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Intramolecular domain dynamics regulate synaptic MAGUK protein interactions

Rademacher, Nils and Kuropka, Benno and Kunde, Stella-Amrei and Wahl, Markus C. and Freund, Christian and Shoichet, Sarah A. – 2019

PSD-95 MAGUK family scaffold proteins are multi-domain organisers of synaptic transmission that contain three PDZ domains followed by an SH3-GK domain tandem. This domain architecture allows coordinated assembly of protein complexes composed of neurotransmitter receptors, synaptic adhesion molecules and downstream signalling effectors. Here we show that binding of monomeric CRIPT-derived PDZ3 ligands to the third PDZ domain of PSD-95 induces functional changes in the intramolecular SH3-GK domain assembly that influence subsequent homotypic and heterotypic complex formation. We identify PSD-95 interactors that differentially bind to the SH3-GK domain tandem depending on its conformational state. Among these interactors, we further establish the heterotrimeric G protein subunit Gnb5 as a PSD-95 complex partner at dendritic spines of rat hippocampal neurons. The PSD-95 GK domain binds to Gnb5, and this interaction is triggered by CRIPT-derived PDZ3 ligands binding to the third PDZ domain of PSD-95, unraveling a hierarchical binding mechanism of PSD-95 complex formation.

Title
Intramolecular_Rademacher
Author
Rademacher, Nils and Kuropka, Benno and Kunde, Stella-Amrei and Wahl, Markus C. and Freund, Christian and Shoichet, Sarah A.
Date
2019-03-13
Identifier
10.7554/eLife.41299
Source(s)
Appeared in
eLife Sciences Publications - Volume 8, 2019
Language
eng
Type
Text