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

Prof Irene Coin

Biochemistry and Protein Chemistry, Leipzig University, DE

Title: Genetic code expansion for structural and dynamic studies of membrane receptors in living cells

Abstract: 

We apply genetically encoded non-canonical amino acids (ncAAs) to address general questions about functioning of G protein-coupled receptors (GPCRs) directly from the natural environment of the live mammalian cell.

On one hand, we use photo-and chemical crosslinking amino acids [1] to define the topology of GPCR interactions both with ligands (especially peptide ligands) [2] and intracellular partners [3].

On the other hand, we have engineered enhanced tRNAs that have enabled efficient incorporation of last generation ncAAs for bioorthogonal chemistry into challenging protein targets [4]. In this way, we could achieve quantitative single-residue labeling of sensitive GPCR regions, such as the loops, with small organic fluorescent probes [5] and put the basis for the development of small-size fluorescent sensors for in-cell studies of GPCR dynamics.

[1] Coin I*. Curr. Opin. Chem. Biol., 2018, 46:156-163.

[2] Seidel L, Zarzycka B, Zaidi SA, Katritch V*, Coin I*. eLIFE, 2017, 6, 27711.

[3] Aydin Y, Böttke T, Lam JH, Ernicke S, Fortmann A, Tretbar M, Zarzycka B, Gurevich VV, Katritch V*, Coin I*. Nat. Commun. 2023, 14:1151.

[4] Serfling R, Lorenz C, Etzel M, Schicht G, Böttke T, Mörl M, Coin I*. Nucleic Acids Res. 2018, 46, 1-10 (2018).

[5] Serfling R, Seidel L, Bock A, Lohse MJ, Annibale P, Coin I*. ACS Chem. Biol. 2019, 14:1141-1149.

Supported by DFG grants CO822/2-1 (Emmy Noether), CO822/3-1, CO822/3-2, and CRC 1423, project number 421152132, subproject B04 to IC.

Prof Benjamin Kaupp

Senior-Professor am LIMES-Institut der Universität Bonn & Clausius-Institute of Physical and Theoretical Chemistry, University of Bonn, and Max-Planck Institute MPINAT, Göttingen, DE

Title: Sperm chemotaxis – signaling at the physical limit

Abstract: 

Sperm from marine invertebrates navigate to the egg in a chemoattractant gradient. The sperm flagellum serves as an antenna that registers the chemoattractant, as a motor that propels the cell, and as a rudder that steers sperm in the chemical landscape. Sperm are exquisitely sensitive: they can register the binding of a single chemoattractant molecule and translate binding events into a Ca²⁺ response that controls the flagellar beat and, thereby, the steering response. I will discuss the cGMP-signaling pathway that endows sperm with single-molecule sensitivity.

The dynamics of cellular responses, including changes in voltage, pH_i, and Ca²⁺, is optically recorded in motile sperm using rapid kinetic techniques including caged compounds. We find that, during navigation, sperm perform a surprisingly rich variety of computational operations; they can count, differentiate, integrate, and reset the signaling pathway. Furthermore, we decipher how such cell algebra is embodied by biochemical and electrical mechanisms.