Structural basis for spinophilin-neurabin receptor interaction.
Neurabin and spinophilin are neuronal scaffolding proteins that play important roles in the regulation of synaptic transmission through their ability to target protein phosphatase 1 (PP1) to dendritic spines where PP1 dephosphorylates and inactivates glutamate receptors. However, thus far, it is still unknown how neurabin and spinophilin themselves are targeted to these membrane receptors. Spinophilin and neurabin contain a single PDZ domain, a common protein-protein interaction recognition motif, which are 86% identical in sequence. We report the structures of both the neurabin and spinophilin PDZ domains determined using biomolecular NMR spectroscopy. These proteins form the canonical PDZ domain fold. However, despite their high degree of sequence identity, there are distinct and significant structural differences between them, especially between the peptide binding pockets. Using two-dimensional 1H-15N HSQC NMR analysis, we demonstrate that C-terminal peptide ligands derived from glutamatergic AMPA and NMDA receptors and cytosolic proteins directly and differentially bind spinophilin and neurabin PDZ domains. This peptide binding data also allowed us to classify the neurabin and spinophilin PDZ domains as the first identified neuronal hybrid class V PDZ domains, which are capable of binding both class I and II peptides. Finally, the ability to bind to glutamate receptor subunits suggests that the PDZ domains of neurabin and spinophilin are important for targeting PP1 to C-terminal phosphorylation sites in AMPA and NMDA receptor subunits.
Kelker
Matthew S
MS
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, 70 Ship Street, Box G-E3, Providence, Rhode Island 02912, USA.
Dancheck
Barbara
B
Ju
Tingting
T
Kessler
Rene P
RP
Hudak
Jebecka
J
Nairn
Angus C
AC
Peti
Wolfgang
W
D000595:Amino Acid Sequence; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D000099273:Neurabins
D008840:Microfilament Proteins; D009419:Nerve Tissue Proteins; D000099273:Neurabins