PDBsum entry 2byv

Regulation

PDB id: 2byv

Contents

Protein chain

922 a.a. *

Waters ×66

* Residue conservation analysis

PDB id:

2byv

Name:

Regulation

Title:

Structure of the camp responsive exchange factor epac2 in its auto- inhibited state

Structure:

Rap guanine nucleotide exchange factor 4. Chain: e. Synonym: camp-regulated guanine nucleotide exchange factor ii, camp- gefii, exchange factor directly activated by camp 2, epac 2, camp- dependent rap1 guanine-nucleotide exchange factor. Engineered: yes

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.70Å R-factor: 0.248 R-free: 0.297

Authors:

H.Rehmann,A.Wittinghofer,J.L.Bos

Key ref:

H.Rehmann et al. (2006). Structure of the cyclic-AMP-responsive exchange factor Epac2 in its auto-inhibited state. Nature, 439, 625-628. PubMed id: 16452984 DOI: 10.1038/nature04468

Date:

08-Aug-05 Release date: 02-Feb-06

Protein chain

Q9EQZ6  (RPGF4_MOUSE) -  Rap guanine nucleotide exchange factor 4 from Mus musculus

Seq: 1011 a.a.

Struc: 922 a.a.

DOI no: 10.1038/nature04468

Nature 439:625-628 (2006)

PubMed id: 16452984

Structure of the cyclic-AMP-responsive exchange factor Epac2 in its auto-inhibited state.

H.Rehmann, J.Das, P.Knipscheer, A.Wittinghofer, J.L.Bos.

ABSTRACT

Epac proteins (exchange proteins directly activated by cAMP) are guanine-nucleotide-exchange factors (GEFs) for the small GTP-binding proteins Rap1 and Rap2 that are directly regulated by the second messenger cyclic AMP and function in the control of diverse cellular processes, including cell adhesion and insulin secretion. Here we report the three-dimensional structure of full-length Epac2, a 110-kDa protein that contains an amino-terminal regulatory region with two cyclic-nucleotide-binding domains and a carboxy-terminal catalytic region. The structure was solved in the absence of cAMP and shows the auto-inhibited state of Epac. The regulatory region is positioned with respect to the catalytic region by a rigid, tripartite beta-sheet-like structure we refer to as the 'switchboard' and an ionic interaction we call the 'ionic latch'. As a consequence of this arrangement, the access of Rap to the catalytic site is sterically blocked. Mutational analysis suggests a model for cAMP-induced Epac activation with rigid body movement of the regulatory region, the features of which are universally conserved in cAMP-regulated proteins.

Selected figure(s)

Figure 1.
Figure 1: Structure of Epac2. a, Domain organization of Epac. The same colour code is used throughout the figures. CDC25-HD, CDC25-homology domain; cNBD, cyclic-nucleotide-binding domain; DEP, Dishevelled, Egl-10, Pleckstrin domain; RA, Ras-association domain; REM, Ras-exchange motif. b, Ribbon diagram of Epac2 in stereo view. Missing connectivity is indicated by coloured dotted lines. The green ball indicates the cAMP-binding site in cNBD-B. HP, helical hairpin of the CDC25-HD (dark blue); SB, switchboard; IL, ionic latch (doted black lines); CH, connecting helix (helix H4 in ref 13). c, Surface representation of Epac. d, Superposition of Epac and the Ras-Sos complex. The RA, DEP and REM domains are omitted. Only Ras (magenta) from the Ras-Sos complex is shown.

Figure 2.
Figure 2: Anchoring points between the regulatory and catalytic regions. a, The switchboard is formed by strands provided by cNBD-B (dark green), the REM domain (orange) and the loop of the helical hairpin (HP) of CDC25-HD (blue). Peptides are reduced to polyglycine. Hydrogen bonding by main-chain atoms is indicated by dotted lines. b, The REM domain (orange) interacts tightly with the C-terminal helix of the helical hairpin (blue). Thick C traces highlight the parts of the switchboard shown in a. c, The ionic latch between cNBD-B (green) and CDC25-HD (blue). CH, connecting helix (see Fig. 1b).

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2006, 439, 625-628) copyright 2006.

Figures were selected by an automated process.