Details

Autor(en) / Beteiligte

• Suzuki, Nobuchika
• Tsumoto, Kouhei
• Hajicek, Nicole
• Daigo, Kenji
• Tokita, Reiko
• Minami, Shiro
• Kodama, Tatsuhiko
• Hamakubo, Takao
• Kozasa, Tohru

Titel

Activation of Leukemia-associated RhoGEF by Gα13 with Significant Conformational Rearrangements in the InterfaceS

Ist Teil von

• The Journal of biological chemistry, 2009-02, Vol.284 (8), p.5000-5009

Ort / Verlag

American Society for Biochemistry and Molecular Biology

Erscheinungsjahr

2009

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The transient protein-protein interactions induced by guanine nucleotide-dependent conformational changes of G proteins play central roles in G protein-coupled receptor-mediated signaling systems. Leukemia-associated RhoGEF (LARG), a guanine nucleotide exchange factor for Rho, contains an RGS homology (RH) domain and Dbl homology/pleckstrin homology (DH/PH) domains and acts both as a GTPase-activating protein (GAP) and an effector for Gα 13 . However, the molecular mechanism of LARG activation upon Gα 13 binding is not yet well understood. In this study, we analyzed the Gα 13 -LARG interaction using cellular and biochemical methods, including a surface plasmon resonance (SPR) analysis. The results obtained using various LARG fragments demonstrated that active Gα 13 interacts with LARG through the RH domain, DH/PH domains, and C-terminal region. However, an alanine substitution at the RH domain contact position in Gα 13 resulted in a large decrease in affinity. Thermodynamic analysis revealed that binding of Gα 13 proceeds with a large negative heat capacity change (Δ C p°), accompanied by a positive entropy change (Δ S °). These results likely indicate that the binding of Gα 13 with the RH domain triggers conformational rearrangements between Gα 13 and LARG burying an exposed hydrophobic surface to create a large complementary interface, which facilitates complex formation through both GAP and effector interfaces, and activates the RhoGEF. We propose that LARG activation is regulated by an induced-fit mechanism through the GAP interface of Gα 13 .