The use of proteins, nucleic acids or complete cells as genetically encodable and engineerable molecular tools becomes increasingly important. One of the most prolific areas is the construction of labels and sensors for in vivo and in situ imaging (e.g. fluorescent protein based).
The research group for Molecular Engineering focuses on enabling this rich variety of tools for opto-acoustic (OA) imaging. OA is an emerging methodology bridging light excitation and ultrasound detection towards deep tissue imaging. The physical concept of this technique requires exclusively tailored labels aiming, contrary to their counterparts in fluorescence imaging, for a maximization of the non-radiative decay channel. Moreover, the deeper penetration depth of OA and the potential existence of strong absorbers (e.g. blood) call for an eye for infrared applicability.
Regarding the sensor side we adapt existing molecular sensors for OA usage and aim for innovative small molecule sensors to study neuronal functioning. Due to the close relation of fluorescence and OA imaging such novel sensors are mutually beneficial to both modalities. Beyond that we push and exploit the modularity of building blocks (e.g. label and receptor) towards a combination of visualization, interaction and downstream effect.
Conclusively we are interested in the detailed functioning of our tools on a molecular level pushing our understanding towards true top-down-engineering approaches.
The group combines methods of screening-based and rational (computational) molecular engineering with biophysical and in vivo validation of the tools as well as structural elucidation of their mechanism. We draw expertise from structural-, molecular-, cell- and chemical biology as well as biophysics.
Mishra K, Fuenzalida Werner JP, Ntziachristos V, Stiel AC. Photo-Controllable Proteins for Optoacoustic Imaging. Anal Chem. 2019 Apr 1. Link to online version: doi: 10.1021/acs.analchem.9b01048
Peters L., Weidenfeld I., Klemm U., Loeschcke A., Weihmann R., Jaeger K-E., Drepper T., Ntziachristos V. & Stiel A.C. Phototrophic purple bacteria as optoacoustic in vivo reporters of macrophage activity. Nature Communications volume 10, Article number: 1191, 2019
Gujrati V., Prakash J., Malekzadeh-Najafabadi J., Stiel A., Klemm U., Mettenleiter G., Aichler M., Walch A., Ntziachristos V. Bioengineered bacterial vesicles as biological nano-heaters for optoacoustic imaging. Nature Communications volume 10, Article number: 1114, 2019
Fuenzalida-Werner J.P., Janowski R., Mishra K., Weidenfeld I., Niessing, D., Ntziachristos V., Stiel A.C. Crystal structure of a biliverdin-bound phycobiliprotein: interdependence of oligomerization and chromophorylation. Journal of Structural Biology, 2018
Vetschera P., Mishra K., Fuenzalida-Werner J.P., Chmyrov A., Ntziachristos V., Stiel A.C. Characterization of Reversibly Switchable Fluorescent Proteins in Optoacoustic Imaging. Anal. Chem. Sep 4;90(17):10527-10535, 2018
Stiel A.C., Deán-Ben X.L., Jiang Y., Ntziachristos V., Razansky D. and Westmeyer G.G. High-contrast imaging of reversibly switchable fluorescent proteins via temporally unmixed multispectral optoacoustic tomography. Optics Letters 40(3):367-370, 2015
Deán-Ben XL, Stiel AC, Jiang Y, Ntziachristos V, Westmeyer GG, Razansky D. Light fluence normalization in turbid tissues via temporally unmixed multispectral optoacoustic tomography. Optics Letters 40(20):4691-4694, 2015
Key publications Andre C. Stiel
Brakemann T.*, Stiel A.C.*, Weber G., Andresen M., Testa I., Grotjohann T., Leutenegger M., Plessmann U., Urlaub H., Eggeling C., Wahl M.C., Hell S.W. and S. Jakobs. A reversibly photoswitchable GFP-like protein with fluorescence excitation decoupled from switching. Nat. Biotechnol. 29(10) 942-947. 2015 *shared first authorship
Stiel, A. C., Andresen M., Bock H., Hilbert M., Schilde J., Schönle A., Eggeling C., Egner A., Hell S.W. and S. Jakobs. Generation of Monomeric Reversibly Switchable Red Fluorescent Proteins for Far-Field Fluorescence Nanoscopy. Biophys. J. 95(6) 2989-2997. 2008
Andresen, M., Stiel A.C., Fölling J., Wenzel D., Schönle A., Egner A., Eggeling C., Hell S.W. and S. Jakobs. Novel photoswitchable fluorescent proteins enable monochromatic multilabel imaging and dual color fluorescence nanoscopy. Nat. Biotechnol. 26(9) 1035-1040. 2008.
Andresen, M.*, Stiel A.C.*, Trowitzsch S., Weber G., Eggeling C., Wahl M.C., Hell S.W. and S. Jakobs. Structural basis for reversible photoswitching in Dronpa. Proc. Natl. Acad. Sci. U. S. A. 104(32): 13005-13009. 2007. * shared first authorship.
Stiel, A. C., Trowitzsch S. , Weber G. , Andresen M., Eggeling C., Hell S.W., Jakobs S. and M. C. Wahl. 1.8 A bright-state structure of the reversibly switchable fluorescent protein Dronpa guides the generation of fast switching variants. Biochem. J. 402(1): 35-42. 2007.