The SFB 1078 kindly invites you to the following colloquium talks:

1. Prof. Ana Damjanovic 

Title: New mechanism of ion channel selectivity

2. Prof. Clemens Glaubitz

Title: Light-induced adaptation, oligomer- and lipid interactions of membrane proteins

The Glaubitz Lab works on photoreceptors (1-4), membrane-based photochemical tools (5) as well as ABC transporters and GPCRs (6,7). The methodological approach is centered around solid-state NMR spectroscopy in combination dynamic nuclear polarization. This research lecture will focus on our work on native and artificial photoswitches in form of light- driven ion pumps and photolipids. Microbial rhodopsins such as proteorhodopsins show a high degree of environmental adaptation by optimizing their absorption maximum. It will be demonstrated how biochemical data in combination with solid-state NMR and QM/MM approaches have been used to disentangle the factors which determine the remarkable sequence-dependent color shifts in this protein family, which is required to maintain their ion pumping activity (1). Furthermore, specific, light-induced interactions at the protomer interfaces in these pentameric complexes during the photocycle will be described and discussed (2-4). In the context of artificial photoswitches, the effect of photoswitchable lipids (AzoPC) onto lipid membranes and functional structural properties of embedded proteins will be described (5).

(1) Mao, J. et al. submitted & Mao, J. et al. Structural basis of the green-blue color switching in proteorhodopsin as determined by NMR spectroscopy. J. Am. Chem. Soc. 136, 17578-17590, doi:10.1021/ja5097946 (2014).

(2) Jakdetchai, O. et al. Probing the photointermediates of light-driven sodium ion pump KR2 by DNP-enhanced solid-state NMR. Sci Adv 7, doi:10.1126/sciadv.abf4213 (2021).

(3) Mehler, M. et al. Chromophore Distortions in Photointermediates of Proteorhodopsin Visualized by Dynamic Nuclear Polarization-Enhanced Solid-State NMR. J. Am. Chem. Soc. 139, 16143-16153, doi:10.1021/jacs.7b05061 (2017).

(4) Maciejko, J., Kaur, J., Becker-Baldus, J. & Glaubitz, C. Photocycle-dependent conformational changes in the proteorhodopsin cross-protomer Asp-His-Trp triad revealed by DNP-enhanced MAS-NMR. Proc Natl Acad Sci U S A 116, 8342-8349, doi:10.1073/pnas.1817665116 (2019).

(5) Doroudgar, M., Morstein, J., Becker-Baldus, J., Trauner, D. & Glaubitz, C. How Photoswitchable Lipids Affect the Order and Dynamics of Lipid Bilayers and Embedded Proteins. J. Am. Chem. Soc. 143, 9515-9528, doi:10.1021/jacs.1c03524 (2021).

(6) Kaur, H. et al. Coupled ATPase-adenylate kinase activity in ABC transporters. Nature communications 7, 13864, doi:10.1038/ncomms13864 (2016).

(7) Joedicke, L. et al. The molecular basis of subtype selectivity of human kinin G- protein-coupled receptors. Nat. Chem. Biol. 14, 284-290, doi:10.1038/nchembio.2551 (2018).

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