Structure of the G protein chaperone and guanine nucleotide exchange factor Ric-8A bound to Gαi1

Authors

Levi J. McClelland, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
Kaiming Zhang, Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA.
Tung-Chung Mou, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
Jake Johnston, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
Cindee Yates-Hansen, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
Shanshan Li, Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA.
Celestine J. Thomas, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA.
Tzanko I. Doukov, Macromolecular Crystallography Group, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA, 94025, USA.
Sarah Triest, Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
Alexandre Wohlkonig, Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
Gregory G. Tall, Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
Jan Steyaert, Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
Wah Chiu, Department of Bioengineering and James H. Clark Center, Stanford University, Stanford, CA, 94305, USA. wahc@stanford.edu.
Stephen R. Sprang, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, 59812, USA. Stephen.sprang@umontana.edu.

Document Type

Article

Publication Title

Nature Communications

Publication Date

2-26-2020

Volume

11

Issue

1

Disciplines

Biology | Life Sciences

Abstract

Ric-8A is a cytosolic Guanine Nucleotide exchange Factor (GEF) that activates heterotrimeric G protein alpha subunits (Gα) and serves as an essential Gα chaperone. Mechanisms by which Ric-8A catalyzes these activities, which are stimulated by Casein Kinase II phosphorylation, are unknown. We report the structure of the nanobody-stabilized complex of nucleotide-free Gα bound to phosphorylated Ric-8A at near atomic resolution by cryo-electron microscopy and X-ray crystallography. The mechanism of Ric-8A GEF activity differs considerably from that employed by G protein-coupled receptors at the plasma membrane. Ric-8A engages a specific conformation of Gα at multiple interfaces to form a complex that is stabilized by phosphorylation within a Ric-8A segment that connects two Gα binding sites. The C-terminus of Gα is ejected from its beta sheet core, thereby dismantling the GDP binding site. Ric-8A binds to the exposed Gα beta sheet and switch II to stabilize the nucleotide-free state of Gα.

DOI

10.1038/s41467-020-14943-4

Rights

© The Author(s) 2020

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

McClelland, Levi J.; Zhang, Kaiming; Mou, Tung-Chung; Johnston, Jake; Yates-Hansen, Cindee; Li, Shanshan; Thomas, Celestine J.; Doukov, Tzanko I.; Triest, Sarah; Wohlkonig, Alexandre; Tall, Gregory G.; Steyaert, Jan; Chiu, Wah; and Sprang, Stephen R., "Structure of the G protein chaperone and guanine nucleotide exchange factor Ric-8A bound to Gαi1" (2020). Biological Sciences Faculty Publications. 476.
https://scholarworks.umt.edu/biosci_pubs/476