title: PSD-95 assembles a ternary complex with the N-methyl-D-aspartic acid receptor and a bivalent neuronal NO synthase PDZ domain.
abstract: 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.
authors.affiliation: Department of Physiology, and Program in Biomedical Sciences, University of California, San Francisco, California 94143-0444, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Christopherson
authors.forename: B J
authors.initials: BJ
authors.lastname: Hillier
authors.forename: W A
authors.initials: WA
authors.lastname: Lim
authors.forename: D S
authors.initials: DS
authors.lastname: Bredt
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D002942:Circular Dichroism; D003001:Cloning, Molecular; D000076122:Disks Large Homolog 4 Protein; D019791:Guanidine / Q000494:pharmacology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000737:chemistry / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D016548:Prosencephalon / Q000378:metabolism*; D011487:Protein Conformation; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014162:Transfection
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; C033652:postsynaptic density proteins; C496320:NOS1 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D019791:Guanidine