Myosin II sequences for Lethocerus indicus

Fee, Lanette; Lin, Weili; Qiu, Feng; Edwards, Robert J.

doi:10.1007/s10974-017-9476-6

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…This also correlates with the increased ATPase rate for the IFM isoform (40). We conclude that the IHM is present in both isoforms of insect myosin II but is less stable in the flight muscle, presumably as a result of differences in critical regions of the protein that are encoded by alternative exons (40,103). This is consistent with the lower level of charge attraction predicted (on the basis of sequence comparison) in the IHM interfaces of IFM compared with EMB myosin (70,103).…”

Section: Discussionsupporting

confidence: 79%

Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals

Lee

Sulbarán

Yang

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

111

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Electron microscope studies have shown that the switched-off state of myosin II in muscle involves intramolecular interaction between the two heads of myosin and between one head and the tail. The interaction, seen in both myosin filaments and isolated molecules, inhibits activity by blocking actin-binding and ATPase sites on myosin. This interacting-heads motif is highly conserved, occurring in invertebrates and vertebrates, in striated, smooth, and nonmuscle myosin IIs, and in myosins regulated by both Ca binding and regulatory light-chain phosphorylation. Our goal was to determine how early this motif arose by studying the structure of inhibited myosin II molecules from primitive animals and from earlier, unicellular species that predate animals. Myosin II from (sea anemones, jellyfish), the most primitive animals with muscles, and (sponges), the most primitive of all animals (lacking muscle tissue) showed the same interacting-heads structure as myosins from higher animals, confirming the early origin of the motif. The social amoeba showed a similar, but modified, version of the motif, while the amoeba and fission yeast () showed no head-head interaction, consistent with the different sequences and regulatory mechanisms of these myosins compared with animal myosin IIs. Our results suggest that head-head/head-tail interactions have been conserved, with slight modifications, as a mechanism for regulating myosin II activity from the emergence of the first animals and before. The early origins of these interactions highlight their importance in generating the inhibited (relaxed) state of myosin in muscle and nonmuscle cells.

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Section: Discussionsupporting

confidence: 79%

Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals

Lee

Sulbarán

Yang

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

111

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“…This is probably a consequence of the intrinsic flexibility of the IHM paired heads arrangement (Yang et al 2015a) especially of the free swaying heads as explained below (Brito et al 2011;Sulbarán et al 2013). Interestingly, it has been recently reported that a lack of negative charge in S2 may explain why Lethocerus thick filaments display an IHM perpendicular to the filament axis, rather than a parallel one as seen in tarantula (Fee et al 2017). In retrospect, both head densities resolved in frozenhydrated 3D reconstructions (Fig.…”

Section: Solving the Ihm Near Atomic And The Hmm Atomic Structuresmentioning

confidence: 79%

Lessons from a tarantula: new insights into muscle thick filament and myosin interacting-heads motif structure and function

et al. 2017

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The tarantula skeletal muscle X-ray diffraction pattern suggested that the myosin heads were helically arranged on the thick filaments. Electron microscopy (EM) of negatively stained relaxed tarantula thick filaments revealed four helices of heads allowing a helical 3D reconstruction. Due to its low resolution (5.0 nm), the unambiguous interpretation of densities of both heads was not possible. A resolution increase up to 2.5 nm, achieved by cryo-EM of frozen-hydrated relaxed thick filaments and an iterative helical real space reconstruction, allowed the resolving of both heads. The two heads, Bfree^and Bblocked^, formed an asymmetric structure named the Binteracting-heads motif^(IHM) which explained relaxation by self-inhibition of both heads ATPases. This finding made tarantula an exemplar system for thick filament structure and function studies. Heads were shown to be released and disordered by Ca 2+ -activation through myosin regulatory light chain phosphorylation, leading to EM, small angle X-ray diffraction and scattering, and spectroscopic and biochemical studies of the IHM structure and function. The results from these studies have consequent implications for understanding and explaining myosin super-relaxed state and thick filament activation and regulation. A cooperative phosphorylation mechanism for activation in tarantula skeletal muscle, involving swaying constitutively Ser35 mono-phosphorylated free heads, explains super-relaxation, force potentiation and posttetanic potentiation through Ser45 mono-phosphorylated blocked heads. Based on this mechanism, we propose a swaying-swinging, tilting crossbridge-sliding filament for tarantula muscle contraction.

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“…1D), which does not fold back to contact its own S2 (Hu et al, 2016); and thus the S2-blocked head contact must not be strictly required to form a stable IHM. Moreover, the Lethocerus flight muscle myosin sequence lacks the net negative charge (Fee et al, 2017), which is thought to stabilize the folded-back S2-blocked head contact (Alamo et al, 2016; Blankenfeldt et al, 2006). We conclude that while the blocked head-S2 interaction provides stability in some myosin species, it is not essential to formation of the IHM in all cases.…”

Section: Discussionmentioning

confidence: 99%

Coupling between myosin head conformation and the thick filament backbone structure

Taylor

Edwards

et al. 2017

Journal of Structural Biology

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The recent high-resolution structure of the thick filament from Lethocerus asynchronous flight muscle shows aspects of thick filament structure never before revealed that may shed some light on how striated muscles function. The phenomenon of stretch activation underlies the function of asynchronous flight muscle. It is most highly developed in flight muscle, but is also observed in other striated muscles such as cardiac muscle. Although stretch activation is likely to be complex, involving more than a single structural aspect of striated muscle, the thick filament itself, would be a prime site for regulatory function because it must bear all of the tension produced by both its associated myosin motors and any externally applied force. Here we show the first structural evidence that the arrangement of myosin heads within the interacting heads motif is coupled to the structure of the thick filament backbone. We find that a change in helical angle of 0.16° disorders the blocked head preferentially within the Lethocerus interacting heads motif. This observation suggests a mechanism for how tension affects the dynamics of the myosin heads leading to a detailed hypothesis for stretch activation and shortening deactivation, in which the blocked head preferentially binds the thin filament followed by the free head when force production occurs.

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Myosin II sequences for Lethocerus indicus

Cited by 6 publications

References 36 publications

Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals

Interacting-heads motif has been conserved as a mechanism of myosin II inhibition since before the origin of animals

Lessons from a tarantula: new insights into muscle thick filament and myosin interacting-heads motif structure and function

Coupling between myosin head conformation and the thick filament backbone structure

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