Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα

eLife

Baisen Zeng¹  Stephen R Sprang¹  Celestine J Thomas¹  Brian Bothner²  Ravi Kant² 

[1] Center for Biomolecular Structure and Dynamics, The University of Montana, Missoula, United States;Department of Chemistry and Biochemistry, Montana State University, Bozeman, United States;

关键词: heterotrimeric G proteins;    non-receptor guanine nucleotide exchange factor;    hydrogen-deuterium exchange mass spectrometry;    protein secondary structure;    protein dynamics;   

DOI  :  10.7554/eLife.19238

来源: DOAJ

【 摘 要 】

Cytosolic Ric-8A has guanine nucleotide exchange factor (GEF) activity and is a chaperone for several classes of heterotrimeric G protein α subunits in vertebrates. Using Hydrogen-Deuterium Exchange-Mass Spectrometry (HDX-MS) we show that Ric-8A disrupts the secondary structure of the Gα Ras-like domain that girds the guanine nucleotide-binding site, and destabilizes the interface between the Gαi1 Ras and helical domains, allowing domain separation and nucleotide release. These changes are largely reversed upon binding GTP and dissociation of Ric-8A. HDX-MS identifies a potential Gα interaction site in Ric-8A. Alanine scanning reveals residues crucial for GEF activity within that sequence. HDX confirms that, like G protein-coupled receptors (GPCRs), Ric-8A binds the C-terminus of Gα. In contrast to GPCRs, Ric-8A interacts with Switches I and II of Gα and possibly at the Gα domain interface. These extensive interactions provide both allosteric and direct catalysis of GDP unbinding and release and GTP binding.

【 授权许可】

Unknown