The use of negative staining and cryo-electron microscopy to understand the molecular mechanism of myosin-linked regulation of striated muscle contraction
Título del documento: The use of negative staining and cryo-electron microscopy to understand the molecular mechanism of myosin-linked regulation of striated muscle contraction
Revista: Acta microscópica
Base de datos: PERIÓDICA
Número de sistema: 000269183
ISSN: 0798-4545
Autores: 1
Instituciones: 1Instituto Venezolano de Investigaciones Científicas, Departamento de Biología Estructural, Caracas, Distrito Federal. Venezuela
Año:
Volumen: 13
Número: 1-2
Paginación: 14-29
País: Venezuela
Idioma: Inglés
Tipo de documento: Artículo
Enfoque: Descriptivo
Resumen en español Este modelo atómico ha abierto el camino para la dilucidación del mecanismo molecular de la regulación ligada a miosina de la contracción de músculo estriado
Resumen en inglés The sliding of thick filaments along thin filaments is produced by the active shortening of the striated muscle during contraction, and is controlled by molecular switches in the thin and/or thick filaments. In spite of advances on the elucidation of the molecular mechanism of actin-linked regulation, the myosin-linked regulation mechanism has been less amenable to structural studies, due to the low resolution of the threedimensional (3D) reconstruction maps. A combination of adequate specimens, an improved negative staining method that preserve myosin heads helices and the use of improved reconstruction techniques, allowed the calculation of a 5 nm resolution 3D-map. This 3D-map was interpreted with the available myosin head structural information, but the fitting of atomic structures remained ambiguous due to the limited resolution. Cryo-electron microscopy (EM) of frozen-hydrated tarantula thick filaments extended resolution to 2.5 nm, and the use of single particle averaging techniques enabled the calculation of a 2.5 nm 3D-map. This 3D-map was interpreted unambiguously by fitting the heavy meromyosin atomic structure to it, leading to the atomic model of the relaxed thick filament, which revealed intraand intermolecular interactions that keep myosin heads forming helices closer to the backbone surface. EM and X-ray evidences suggested that phosphorylation of myosin regulatory light chains is involved in breaking these interactions, activating the thick filaments by disordering and releasing the myosin heads, enabling their interaction with thin filaments. This atomic model has opened the way to the understanding of the molecular mechanism of the myosin-linked regulation of striated muscle contraction
Disciplinas: Biología,
Química
Palabras clave: Artrópodos,
Fisiología animal,
Bioquímica,
Músculo estriado,
Arachnida,
Microscopía,
Miosina,
Biología molecular
Keyword: Biology,
Chemistry,
Animal physiology,
Arthropods,
Biochemistry,
Striated muscle,
Arachnida,
Microscopy,
Myosin,
Molecular biology
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