PDBsum entry 4hdo

Signaling protein

PDB id: 4hdo

Contents

Protein chains

310 a.a.

163 a.a.

Ligands

GOL

GNP

Metals

_MG

Waters ×268

PDB id:

4hdo

Name:

Signaling protein

Title:

Crystal structure of the binary complex of krit1 bound to the rap1 gtpase

Structure:

Krev interaction trapped protein 1. Chain: a. Fragment: ferm domain (unp residues 417-736). Synonym: krit1, krev interaction trapped 1, cerebral cavernous malformations 1 protein. Engineered: yes. Ras-related protein rap-1b. Chain: b. Fragment: unp residues 1-167.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: krit1, ccm1. Expressed in: escherichia coli. Expression_system_taxid: 469008. Gene: rap1b, ok/sw-cl.11.

Resolution:

1.67Å R-factor: 0.213 R-free: 0.231

Authors:

A.R.Gingras

Key ref:

A.R.Gingras et al. (2013). The structure of the ternary complex of Krev interaction trapped 1 (KRIT1) bound to both the Rap1 GTPase and the heart of glass (HEG1) cytoplasmic tail. J Biol Chem, 288, 23639-23649. PubMed id: 23814056 DOI: 10.1074/jbc.M113.462911

Date:

02-Oct-12 Release date: 10-Jul-13

Protein chain

O00522  (KRIT1_HUMAN) -  Krev interaction trapped protein 1 from Homo sapiens

Seq: 736 a.a.

Struc: 310 a.a.

Protein chain

P61224  (RAP1B_HUMAN) -  Ras-related protein Rap-1b from Homo sapiens

Seq: 184 a.a.

Struc: 163 a.a.

Enzyme reactions

• Enzyme class: Chain B: E.C.3.6.5.2 - small monomeric GTPase.
• Reaction: GTP + H2O = GDP + phosphate + H⁺

GTP + H2O = GDP (Bound ligand (Het Group name = GNP) matches with 81.82% similarity) + phosphate + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1074/jbc.M113.462911

J Biol Chem 288:23639-23649 (2013)

PubMed id: 23814056

The structure of the ternary complex of Krev interaction trapped 1 (KRIT1) bound to both the Rap1 GTPase and the heart of glass (HEG1) cytoplasmic tail.

A.R.Gingras, W.Puzon-McLaughlin, M.H.Ginsberg.

ABSTRACT

Loss of function mutation in Krev interaction trapped 1 (KRIT1) causes autosomal dominant familial cerebral cavernous malformations and disrupts cardiovascular development. The biological function of KRIT1 requires that its FERM (band 4.1, ezrin, radixin, moesin) domain physically interact with both the small GTPase Rap1 and the cytoplasmic tail of the Heart of glass (HEG1) membrane anchor. In this study, we show that the KRIT1 FERM domain can bind both Rap1 and HEG1 simultaneously, and we solved the crystal structure of the KRIT1-Rap1-HEG1 ternary complex. Rap1 binds on the surface of the F1 and F2 subdomains, in an interaction that leaves its Switch II region accessible to other potential effectors. HEG1 binds in a hydrophobic pocket at the KRIT1 F1 and F3 interface, and there is no overlap with the Rap1-binding site. Indeed, the affinity of KRIT1 or the KRIT1-Rap1 complex for HEG1 is comparable (Kd = 1.2 and 0.96 μm, respectively) showing that there is no competition between the two sites. Furthermore, analysis of this structure revealed a specific ionic interaction between the F2 lobe of KRIT1 and Rap1 that could explain the remarkable Rap1 specificity of KRIT1. This structural insight enabled design of KRIT1(K570I), a mutant that binds Rap1 with 8-fold lower affinity and exhibits increased binding to HRas. These data show that HEG1 can recruit the Rap1-KRIT complex to the plasma membrane where Rap1's Switch II region remains accessible and reveals an important determinant of KRIT1's specificity for Rap1.