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bioRxiv · 10.1101/2022.05.30.493832

Deciphering the conformational dynamics of gephyrin-mediated collybistin activation

Imam, N.·Choudhury, S.·Hemmen, K.·Heinze, K.·Schindelin, H.
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Abstract

Efficient neuronal signaling depends on the proper assembly of the postsynaptic neurotransmitter machinery and at inhibitory GABAergic synapses is controlled by the scaffolding protein gephyrin and collybistin, a Dbl-family guanine nucleotide exchange factor and neuronal adaptor protein. Collybistin usually contains an N-terminal SH3 domain and exists in closed/inactive or open/active states. Here, we elucidate the molecular basis of the gephyrin-collybistin interaction with newly designed collybistin FRET sensors. Using fluorescence lifetime-based FRET measurements, we deduce the affinity of the gephyrin-collybistin complex, thereby confirming that the C-terminal dimer-forming E domain binds collybistin, an interaction, which does not require E domain dimerization. Simulations based on fluorescence lifetime and sensor distance distributions reveal a dynamic behavior of the SH3 domain already in the closed state of collybistin. Finally, our data provide strong evidence for a collybistin-gephyrin communication network, where, unexpectedly, switching of collybistin from closed/inactive to open/active states is efficiently triggered by gephyrin.

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Imam, N., Choudhury, S., Hemmen, K., Heinze, K., Schindelin, H.. 2022-05-30. Deciphering the conformational dynamics of gephyrin-mediated collybistin activation. https://doi.org/10.1101/2022.05.30.493832

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