The PDZ1 domain of SAP90. Characterization of structure and binding.
The structural features of the PDZ1 domain of the synapse-associated protein SAP90 have been characterized by NMR. A comparison with the structures of the PDZ2 and PDZ3 domains of SAP90 illustrates significant differences, which may account for the unique binding properties of these homologous domains. Within the postsynaptic density, SAP90 functions as a molecular scaffold with a number of the protein-protein interactions mediated through the PDZ1 domain. Here, using fluorescence anisotropy and NMR chemical shift analysis, we have characterized the association of PDZ1 to the C-terminal peptides of the GluR6 subunit of the kainate receptor, voltage-gated K(+) channel Kv1.4, and microtubule-associate protein CRIPT, all of which are known to associate with SAP90. The latter two, which possess the consensus sequence for binding to PDZ domains (T/S-X-V-oh), have low micromolar binding affinities (1.5-15 microm). The C terminus of GluR6, RLPGKETMA-oh, lacking the consensus sequence, binds to PDZ1 of SAP90 with an affinity of 160 microm. The NMR data illustrate that although all three peptides occupy the binding groove capped by the GLGF loop of PDZ1, specific differences are present, consistent with the variation in binding affinities.
Piserchio
Andrea
A
Department of Chemistry, Division of Biology and Medicine, Brown University, Providence, RI 02912, USA.
Pellegrini
Maria
M
Mehta
Sunil
S
Blackman
Scott M
SM
Garcia
Elizabeth P
EP
Marshall
John
J
Mierke
Dale F
DF
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry; D003001:Cloning, Molecular; D000076122:Disks Large Homolog 4 Protein; D004305:Dose-Response Relationship, Drug; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D051665:Kv1.4 Potassium Channel; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry; D024642:Potassium Channels, Voltage-Gated; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D000074407:SAP90-PSD95 Associated Proteins; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C484742:Cript protein, rat; D000076122:Disks Large Homolog 4 Protein; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; C496979:Kcna4 protein, rat; D051665:Kv1.4 Potassium Channel; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010455:Peptides; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D000074407:SAP90-PSD95 Associated Proteins; C033652:postsynaptic density proteins