Regensburg 2022 – scientific programme

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BP: Fachverband Biologische Physik

BP 9: Bioimaging

BP 9.10: Talk

Tuesday, September 6, 2022, 12:15–12:30, H16

Studying biomolecular dynamics and structure with high-speed atomic force microscopy — •Dimitar Stamov, Andreas Kraus, André Körnig, and Heiko Haschke — JPK BioAFM, Bruker Nano GmbH, Am Studio 2D, 12489 Berlin, Germany

Studying the molecular dynamics and structural conformations is important for understanding the function and biological significance of samples ranging from single membrane proteins to complex macromolecular systems. Recent atomic force microscopy (AFM) developments have led to unprecedented imaging rates in fluid, enabling temporal resolution on the sub-20-milisecond scale.

Annexin V (A5) serves as an important regulator of membrane repair in eukaryotic cells, where it shows a strong Ca2+ binding affinity to phosphatidylserine. We have used high-speed AFM to study the 2D crystal formation in a model system containing supported lipid bilayers and A5 molecules. We demonstrate the lateral dynamics and preferred structural orientations of the mobile A5 trimers.

We previously demonstrated that pUC19 plasmids bind to poly-L-ornithine substrate in supercoiled states that are very high in torsional energy, thereby driving dehybridization of the double-helical DNA strands. Here we have quantified the process kinetics with a temporal resolution of 25 ms per frame and identified stages that include formation of metastable dehybridization bubbles, thermodynamic single strand fluctuations, and ultimately rehybridization to an intact double-stranded state.