Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 22: Posters: Cytoskeletal filaments
BP 22.2: Poster
Dienstag, 17. März 2015, 14:00–16:00, Poster A
Small Angle X-ray Scattering and Scanning X-Ray Nano-Diffraction on Keratin: Structural Changes Induced by Ions — •Clément Hémonnot1, Oliva Saldanha1, Rita Graceffa1, Harald Herrmann2, Britta Weinhausen3, Manfred Burghammer3, and Sarah Köster1 — 1Institute for X-Ray Physics, University of Göttingen, Germany — 2Division of Molecular Genetics, DKFZ, Heidelberg, Germany — 3ESRF, Grenoble, France
Keratin intermediate filament proteins play an important role for cell mechanics as they form extended filaments and complex, highly ordered intracellular networks, which provide integrity and stability to epithelial cells. We present bulk small angle X-ray scattering (SAXS) experiments as well as scanning X-ray nano-diffraction of bundles on Si3N4 windows, where we analyze single diffraction patterns with respect to orientation and ordering. We find that the addition of K+ or Mg2+ initiates bundle formation of the keratin filaments. As SAXS is a very sensitive technique that reveals structures on the nanometer length scale, we investigate the impact of K+ and Mg2+ ions on the internal structure of keratin filaments and assemblies. We demonstrate that the filaments assembled in presence of K+ or Mg2+ are similar and the evolution of the radius of core filaments is following a linear trend with the ion concentration. However, the effect of Mg2+ occurs at smaller concentrations than for K+, which could be due to ionic strength, and additionally leads to slightly thicker filaments. These experiments provide new insights into keratin assembly induced by K+ and Mg2+ on the nanometer scale.