PSD-95 assembles a ternary complex with the N-methyl-D-aspartic acid receptor and a bivalent neuronal NO synthase PDZ domain

• Published in: The Journal of biological chemistry 1999-09, Vol.274 (39), p.27467-27473
• Main Authors: Christopherson, K S, Hillier, B J, Lim, W A, Bredt, D S
• Format: Article
• Language: English
• Subjects: Animals; Binding Sites; Cell Line; Cell Membrane - physiology; Cell Membrane - ultrastructure; Circular Dichroism; Cloning, Molecular; Disks Large Homolog 4 Protein; Guanidine - pharmacology; Humans; Intracellular Signaling Peptides and Proteins; Macromolecular Substances; Membrane Proteins; Models, Molecular; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - metabolism; Nitric Oxide Synthase - chemistry; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type I; postsynaptic density 95 protein; Prosencephalon - metabolism; Protein Conformation; Rats; receptor clustering; Receptors, N-Methyl-D-Aspartate - chemistry; Receptors, N-Methyl-D-Aspartate - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Transfection
• ISSN: 0021-9258
• DOI: 10.1074/jbc.274.39.27467

Nitric oxide (NO) biosynthesis in cerebellum is preferentially activated by calcium influx through N-methyl-D-aspartate (NMDA)-type glutamate receptors, suggesting that there is a specific link between these receptors and neuronal NO synthase (nNOS). Here, we find that PSD-95 assembles a postsynaptic protein complex containing nNOS and NMDA receptors. Formation of this complex is mediated by the PDZ domains of PSD-95, which bind to the COOH termini of specific NMDA receptor subunits. In contrast, nNOS is recruited to this complex by a novel PDZ-PDZ interaction in which PSD-95 recognizes an internal motif adjacent to the consensus nNOS PDZ domain. This internal motif is a structured "pseudo-peptide" extension of the nNOS PDZ that interacts with the peptide-binding pocket of PSD-95 PDZ2. This asymmetric interaction leaves the peptide-binding pocket of the nNOS PDZ domain available to interact with additional COOH-terminal PDZ ligands. Accordingly, we find that the nNOS PDZ domain can bind PSD-95 PDZ2 and a COOH-terminal peptide simultaneously. This bivalent nature of the nNOS PDZ domain further expands the scope for assembly of protein networks by PDZ domains.