Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 7: Superresolution Optical Microscopy (focus session)
BP 7.2: Vortrag
Montag, 16. März 2015, 15:00–15:15, H 1028
Molecular architecture of native fibronectin fibrils — •Ingmar Schoen1, Susanna Früh1, Jonas Ries2, and Viola Vogel1 — 1ETH Zurich, Zurich, Switzerland — 2European Molecular Biology Laboratory, Heidelberg, Germany
Fibronectin fibrils within the extracellular matrix play central roles in regulating cell anchorage and behavior, particularly in early development, wound healing, but also in cancer and other pathologies. However, their hierarchical structure at the molecular level remained elusive. Using single-molecule localization microscopy combined with site-specific labeling techniques, we found that the most elemental fibronectin protofibrils consist of overlapping dimeric fibronectin molecules that show a quasi-periodic order. The spatial autocorrelation of regular, punctate label patterns along these fibrils yielded an average spacing of ca. 95 nm which was consistent for different antibody epitopes along the fibronectin molecule. Dual-color cross-correlation revealed alternating N- and C-terminal regions. Single end-labeled fibronectin molecules incorporated into protofibrils displayed an average end-to-end distance of ca. 133 nm. Together, these results suggest a staggered arrangement with an antiparallel 30-40 nm broad overlap of the N-termini of adjacent molecules involving the first five type I and type III repeats of each molecule. While demonstrated here using fibronectin fibers, this powerful super-resolution approach can be extended to elucidate the build-up of other filamentous protein structures in their physiological environment.