Ric-8A, a G protein chaperone with nucleotide exchange activity induces long-range secondary structure changes in Gα.
Elife
; 52016 12 23.
Article
en En
| MEDLINE
| ID: mdl-28008853
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.
Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Proteínas Nucleares
/
Proteínas ras
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Chaperonas Moleculares
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Factores de Intercambio de Guanina Nucleótido
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Subunidades alfa de la Proteína de Unión al GTP
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Elife
Año:
2016
Tipo del documento:
Article
País de afiliación:
Estados Unidos