title: In vivo myosin step-size from zebrafish skeletal muscle.
abstract: Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the 'bottom-up' myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation. Macroscopic muscle physiological experimentation provides the definitive 'top-down' phenotype characterizations that are the concerns in translational medicine. In vivo single myosin detection in muscle from zebrafish embryo models for human muscle fulfils ambitions for both bottom-up and top-down experimentation. A photoactivatable green fluorescent protein (GFP)-tagged myosin light chain expressed in transgenic zebrafish skeletal muscle specifically modifies the myosin lever-arm. Strychnine induces the simultaneous contraction of the bilateral tail muscles in a live embryo, causing them to be isometric while active. Highly inclined thin illumination excites the GFP tag of single lever-arms and its super-resolution orientation is measured from an active isometric muscle over a time sequence covering many transduction cycles. Consecutive frame lever-arm angular displacement converts to step-size by its product with the estimated lever-arm length. About 17% of the active myosin steps that fall between 2 and 7 nm are implicated as powerstrokes because they are beyond displacements detected from either relaxed or ATP-depleted (rigor) muscle.
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA Department of Physiology and Biomedical Engineering, Mayo Clinic Rochester, Rochester, MN 55905, USA burghardt@mayo.edu.
authors.forename: Thomas P
authors.identifier: 0000-0003-3119-4074
authors.initials: TP
authors.lastname: Burghardt
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA.
authors.forename: Katalin
authors.initials: K
authors.lastname: Ajtai
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA.
authors.forename: Naoko
authors.initials: N
authors.lastname: Takubo
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic Rochester, Rochester, MN 55905, USA.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D018482:Muscle, Skeletal / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D018994:Myosin Light Chains / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013331:Strychnine / Q000494:pharmacology; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
chemical_list: D000199:Actins; D018994:Myosin Light Chains; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D013331:Strychnine
keywords: highly inclined thin illumination; single myosin detection in vivo; strychnine induced contraction; transgenic zebrafish skeletal muscle; zebrafish skeletal myosin powerstroke; zebrafish skeletal myosin step-size