PDBsum entry 2r09

Signaling protein

PDB id: 2r09

Contents

Protein chains

343 a.a. *

Ligands

SO4 ×7

4IP ×2

PGE

PE5

Waters ×807

* Residue conservation analysis

PDB id:

2r09

Name:

Signaling protein

Title:

Crystal structure of autoinhibited form of grp1 arf gtpase exchange factor

Structure:

Cytohesin-3. Chain: a, b. Fragment: sec7 domain 2 (residues 63-399). Synonym: ph, sec7 and coiled-coil domain-containing protein 3, clm3, sec7 homolog c, msec7-3, arf nucleotide-binding site opener 3, protein arno3, general receptor of phosphoinositides 1, grp1. Engineered: yes. Mutation: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Gene: pscd3, grp1. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.90Å R-factor: 0.206 R-free: 0.241

Authors:

J.P.Dinitto,A.Delprato,M.T.Gabe Lee,T.C.Cronin,S.Huang,A.Guilherme, M.P.Czech,D.G.Lambright

Key ref:

J.P.DiNitto et al. (2007). Structural basis and mechanism of autoregulation in 3-phosphoinositide-dependent Grp1 family Arf GTPase exchange factors. Mol Cell, 28, 569-583. PubMed id: 18042453 DOI: 10.1016/j.molcel.2007.09.017

Date:

17-Aug-07 Release date: 04-Dec-07

Protein chains

O08967  (CYH3_MOUSE) -  Cytohesin-3 from Mus musculus

Seq: 399 a.a.

Struc: 343 a.a.*

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

DOI no: 10.1016/j.molcel.2007.09.017

Mol Cell 28:569-583 (2007)

PubMed id: 18042453

Structural basis and mechanism of autoregulation in 3-phosphoinositide-dependent Grp1 family Arf GTPase exchange factors.

J.P.DiNitto, A.Delprato, M.T.Gabe Lee, T.C.Cronin, S.Huang, A.Guilherme, M.P.Czech, D.G.Lambright.

ABSTRACT

Arf GTPases regulate membrane trafficking and actin dynamics. Grp1, ARNO, and Cytohesin-1 comprise a family of phosphoinositide-dependent Arf GTPase exchange factors with a Sec7-pleckstrin homology (PH) domain tandem. Here, we report that the exchange activity of the Sec7 domain is potently autoinhibited by conserved elements proximal to the PH domain. The crystal structure of the Grp1 Sec7-PH tandem reveals a pseudosubstrate mechanism of autoinhibition in which the linker region between domains and a C-terminal amphipathic helix physically block the docking sites for the switch regions of Arf GTPases. Mutations within either element result in partial or complete activation. Critical determinants of autoinhibition also contribute to insulin-stimulated plasma membrane recruitment. Autoinhibition can be largely reversed by binding of active Arf6 to Grp1 and by phosphorylation of tandem PKC sites in Cytohesin-1. These observations suggest that Grp1 family GEFs are autoregulated by mechanisms that depend on plasma membrane recruitment for activation.

Selected figure(s)

Figure 3.
Figure 3. Pseudosubstrate Autoinhibition by the Sec7-PH Linker and C-Terminal Helix
(A) Intramolecular interactions at the interface between the linker and Sec7 domain.
(B) Intramolecular interactions at the interface between the C-terminal helix and Sec7 domain.
(C and D) Comparison of the linker and C-terminal helix of Grp1 with the switch I and II regions of Arf1-GDP from the complex with the E156K mutant of the ARNO Sec7 domain (PDB ID code 1R8S) after superposition of Cα atoms.

Figure 7.
Figure 7. Model for Autoregulation of Grp1 Family GEFs
After PtdIns(3,4,5)P[3]-dependent plasma membrane recruitment of Grp1 family GEFs, lateral association with Arf6-GTP simultaneously enhances membrane partitioning and shifts the equilibrium toward the catalytically competent conformation. Other mechanisms, including phosphorylation of PKC sites in the polybasic motif of Cytohesin-1, may be required for full activation.

The above figures are reprinted from an Open Access publication published by Cell Press: Mol Cell (2007, 28, 569-583) copyright 2007.

Figures were selected by an automated process.