Triggering Molecular Processes with Light (Prof. J. Wachtveitl)

  • Datum: 31.01.2017
  • Uhrzeit: 14:30 - 15:30
  • Vortragende(r): Prof. Dr. Josef Wachtveitl, Institute of Physical and Theoretical Chemistry, Frankfurt/M.
  • Raum: Herbert Walther Lecture Hall
  • Gastgeber: MPQ
Molecular systems that can be remotely controlled by light are gaining increasing importance in bio-sciences. High spatial and temporal precision is achievable with short laser pulses and in principle there are three approaches for light regulation.

Chromoproteins with built in photoswitches like rhodopsins can be directly photoactivated. The entire emerging field of optogentetics deals with ge-netically encoded light-sensitive proteins like channelrhodopsins1 that allow to specifically address even single neurons. Alternatively, one can use photolabile protecting groups to irreversibly trigger processes (uncaging) or photoswitches for reversible switching. My talk will focus on our recent pro-gress in these fields.
Caged puromycin represents an efficient photoactivatable antibiotic for in-cell applications that in-terferes with the translation process at the ribosome. UV illumination recovers the antibiotic activity of puromycin, the translation inhibition and polypeptide release triggered by uncaged puromycin are equivalent to the commercial compound2,3. We investigated the photodecarboxylation mechanism of the uncaging reaction by means of fs-IR spectroscopy and quantum chemical calculations and derived a reaction model that may serve as general guideline for improved ortho-nitrobenzyl cages4. Two-photon uncaging in a cellular context offers the advantage of higher penetration depth due to the longer excitation wavelength and a high spatial confinement of the photolysis area (1 fL).5 In bio-compatible hydrogels, the two-photon activation of photoactivatable glutathione triggers the inter-action with glutathione S-transferase and leads to a three-dimensional assembly of protein networks with high spatial resolution.6
Azobenzenes (AB) are a major class of photoswitches with photochromism based on the trans ↔ cis isomerization of their N=N bond. Suitably connected to biomolecules, azobenzenes can act as light trigger for initiation of conformational transitions. Time resolved spectroscopy provides a certain de-gree of structural information and allows following the kinetics of photoinduced conformational changes by investigating the transient, interconverting structures. Recent developments of light-responsive secondary and tertiary structures of peptides7, RNA8 and foldamers9 will be presented.

References:

(1) Neumann-Verhoefen, M.-K., Neumann, K., Bamann, C., Radu, I., Heberle, J., Bamberg, E. and Wachtveitl, J. (2013) Ultrafast infra-red spectroscopy on channelrhodopsin-2 reveals efficient energy transfer from the retinal chromophore to the protein, J. Am. Chem. Soc., 135, 6968-76
(2) Kohl-Landgraf, J., Buhr, F., Lefrancois, D., Mewes, J.M., Schwalbe, H., Dreuw, A. and Wachtveitl, J. (2014) Mechanism of the pho-toinduced uncaging reaction of puromycin protected by a 6-nitroveratryloxycarbonyl group, J. Am. Chem. Soc., 136, 3430-38
(3) Buhr, F., Kohl-Landgraf, J., Chatterjee, D., Hegelein, A., Wachtveitl, J. and Schwalbe H. (2015) Design of photocaged puromycin for nascent polypeptide release and spatiotemporal monitoring of translation, Angew. Chem. Int. Ed., 54, 3717-21
(4) Neumann, K., Verhoefen, M.-K., Mewes, J. M., Dreuw, A. and Wachtveitl, J. (2011) Investigating the CO2 uncaging mechanism of nitrophenylacetates by means of fs-IR spectroscopy and quantum chemical calculations, Phys. Chem. Chem. Phys., 13, 17367-77
(5) Fichte, M., Weyel, X., Junek, S., Schäfer, F., Herbivo, C., Goeldner, M., Specht, A., Wachtveitl, J. and Heckel, A. (2016) Three di-mensional control of DNA hybridisation by orthogonal two-color two-photon uncaging, Angew. Chem. Int. Ed., 55, 8948–52
(6) Gatterdam, V., Ramadass, R., Stoess, T., Wachtveitl, J., Heckel, A. and Tampé, R. (2014) Three-dimensional protein networks guided by two-photon activation, Angew. Chem. Int. Ed., 53, 5680-84
(7) Lorenz, L., Kusebauch, U., Moroder, L. and Wachtveitl, J. (2016) Temperature- and photo-controlled unfolding/folding of a triple-helical azobenzene-stapled collagen peptide monitored by infrared spectroscopy, ChemPhysChem, 17, 1314-20
(8) Goldau, T., Murayama, K., Brieke, C., Steinwand, S., Mondal, P., Biswas, M., Burghardt, I., Wachtveitl, J., Asanuma, H. and Heckel, A., (2015) Reversible photoswitching of RNA hybridization at room temperature with an azobenzene C-nucleoside, Chem. Eur. J., 21, 2845-54
(9) Steinwand, S., Yu, Z., Hecht, S. and Wachtveitl, J. (2016) Ultrafast dynamics of photoisomerization and subsequent unfolding of an oligo-azobenzene foldamer, J. Am. Chem. Soc., 138, 12997-13005

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