Topological Structure of Smooth-Muscle TITIN Molecules and Oligomers

Yakupova, E.I.; Vikhlyantsev, I.M.; Bobylev, A.G.; Mártonfalvi, Z.; Kellermayer, M.S.

Авторы: Yakupova Elmira I., Vikhlyantsev Ivan M., Bobylev Alexander G., Mártonfalvi Zsolt, Kellermayer Miklós S.
Журнал: Biophysical Journal
Том: 118
Номер: 3
Год издания: 2020
Издательство: Biophysical Society
Местоположение издательства: United States
Первая страница: 496a
Последняя страница: 496a
DOI: 10.1016/j.bpj.2019.11.2742
Аннотация: Smooth-muscle titin (smitin) is a megadalton-size filamentous protein which is thought to play an important role in the structural organization of the contractile apparatus in smooth-muscle cells. The exact structure and interactions of smitin, however, are not fully known. In the present work we investigated the topological structure of smitin molecules and oligomers by using atomic force microscopy (AFM). Smitin was purified from chicken gizzard by employing procedures used for isolating titin from striated muscle. The final chromatography step of the purification procedure allowed us to partially separate smitin molecules from oligomeric species. The AFM topography of smitin molecules and oligomers was investigated on samples adsorbed to freshly cleaved mica, under dried conditions. Smitin molecules appeared as straight filaments with a mean contour length of 292 nm and with a head-like globular structure at one end. Among the oligomeric forms, we were able to distinguish two types: head-to-head oligomers and striped fiaments. The head-to-head oligomers displayed a Medusa-head-like structure in which smitin monomers are associated to each other via their globular head. The striped filaments were up to 2 microns long with stripes caused by the periodic arrangement of bead doublets along their axis. The bead-doublet spacing is 26 nm, whereas the periodicity of the bead doublets is 105 nm. Sometimes smitin monomers appeared radiating from the beads, suggesting that the striped filaments arise from the axial and lateral association of smitin monomers. Conceivably, the striped smitin filaments represent a supramolecular system that assists in the spatial organization of the smooth-muscle cell cytoskeleton. Supported by Higher Education Institutional Excellence Program of Ministry of Human Capacities, Hungary, within the therapy theme of Semmelweis-University.
Добавил в систему: Якупова Эльмира Ильдаровна

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Topological Structure of Smooth-Muscle TITIN Molecules and Oligomersстатья