Intramolecular domain dynamics regulate synaptic MAGUK protein interactions

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Abstract

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.

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All relevant data generated or analysed during this study are included in the manuscript as source data files.

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Nils Rademacher

Neuroscience Research Center (NWFZ), Charité-Universitätsmedizin Berlin, Berlin, Germany

For correspondence
Nils.Rademacher@charite.de

Competing interests
The authors declare that no competing interests exist.
Benno Kuropka

Institute of Chemistry and Biochemistry/Protein Biochemistry, Freie Universität Berlin, Berlin, Germany

Competing interests
The authors declare that no competing interests exist.
Stella-Amrei Kunde

Neuroscience Research Center (NWFZ), Charité-Universitätsmedizin Berlin, Berlin, Germany

Competing interests
The authors declare that no competing interests exist.
Markus C Wahl

Institute of Chemistry and Biochemisty/Structural Biochemistry, Freie Universität Berlin, Berlin, Germany

Competing interests
The authors declare that no competing interests exist.
Christian Freund

Institute of Chemistry and Biochemistry/Protein Biochemistry, Freie Universität Berlin, Berlin, Germany

Competing interests
The authors declare that no competing interests exist.
Sarah Althea Shoichet

Neuroscience Research Center (NWFZ), Charité-Universitätsmedizin Berlin, Berlin, Germany

For correspondence
sarah.shoichet@charite.de

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-4933-7846

Funding

Deutsche Forschungsgemeinschaft (SFB958)

Markus C Wahl
Christian Freund
Sarah Althea Shoichet

Deutsche Forschungsgemeinschaft (SH650/2)

Sarah Althea Shoichet

Deutsche Forschungsgemeinschaft (EXC 257)

Sarah Althea Shoichet

Deutsche Forschungsgemeinschaft (SFB665)

Sarah Althea Shoichet

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: All animals used were handled in accordance with the relevant guidelines and regulations. Protocols were approved by the 'Landesamt für Gesundheit und Soziales' (LaGeSo; Regional Office for Health and Social Affairs) in Berlin and animals reported under the permit number T0280/10.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.