The crystal structure of the RhoA-AKAP-Lbc DH-PH domain complex.

Abstract

The RhoGEF (Rho GTPase guanine-nucleotide-exchange factor) domain of AKAP-Lbc (A-kinase-anchoring protein-Lbc, also known as AKAP13) catalyses nucleotide exchange on RhoA and is involved in the development of cardiac hypertrophy. The RhoGEF activity of AKAP-Lbc has also been implicated in cancer. We have determined the X-ray crystal structure of the complex between RhoA-GDP and the AKAP-Lbc RhoGEF [DH (Dbl-homologous)-PH (pleckstrin homology)] domain to 2.1 Å (1 Å = 0.1 nm) resolution. The structure reveals important differences compared with related RhoGEF proteins such as leukaemia-associated RhoGEF. Nucleotide-exchange assays comparing the activity of the DH-PH domain to the DH domain alone showed no role for the PH domain in nucleotide exchange, which is explained by the RhoA-AKAP-Lbc structure. Comparison with a structure of the isolated AKAP-Lbc DH domain revealed a change in conformation of the N-terminal 'GEF switch' region upon binding to RhoA. Isothermal titration calorimetry showed that AKAP-Lbc has only micromolar affinity for RhoA, which combined with the presence of potential binding pockets for small molecules on AKAP-Lbc, raises the possibility of targeting AKAP-Lbc with GEF inhibitors.

• Authors: Kamal R Abdul Azeez, Stefan Knapp, João M P Fernandes, Enno Klussmann, Jonathan M Elkins
• Journal: The Biochemical journal (Biochem J) Vol. 464 Issue 2 Pg. 231-9 (Dec 01 2014) ISSN: 1470-8728 [Electronic] England
• PMID: 25186459 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• A Kinase Anchor Proteins
• AKAP13 protein, human
• Minor Histocompatibility Antigens
• Proto-Oncogene Proteins
• Rho Guanine Nucleotide Exchange Factors
• GTP Phosphohydrolases
• rhoA GTP-Binding Protein

Topics

• A Kinase Anchor Proteins (chemistry)
• Binding Sites
• Crystallography, X-Ray
• GTP Phosphohydrolases (chemistry)
• Humans
• Minor Histocompatibility Antigens
• Protein Conformation
• Protein Structure, Tertiary
• Proto-Oncogene Proteins (chemistry)
• Rho Guanine Nucleotide Exchange Factors (chemistry)
• rhoA GTP-Binding Protein (chemistry)