Veranstaltungsort: FIAS Lecture Hall 0.100

Unsere nächste Ausgabe der "CMMS Talks" findet am Dienstag, 12.11.2024 um 11.00 Uhr in 0.100 statt. Sprechen wird Prof. Dr. Thomas T. Perkins.

Der Vortrag wird in englischer Sprache gehalten, daher sind die folgenden Informationen ebenfalls Englisch. 

Abstract:

The forces and energetics that stabilize membrane proteins remain elusive to precise quantification. Single-molecule force spectroscopy can yield kinetic rate constants, energetics, intermediate states, unfolding pathways, and even a projection of the underlying free-energy landscape. Using recently developed micromachined AFM cantilevers, we reexamined the unfolding of individual molecules of bacteriorhodopsin (bR) embedded in its native lipid bilayer with a 100-fold improvement in time resolution and a 10-fold improvement in force precision. Numerous newly detected intermediates—many separated by as few as 2–3 amino acids—exhibited complex dynamics, including frequent refolding and state occupancies of <10 µs. To quantifying energetics, we leveraged the rapid and reversible initial unfolding of bR to determine the free-energy change (ΔΔG₀) for select point mutants and thereby highlighted the importance of measuring membrane protein energetics in lipid bilayers rather than mixed micelles. In bR’s photocycle, photon absorption by retinal triggers a conformational cascade that results in pumping a proton across the cell membrane. By integrating sub-ms illumination with our AFM, we quantified the energetics of a light-induced change in bR’s photocycle. I will conclude by discussing extensions of these enhancements in bioAFM to other diverse biomolecules, including nucleic-acid structures and globular proteins involved in pathogenesis.

CMMS Project