PDZ Ligand Binding-Induced Conformational Coupling of the PDZ–SH3–GK Tandems in PSD-95 Family MAGUKs

• Published in: Journal of molecular biology 2018-01, Vol.430 (1), p.69-86
• Main Authors: Zeng, Menglong, Ye, Fei, Xu, Jia, Zhang, Mingjie
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Disks Large Homolog 4 Protein - genetics; Guanylate Kinases - genetics; Humans; Intracellular Signaling Peptides and Proteins - genetics; Ligands; MAGUK; Membrane Proteins - genetics; Molecular Conformation; Nerve Tissue Proteins - genetics; PDZ; PDZ Domains - genetics; postsynaptic density; PSD-95; Rats; Receptors, Glutamate - genetics; Receptors, N-Methyl-D-Aspartate - genetics; src Homology Domains - genetics; synaptic signaling; Synaptic Transmission - genetics
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2017.11.003

Discs large (DLG) MAGUKs are abundantly expressed in glutamatergic synapses, crucial for synaptic transmission, and plasticity by anchoring various postsynaptic components including glutamate receptors, downstream scaffold proteins and signaling enzymes. Different DLG members have shared structures and functions, but also contain unique features. How DLG family proteins function individually and cooperatively is largely unknown. Here, we report that PSD-95 PDZ3 directly couples with SH3–GK tandem in a PDZ ligand binding-dependent manner, and the coupling can promote PSD-95 dimerization and multimerization. Aided by sortase-mediated protein ligation and selectively labeling, we elucidated the PDZ3/SH3–GK conformational coupling mechanism using NMR spectroscopy. We further demonstrated that PSD-93, but not SAP102, can also undergo PDZ3 ligand binding-induced conformational coupling with SH3–GK and form homo-oligomers. Interestingly, PSD-95 and PSD-93 can also form ligand binding-induced hetero-oligomers, suggesting a cooperative assembly mechanism for the mega-N-methyl-d-aspartate receptor synaptic signaling complex. Finally, we provide evidence showing that ligand binding-induced conformational coupling between PDZ and SH3–GK is a common feature for other MAGUKs including CASK and PALS1. [Display omitted] •PSD-95 PDZ3 conformationally couples with SH3–GK tandem in a PDZ ligand binding-dependent manner, and the coupling can promote PSD-95 dimerization and multimerization.•PDZ and SH3–GK conformational coupling is specific to PSD-95 and PSD-93 and does not occur in SAP102.•PSD-95 and PSD-93 can form ligand binding-induced hetero-oligomers, suggesting a cooperative assembly mechanism for the mega-NMDA receptor synaptic signaling complex.•Ligand binding-induced conformational coupling between PDZ and SH3–GK is a common feature for other MAGUKs including CASK and PALS1.