PDBsum entry 2egk

Protein binding

PDB id: 2egk

Contents

Protein chains

89 a.a. *

90 a.a. *

Ligands

PO4 ×2

Waters ×43

* Residue conservation analysis

PDB id:

2egk

Name:

Protein binding

Title:

Crystal structure of tamalin pdz-intrinsic ligand fusion protein

Structure:

General receptor for phosphoinositides 1-associated scaffold protein. Chain: a, b, c, d. Fragment: pdz domain, c-terminal peptode(intrinsic ligand). Synonym: grp1-associated scaffold protein, tamalin, 95 kda postsynaptic density protein discs-large zo-1 domain-containing protein, psd-95 pdz domain-containing protein. Engineered: yes. Mutation: yes

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Tissue: brain. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693.

Resolution:

2.85Å R-factor: 0.269 R-free: 0.291

Authors:

T.Sugi,T.Oyama,T.Muto,S.Nakanishi,K.Morikawa,H.Jingami

Key ref:

T.Sugi et al. (2007). Crystal structures of autoinhibitory PDZ domain of Tamalin: implications for metabotropic glutamate receptor trafficking regulation. EMBO J, 26, 2192-2205. PubMed id: 17396155 DOI: 10.1038/sj.emboj.7601651

Date:

01-Mar-07 Release date: 08-May-07

Protein chains

Q8R4T5  (GRASP_RAT) -  General receptor for phosphoinositides 1-associated scaffold protein from Rattus norvegicus

Seq: 394 a.a.

Struc: 89 a.a.*

Protein chains

Q8R4T5  (GRASP_RAT) -  General receptor for phosphoinositides 1-associated scaffold protein from Rattus norvegicus

Seq: 394 a.a.

Struc: 90 a.a.*

* PDB and UniProt seqs differ at 11 residue positions (black crosses)

DOI no: 10.1038/sj.emboj.7601651

EMBO J 26:2192-2205 (2007)

PubMed id: 17396155

Crystal structures of autoinhibitory PDZ domain of Tamalin: implications for metabotropic glutamate receptor trafficking regulation.

T.Sugi, T.Oyama, T.Muto, S.Nakanishi, K.Morikawa, H.Jingami.

ABSTRACT

Metabotropic glutamate receptors (mGluRs) function as neuronal G-protein-coupled receptors and this requires efficient membrane targeting through associations with cytoplasmic proteins. However, the molecular mechanism regulating mGluR cell-surface trafficking remains unknown. We report here that mGluR trafficking is controlled by the autoregulatory assembly of a scaffold protein Tamalin. In the absence of mGluR, Tamalin self-assembles into autoinhibited conformations, through its PDZ domain and C-terminal intrinsic ligand motif. X-ray crystallographic analyses visualized integral parts of the oligomeric self-assemblies of Tamalin, which require not only the novel hydrophobic dimerization interface but also canonical and noncanonical PDZ/ligand autoinhibitory interactions. The mGluR cytoplasmic region can competitively bind to Tamalin at a higher concentration, disrupting weak inhibitory interactions. The atomic view of mGluR association suggests that this rearrangement is dominated by electrostatic attraction and repulsion. We also observed in mammalian cells that the association liberates the intrinsic ligand toward a motor protein receptor, thereby facilitating mGluR cell-surface trafficking. Our study suggests a novel regulatory mechanism of the PDZ domain, by which Tamalin switches between the trafficking-inhibited and -active forms depending on mGluR association.

Selected figure(s)

Figure 2.
Figure 2 mGluR binding disrupts the autoinhibitory assemblies of Tamalin to liberate the Intrinsic ligand. (A) Schematic representation of the domain structure of Tamalin. Molecules identified as binding partners and the series of constructs used in this study are depicted. (B, C) Yeast two-hybrid assays of hetero- (B) and homotypic (C) interactions of Tamalin. The independent mating cultures were spotted and then assayed for -gal activity. (D) Disruption of the autoinhibitory assembly of Tamalin by the binding of the mGluR5 C-terminal peptide. We utilized a pBridge vector (Clontech) instead of pAS2-1, in which the mGluR5 C-terminus was cloned or not into second multiple cloning site.

Figure 7.
Figure 7 Role of the electrostatic effect in the mGluR C-terminus/Tamalin PDZ domain interaction. Overall structure (A) and a close-up view (B) of the Tamalin PDZ-mGluR5 C-terminus complex. (A) The orientation of the PDZ dimers in the side view is identical to that in Figure 4A. (C) Electrostatic surface potential from approximately -10k[B] T^-1 (red) to +10k[B] T^-1 (blue). The negative charge of Glu114, which may contribute to the electrostatic interaction with mGluR5, is indicated by an arrow. (D) SPR analyses of the binding of the mGluRs and Tamalin C-termini to the Glu114Lys PDZ mutant.

The above figures are reprinted by permission from Macmillan Publishers Ltd: EMBO J (2007, 26, 2192-2205) copyright 2007.

Figures were selected by an automated process.