Engineering paralog-specific PSD-95 recombinant binders as minimally interfering multimodal probes for advanced imaging techniques

Charlotte Rimbault, Christelle Breillat, Benjamin Compans, Estelle Toulmé, Filipe Nunes Vicente, Monica Fernandez-Monreal, Patrice Mascalchi, Camille Genuer, Virginia Puente-Muñoz, Isabel Gauthereau, Eric Hosy, Stéphane Claverol, Gregory Giannone, Ingrid Chamma, Cameron D Mackereth, Christel Poujol, Daniel Choquet, Matthieu Sainlos
eLife. 2024-01-03; 13:
DOI: 10.7554/eLife.69620

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Despite the constant advances in fluorescence imaging techniques, monitoring endogenous proteins still constitutes a major challenge in particular when considering dynamics studies or super-resolution imaging. We have recently evolved specific protein-based binders for PSD-95, the main postsynaptic scaffold proteins at excitatory synapses. Since the synthetic recombinant binders recognize epitopes not directly involved in the target protein activity, we consider them here as tools to develop endogenous PSD-95 imaging probes. After confirming their lack of impact on PSD-95 function, we validated their use as intrabody fluorescent probes. We further engineered the probes and demonstrated their usefulness in different super-resolution imaging modalities (STED, PALM and DNA-PAINT) in both live and fixed neurons. Finally, we exploited the binders to enrich at the synapse genetically encoded calcium reporters. Overall, we demonstrate that these evolved binders constitute a robust and efficient platform to selectively target and monitor endogenous PSD-95 using various fluorescence imaging techniques.

Auteurs Bordeaux Neurocampus