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    The myosin interacting-heads motif present in live tarantula muscle explains tetanic and posttetanic phosphorylation mechanisms

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    Authors
    Padron, Raul
    Ma, Weikang
    Duno-Miranda, Sebastian
    Koubassova, Natalia
    Lee, Kyounghwan
    Pinto, Antonio
    Alamo, Lorenzo
    Bolanos, Pura
    Tsaturyan, Andrey
    Irving, Thomas
    Craig, Roger W.
    Show allShow less
    UMass Chan Affiliations
    Craig Lab
    Division of Cell Biology and Imaging, Department of Radiology
    Document Type
    Journal Article
    Publication Date
    2020-06-02
    Keywords
    myosin interacting-heads motif
    phosphorylation
    posttetanic potentiation
    skeletal muscle
    thick filament activation
    Amino Acids, Peptides, and Proteins
    Cellular and Molecular Physiology
    Enzymes and Coenzymes
    Musculoskeletal, Neural, and Ocular Physiology
    
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    Show full item record
    Link to Full Text
    https://doi.org/10.1073/pnas.1921312117
    Abstract
    Striated muscle contraction involves sliding of actin thin filaments along myosin thick filaments, controlled by calcium through thin filament activation. In relaxed muscle, the two heads of myosin interact with each other on the filament surface to form the interacting-heads motif (IHM). A key question is how both heads are released from the surface to approach actin and produce force. We used time-resolved synchrotron X-ray diffraction to study tarantula muscle before and after tetani. The patterns showed that the IHM is present in live relaxed muscle. Tetanic contraction produced only a very small backbone elongation, implying that mechanosensing-proposed in vertebrate muscle-is not of primary importance in tarantula. Rather, thick filament activation results from increases in myosin phosphorylation that release a fraction of heads to produce force, with the remainder staying in the ordered IHM configuration. After the tetanus, the released heads slowly recover toward the resting, helically ordered state. During this time the released heads remain close to actin and can quickly rebind, enhancing the force produced by posttetanic twitches, structurally explaining posttetanic potentiation. Taken together, these results suggest that, in addition to stretch activation in insects, two other mechanisms for thick filament activation have evolved to disrupt the interactions that establish the relaxed helices of IHMs: one in invertebrates, by either regulatory light-chain phosphorylation (as in arthropods) or Ca(2+)-binding (in mollusks, lacking phosphorylation), and another in vertebrates, by mechanosensing.
    Source

    Padrón R, Ma W, Duno-Miranda S, Koubassova N, Lee KH, Pinto A, Alamo L, Bolaños P, Tsaturyan A, Irving T, Craig R. The myosin interacting-heads motif present in live tarantula muscle explains tetanic and posttetanic phosphorylation mechanisms. Proc Natl Acad Sci U S A. 2020 Jun 2;117(22):11865-11874. doi: 10.1073/pnas.1921312117. Epub 2020 May 22. PMID: 32444484; PMCID: PMC7275770. Link to article on publisher's site

    DOI
    10.1073/pnas.1921312117
    Permanent Link to this Item
    http://hdl.handle.net/20.500.14038/48442
    PubMed ID
    32444484
    Related Resources

    Link to Article in PubMed

    Rights
    © 2020. PDF posted with 6-month embargo to author's website as allowed by publisher's default license at https://www.pnas.org/page/authors/licenses.
    ae974a485f413a2113503eed53cd6c53
    10.1073/pnas.1921312117
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    Radiology Publications
    Padrón-Craig Lab

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