Direct optical measurement of intramolecular distances with angstrom precision

Authors:

Steffen J. Sahl, Jessica Matthias, Kaushik Inamdar, Michael Weber, Taukeer A. Khan, Christian Brüser, Stefan Jakobs, Stefan Becker, Christian Griesinger, Johannes Broichhagen, and Stefan W. Hell

Keywords:

MINFLUX; angstrom; optical measurement; intramacromolecular; intramacromolecular distances; protein-protein interactions; polyproline ruler

Abstract:

Optical investigations of nanometer distances between proteins, their subunits, or other biomolecules have been the exclusive prerogative of Förster resonance energy transfer (FRET) microscopy for decades. In this work, we show that MINFLUX fluorescence nanoscopy measures intramolecular distances down to 1 nanometer—and in planar projections down to 1 angstrom—directly, linearly, and with angstrom precision. Our method was validated by quantifying well-characterized 1- to 10-nanometer distances in polypeptides and proteins. Moreover, we visualized the orientations of immunoglobulin subunits, applied the method in human cells, and revealed specific configurations of a histidine kinase PAS domain dimer. Our results open the door for examining proximities and interactions by direct position measurements at the intramacromolecular scale.

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