Affordable Access

deepdyve-link
Publisher Website

The solution structure of the transducin-α-uncoordinated 119 protein complex suggests occlusion of the Gβ₁γ₁-binding sites.

Authors
  • Cheguru, Pallavi
  • Majumder, Anurima
  • Yadav, Ravi
  • Gopalakrishna, Kota N
  • Lokesh Gakhar
  • Artemyev, Nikolai O
Type
Published Article
Journal
FEBS Journal
Publisher
Wiley (Blackwell Publishing)
Publication Date
Feb 01, 2015
Volume
282
Issue
3
Pages
550–561
Identifiers
DOI: 10.1111/febs.13161
PMID: 25425538
Source
Medline
Keywords
License
Unknown

Abstract

Uncoordinated 119 protein (UNC119) is a partner of transducin-α subunit (Gαt ) that is essential for transducin trafficking in rod photoreceptors. The interaction is known to involve binding of the acylated N terminus of Gαt to the hydrophobic pocket of UNC119. To gain insights into the mechanism of transducin trafficking, we isolated a highly pure protein complex between myristoylated chimeric Gαt (Gαt *) and UNC119₅₀₋₂₄₀, and examined the solution structure by small angle X-ray scattering and chemical crosslinking. The solution structure of the Gαt -UNC119₅₀₋₂₄₀ complex was derived with rigid body/ab initio modeling against the small angle X-ray scattering data by use of known atomic structures of Gαt and UNC119, and a distance constraint based on the protein crosslinking with p-phenyldimaleimide. The model of the Gαt -UNC119₅₀₋₂₄₀ complex indicates rotation and bending of the N-terminal α-helix of Gαt from its position in the structure of the heterotrimeric G-protein transducin (Gt ). This allows a considerably more compact complex conformation, which also suggests a novel interface involving the switch II/α3-β5 surface of Gαt . Supporting a novel interface, UNC119 was found to bind full-length Gαt * more strongly than the Gαt N-terminal peptide. Furthermore, UNC119 competed with the effector molecule phosphodiesterase-6 γ-subunit, which is known to bind to the same surface of Gαt . The solution structure of the Gαt -UNC119 complex suggests that the ability of UNC119 to dissociate Gt subunits and release Gαt from the membrane is attributable to disruption and sterical occlusion of the Gβ₁γ₁-binding sites on Gαt .

Report this publication

Statistics

Seen <100 times