TY - JOUR TI - Fuzzy supertertiary interactions within PSD-95 enable ligand binding AU - Hamilton, George L AU - Saikia, Nabanita AU - Basak, Sujit AU - Welcome, Franceine S AU - Wu, Fang AU - Kubiak, Jakub AU - Zhang, Changcheng AU - Hao, Yan AU - Seidel, Claus AM AU - Ding, Feng AU - Sanabria, Hugo AU - Bowen, Mark E A2 - Kennedy, Mary B A2 - Dötsch, Volker A2 - Kennedy, Mary B A2 - Hendrix, Jelle A2 - Lee, Andrew VL - 11 PY - 2022 DA - 2022/09/07 SP - e77242 C1 - eLife 2022;11:e77242 DO - 10.7554/eLife.77242 UR - https://doi.org/10.7554/eLife.77242 AB - The scaffold protein PSD-95 links postsynaptic receptors to sites of presynaptic neurotransmitter release. Flexible linkers between folded domains in PSD-95 enable a dynamic supertertiary structure. Interdomain interactions within the PSG supramodule, formed by PDZ3, SH3, and Guanylate Kinase domains, regulate PSD-95 activity. Here we combined discrete molecular dynamics and single molecule Förster resonance energy transfer (FRET) to characterize the PSG supramodule, with time resolution spanning picoseconds to seconds. We used a FRET network to measure distances in full-length PSD-95 and model the conformational ensemble. We found that PDZ3 samples two conformational basins, which we confirmed with disulfide mapping. To understand effects on activity, we measured binding of the synaptic adhesion protein neuroligin. We found that PSD-95 bound neuroligin well at physiological pH while truncated PDZ3 bound poorly. Our hybrid structural models reveal how the supertertiary context of PDZ3 enables recognition of this critical synaptic ligand. KW - protein dynamics KW - single molecule fluorescence KW - postsynaptic density KW - FRET KW - discrete molecular dynamics simulations JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -