Stretching desmin filaments with receding meniscus reveals large axial tensile strength

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Abstract

Desmin forms the intermediate filament system of muscle cells where it plays important role in maintaining mechanical integrity and elasticity. Although the importance of intermediate-filament elasticity in cellular mechanics is being increasingly recognized, the molecular basis of desmin's elasticity is not fully understood. We explored desmin elasticity by molecular combing with forces calculated to be as large as 4. nN. Average filament contour length increased 1.55-fold axial on average. Molecular combing together with EGTA-treatment caused the fragmentation of the filament into short, 60 to 120-nm-long and 4-nm-wide structures. The fragments display a surface periodicity of 38. nm, suggesting that they are composed of laterally attached desmin dimers. The axis of the fragments may deviate significantly from that of the overstretched filament, indicating that they have a large orientational freedom in spite of being axially interconnected. The emergence of protofibril fragments thus suggests that the interconnecting head or tail domains of coiled-coil desmin dimers are load-bearing elements during axial stretch.

Original languageEnglish
Pages (from-to)472-480
Number of pages9
JournalJournal of Structural Biology
Volume186
Issue number3
DOIs
Publication statusPublished - Jun 2014

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Keywords

  • Atomic force microscopy
  • Desmin
  • Elasticity
  • Receding meniscus
  • Unit length filament

ASJC Scopus subject areas

  • Structural Biology

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