title: Actin bundles cross-linked with α-actinin studied by nanobeam X-ray diffraction.
abstract: We have performed scanning nano-beam small-angle X-ray scattering (nano-SAXS) experiments on in vitro-formed actin filaments cross-linked with [Formula: see text]-actinin. The experimental method combines a high resolution in reciprocal space with a real space resolution as given by the spot-size of the nano-focused X-ray beam, and opens up new opportunities to study local super-molecular structures of actin filaments. In this first proof-of-concept, we show that the local orientation of actin bundles formed by the cross-linking can be visualized by the X-ray darkfield maps. The filament bundles give rise to highly anisotropic diffraction patterns showing distinct streaks perpendicular to the bundle axes. Interestingly, some diffraction patterns exhibit a fine structure in the form of intensity modulations allowing for a more detailed analysis of the order within the bundles. A first empirical quantification of these modulations is included in the present work.
authors.affiliation: Institut für Röntgenphysik, Univ. Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Töpperwien
authors.affiliation: Institut für Röntgenphysik, Univ. Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Priebe
authors.affiliation: Institut für Röntgenphysik, Univ. Göttingen, Friedrich-Hund-Platz 1, 37077, Göttingen, Germany. tsaldit@gwdg.de.
authors.forename: T
authors.initials: T
authors.lastname: Salditt
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry*; D000185:Actinin / Q000737:chemistry*; D036103:Nanotechnology; D014961:X-Ray Diffraction
chemical_list: D000185:Actinin
keywords: -Actinin; Actin bundles; X-ray diffraction