Beck-Sickinger/Seitz

Fluorescently labeled proteins enable the microscopic imaging of protein localization and function in live cells. The fluorophore is introduced either as autofluorescent protein or by means of labeling reactions targeted against specific tag sequences. Of major concern is the size of the fluorophore-tag. The tag should be small to prevent interference with protein function. We will develop a bioorthogonal labeling reaction that allows the introduction of virtually any reporter group, requires only small tag sequences (max 23 aa), occurs with high tag specificity and proceeds within minutes (rather than hours). High reaction rates are required in pulse chase experiments, which allow the analysis of receptor internalization in living cells. 

To achieve the goals, we will take advantage of peptide-templated reactions. A cysteine-containing acceptor tag will be fused to the protein of interest. A second, so-called donor peptide binds the acceptor with nanomolar affinity. This interaction triggers the transfer of a thioester- or sulfonate-linked reporter group from the donor peptide to the acceptor peptide. The acceptor peptides will be fused to recombinantly expressed proteins (adiponectin), membrane proteins with extracellular (e. g. neuropeptide Y2 receptor) or intracellular (e. g. adiponectin receptor 1) tags. Biotinylation will facilitate the purification. Rapid fluorescence labeling at the N-terminus of membrane proteins will enable studies of protein trafficking by pulse-chase experiments.

U. Reinhardt, J. Lotze, K. Mörl, A.G. Beck-Sickinger, O. Seitz
Bioconjug. Chem. 2015, 26, 2106-2117
Rapid Covalent Fluorescence Labeling of Membrane Proteins on Live Cells via Coiled-Coil Templated Acyl Transfer.
Link to the article

V. te Kamp, H.-G. Jahnke, D. Krinke, K.B. Kostelnik, A.G. Beck-Sickinger, A.A. Roblitzki
Biosens Bioelectron 2014, 14, 662-669
Quantitative impedimetric NPY-receptor activation monitoring and signaling profiling in living cells.
Link to the article

V. Mäde, K. Bellmann-Sickert, A. Kaiser, J. Meiler, A.G. Beck-Sickinger
ChemMedChem 2014, 9, 2463-2474
Position and length of fatty acids strongly affect receptor selectivity pattern of human pancreatic polypeptide analogues.
Link to the article

U. Reinhardt, J. Lotze, S. Zernia, K. Mörl, A.G. Beck-Sickinger, O. Seitz
Angew. Chem. Int. Ed.2014, 53, 10237-10241.
Peptide-templated acyl transfer: a chemical method for the labeling of membrane proteins.
Link to the article

V. Mäde, S. Babilon, N. Jolly, L. Wanka, K. Bellmann-Sickert, L.E. Diaz Gimenez, K. Mörl, H.M. Cox, V.V. Gurevich, A.G. Beck-Sickinger
Angew. Chem. Int. Ed.2014, 53, 10067-10071
Peptide modifications differentially alter G protein-coupled receptor internalization and signaling bias.
Link to the article