Baisen Zeng, Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, USA.
Tung-Chung Mou, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA; Division of Biological Sciences, 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 94309, USA.
Andrea Steiner, Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.
Wenxi Yu, Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Makaia Papasergi-Scott, Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA.
Gregory G. Tall, Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Franz Hagn, Bavarian NMR Center at the Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.
Stephen R. Sprang, Graduate Program in Biochemistry and Biophysics, University of Montana, Missoula, MT 59812, USA; Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT 59812, USA; Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA. Electronic address: stephen.sprang@umontana.edu.

Document Type

Article

Publication Title

Structure (London, England : 1993)

Publication Date

7-2-2019

Volume

27

Issue

7

Disciplines

Biology | Life Sciences

Abstract

Ric-8A is a 530-amino acid cytoplasmic molecular chaperone and guanine nucleotide exchange factor (GEF) for i, q, and 12/13 classes of heterortrimeric G protein alpha subunits (Gα). We report the 2.2-Å crystal structure of the Ric-8A Gα-binding domain with GEF activity, residues 1-452, and is phosphorylated at Ser435 and Thr440. Residues 1-429 adopt a superhelical fold comprised of Armadillo (ARM) and HEAT repeats, and the C terminus is disordered. One of the phosphorylated residues potentially binds to a basic cluster in an ARM motif. Amino acid sequence conservation and published hydrogen-deuterium exchange data indicate repeats 3 through 6 to be a putative Gα-binding surface. Normal mode modeling of small-angle X-ray scattering data indicates that phosphorylation induces relative rotation between repeats 1-4, 5-6, and 7-9. 2D H-N-TROSY spectra of [H,N]-labeled Gαi1 in the presence of R452 reveals chemical shift perturbations of the C terminus and Gαi1 residues involved in nucleotide binding.

Keywords

X-ray crystallography, guanine nucleotide exchange factor, heteronuclear nuclear magnetic resonance, heterotrimeric G protein, molecular chaperone, protein dynamics, protein structure, small-angle X-ray scattering

DOI

10.1016/j.str.2019.04.013

Rights

© 2019 Elsevier Ltd.

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