Dresden 2020 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 21: Cell Adhesion and Migration, Multicellular Systems I
BP 21.10: Vortrag
Mittwoch, 18. März 2020, 12:30–12:45, HÜL 386
Identifying the blue-light photoreceptor underlying light-switchable adhesion of Chlamydomonas to surfaces. — •Rodrigo Catalán1, Antoine Girot1, Theresa Büttner1, Alexandros Fragkopoulos1, Simon Kelterborn2, Peter Hegemann2, and Oliver Bäumchen1 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), Am Fassberg 17, 37077 Göttingen, Germany. — 2Humboldt University of Berlin, Institute of Biology, Invalidenstrasse 42, 10115 Berlin, Germany.
Photosynthetic microorganisms have developed several photoactive responses to spatial and temporal light variations. Interestingly, the unicellular, eukaryotic microalga Chlamydomonas reinhardtii swims freely in red light but exhibits flagella-mediated adhesion to surfaces when exposed to blue light (Kreis et al., Nature Physics, 2018). We performed adsorption experiments to establish the spectral sensitivity of the adhesiveness of wild-type Chlamydomonas and found a maximum of the cell adsorption rate at 470 nm. These results provide evidence that a blue-light photoreceptor triggers light-switchable adhesiveness. There are 18 known photoreceptors in Chlamydomonas, most of which are blue-light sensitive. We use targeted gene editing tools to establish photoreceptor-deletion mutants and perform adsorption experiments and complementary micropipette force spectroscopy experiments on these strains. We find that channelrhodopsin 1 and 2 as well as phototropin are not the functional photoreceptors mediating light-switchable adhesion, which is interesting since they account for other important responses, namely phototaxis and the cell’s life cycle.