin II interact with each other and with the proximal part (S2) of the myosin tail, establishing the interacting-heads motif (IHM), found in myosin molecules and thick filaments of muscle and nonmuscle cells. The IHM is normally thought of as a single,...

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Autores principales: Padrón, Raúl, Dutta, Debabrata, Craig, Roger
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Rockefeller University Press 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9648617/
https://www.ncbi.nlm.nih.gov/pubmed/36346431
http://dx.doi.org/10.1085/jgp.202213249
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author Padrón, Raúl
Dutta, Debabrata
Craig, Roger
author_facet Padrón, Raúl
Dutta, Debabrata
Craig, Roger
author_sort Padrón, Raúl
collection PubMed
description Under relaxing conditions, the two heads of myosin II interact with each other and with the proximal part (S2) of the myosin tail, establishing the interacting-heads motif (IHM), found in myosin molecules and thick filaments of muscle and nonmuscle cells. The IHM is normally thought of as a single, unique structure, but there are several variants. In the simplest (“canonical”) IHM, occurring in most relaxed thick filaments and in heavy meromyosin, the interacting heads bend back and interact with S2, and the motif lies parallel to the filament surface. In one variant, occurring in insect indirect flight muscle, there is no S2–head interaction and the motif is perpendicular to the filament. In a second variant, found in smooth and nonmuscle single myosin molecules in their inhibited (10S) conformation, S2 is shifted ∼20 Å from the canonical form and the tail folds twice and wraps around the interacting heads. These molecule and filament IHM variants have important energetic and pathophysiological consequences. (1) The canonical motif, with S2–head interaction, correlates with the super-relaxed (SRX) state of myosin. The absence of S2–head interaction in insects may account for the lower stability of this IHM and apparent absence of SRX in indirect flight muscle, contributing to the quick initiation of flight in insects. (2) The ∼20 Å shift of S2 in 10S myosin molecules means that S2–head interactions are different from those in the canonical IHM. This variant therefore cannot be used to analyze the impact of myosin mutations on S2–head interactions that occur in filaments, as has been proposed. It can be used, instead, to analyze the structural impact of mutations in smooth and nonmuscle myosin.
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spelling pubmed-96486172023-05-08 Variants of the myosin interacting-heads motif Padrón, Raúl Dutta, Debabrata Craig, Roger J Gen Physiol Commentary Under relaxing conditions, the two heads of myosin II interact with each other and with the proximal part (S2) of the myosin tail, establishing the interacting-heads motif (IHM), found in myosin molecules and thick filaments of muscle and nonmuscle cells. The IHM is normally thought of as a single, unique structure, but there are several variants. In the simplest (“canonical”) IHM, occurring in most relaxed thick filaments and in heavy meromyosin, the interacting heads bend back and interact with S2, and the motif lies parallel to the filament surface. In one variant, occurring in insect indirect flight muscle, there is no S2–head interaction and the motif is perpendicular to the filament. In a second variant, found in smooth and nonmuscle single myosin molecules in their inhibited (10S) conformation, S2 is shifted ∼20 Å from the canonical form and the tail folds twice and wraps around the interacting heads. These molecule and filament IHM variants have important energetic and pathophysiological consequences. (1) The canonical motif, with S2–head interaction, correlates with the super-relaxed (SRX) state of myosin. The absence of S2–head interaction in insects may account for the lower stability of this IHM and apparent absence of SRX in indirect flight muscle, contributing to the quick initiation of flight in insects. (2) The ∼20 Å shift of S2 in 10S myosin molecules means that S2–head interactions are different from those in the canonical IHM. This variant therefore cannot be used to analyze the impact of myosin mutations on S2–head interactions that occur in filaments, as has been proposed. It can be used, instead, to analyze the structural impact of mutations in smooth and nonmuscle myosin. Rockefeller University Press 2022-11-08 /pmc/articles/PMC9648617/ /pubmed/36346431 http://dx.doi.org/10.1085/jgp.202213249 Text en © 2022 Padron et al. https://creativecommons.org/licenses/by-nc-sa/4.0/http://www.rupress.org/terms/This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Commentary
Padrón, Raúl
Dutta, Debabrata
Craig, Roger
Variants of the myosin interacting-heads motif
title Variants of the myosin interacting-heads motif
title_full Variants of the myosin interacting-heads motif
title_fullStr Variants of the myosin interacting-heads motif
title_full_unstemmed Variants of the myosin interacting-heads motif
title_short Variants of the myosin interacting-heads motif
title_sort variants of the myosin interacting-heads motif
topic Commentary
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9648617/
https://www.ncbi.nlm.nih.gov/pubmed/36346431
http://dx.doi.org/10.1085/jgp.202213249
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