One motif to bind them: A small-XXX-small motif affects transmembrane domain 1 oligomerization, function, localization, and cross-talk between two yeast GPCRs

Antonia Lock, Rachel Forfar, Cathryn Weston, Leo Bowsher, Graham J.G. Uptond, Christopher A. Reynolds, Graham Ladds, Ann M. Dixon

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

G protein-coupled receptors (GPCRs) are the largest family of cell-surface receptors in mammals and facilitate a range of physiological responses triggered by a variety of ligands. GPCRs were thought to function as monomers, however it is now accepted that GPCR homo- and hetero-oligomers also exist and influence receptor properties. The Schizosaccharomyces pombe GPCR Mam2 is a pheromone-sensing receptor involved in mating and has previously been shown to form oligomers in vivo. The first transmembrane domain (TMD) of Mam2 contains a small-XXX-small motif, overrepresented in membrane proteins andwell-known for promoting helix-helix interactions. An ortholog of Mam2 in Saccharomyces cerevisiae, Ste2, contains an analogous small-XXX-small motif which has been shown to contribute to receptor homo-oligomerization, localization and function. Here we have used experimental and computational techniques to characterize the role of the small-XXX-small motif in function and assembly of Mam2 for the first time. We find that disruption of the motif via mutagenesis leads to reduction of Mam2 TMD1 homo-oligomerization and pheromone-responsive cellular signaling of the fulllength protein. It also impairs correct targeting to the plasma membrane. Mutation of the analogous motif in Ste2 yielded similar results, suggesting a conservedmechanismfor assembly. Using co-expression of the two fungal receptors in conjunction with computational models, we demonstrate a functional change in G protein specificity and propose that this is brought about through hetero-dimeric interactions of Mam2 with Ste2 via the complementary small-XXX-small motifs. This highlights the potential of these motifs to affect a range of properties that can be investigated in other GPCRs.

Original languageEnglish
Pages (from-to)3036-3051
Number of pages16
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1838
Issue number12
Early online date23 Aug 2014
DOIs
Publication statusPublished - Dec 2014
Externally publishedYes

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Keywords

  • Cross-talk
  • GPCR
  • Oligomerization
  • Signaling
  • TOXCAT
  • Trafficking

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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