Project A2

Surface protonation and conformational dynamics in cytochrome c oxidase and photoreceptors

Principal Investigator: Prof. Dr. Ulrike Alexiev (FU)

The A2 project aims at elucidating protonation dynamics in relation to protein conformational changes on different time and length scales in the redox-linked proton pump cytochrome c oxidase (CcO) and in two photoreceptors, channelrhodopsin (ChR) and phytochrome, using time-resolved fluorescence and fluorescence correlation methods. Polarization-resolved and time-correlated single photon counting (TCSPC) in two temporal dimensions gives access to local structural dynamics. Site-directed fluorescence labeling of cysteine residues allows mapping of the respective proteins to gain information on local protonation and structural dynamics.


2017 - 2019

Balke, J., Volz, P., Neumann, F., Brodwolf, R., Wolf, A., Pischon, H., Radbruch, M., Mundhenk, L., Gruber, A. D., Ma, N., and Alexiev, U. (2018). Visualizing Oxidative Cellular Stress Induced by Nanoparticles in the Subcytotoxic Range using Fluorescence Lifetime Imaging. Small 14 (23), doi: 10.1002/smll.201800310.

Velazquez Escobar, F., Lang, C., Takiden, A., Schneider, C., Balke, J., Hughes, J., Alexiev, U., Hildebrandt, P., and Mroginski, M.A. (2017). Protonation-Dependent Structural Heterogeneity in the Chromophore Binding Site of Cyanobacterial Phytochrome Cph1. Journal of Physical Chemistry B 121, 47-57.

Wolf, A., Wonneberg, J., Balke, J., and Alexiev, U. (2019). Electronation-dependent structural change at the proton exit side of cytochrome c oxidase as revealed by site-directed fluorescence labeling. FEBS Journal, doi: 10.1111/febs.15084.

2013 - 2016

Alexiev, U., and Farrens, D.L. (2014). Fluorescence spectroscopy of rhodopsins: Insights and approaches. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1837, 694-709.

Kirchberg, K., Michel, H., and Alexiev, U. (2013). Exploring the entrance of proton pathways in cytochrome c oxidase from Paracoccus denitrificans: Surface charge, buffer capacity and redox-dependent polarity changes at the internal surface. Biochimica et Biophysica Acta (BBA) - Bioenergetics 1827, 276-284.

Richter, C., Schneider, C., Quick, M.T., Volz, P., Mahrwald, R., Hughes, J., Dick, B., Alexiev, U., and Ernsting, N.P. (2015). Dual-fluorescence pH probe for bio-labelling. Physical Chemistry Chemical Physics 17, 30590-30597.

Volz, P., Boreham, A., Wolf, A., Kim, T.-Y., Balke, J., Frombach, J., Hadam, S., Afraz, Z., Rancan, F., Blume-Peytavi, U., Vogt, A., and Alexiev, U. (2015). Application of Single Molecule Fluorescence Microscopy to Characterize the Penetration of a Large Amphiphilic Molecule in the Stratum Corneum of Human Skin. International Journal of Molecular Sciences 16, 6960-6977.

Volz, P., Krause, N., Balke, J., Schneider, C., Walter, M., Schneider, F., Schlesinger, R., and Alexiev, U. (2016). Light and pH-induced changes in structure and accessibility of transmembrane helix B and its immediate environment in Channelrhodopsin-2. Journal of Biological Chemistry 291, 17382-17393.

Wolf, A., Schneider, C., Kim, T.Y., Kirchberg, K., Volz, P., and Alexiev, U. (2016). A simulation-guided fluorescence correlation spectroscopy tool to investigate to protonation dynamics of cytrochrome c oxidase. Physical Chemistry Chemical Physics 18, 12877-12885.