Document Type
Article
Publication Title
eLife
Publication Date
12-23-2016
Volume
5
Disciplines
Biology | Life Sciences
Abstract
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.
Keywords
biochemistry, biophysics, heterotrimeric G proteins, hydrogen-deuterium exchange mass spectrometry, non-receptor guanine nucleotide exchange factor, protein dynamics, protein secondary structure, rat, structural biology
DOI
10.7554/eLife.19238
Rights
© 2016 Kant et al.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Kant, Ravi; Zeng, Baisen; Thomas, Celestine J.; Bothner, Brian; and Sprang, Stephen R., "Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα" (2016). Biological Sciences Faculty Publications. 481.
https://scholarworks.umt.edu/biosci_pubs/481