Crystallization scale preparation of a stable GPCR signaling complex between constitutively active rhodopsin and G-protein

PLoS One. 2014 Jun 30;9(6):e98714. doi: 10.1371/journal.pone.0098714. eCollection 2014.

Abstract

The activation of the G-protein transducin (Gt) by rhodopsin (Rho) has been intensively studied for several decades. It is the best understood example of GPCR activation mechanism and serves as a template for other GPCRs. The structure of the Rho/G protein complex, which is transiently formed during the signaling reaction, is of particular interest. It can help understanding the molecular details of how retinal isomerization leads to the G protein activation, as well as shed some light on how GPCR recognizes its cognate G protein. The native Rho/Gt complex isolated from bovine retina suffers from low stability and loss of the retinal ligand. Recently, we reported that constitutively active mutant of rhodopsin E113Q forms a Rho/Gt complex that is stable in detergent solution. Here, we introduce methods for a large scale preparation of the complex formed by the thermo-stabilized and constitutively active rhodopsin mutant N2C/M257Y/D282C(RhoM257Y) and the native Gt purified from bovine retinas. We demonstrate that the light-activated rhodopsin in this complex contains a covalently bound unprotonated retinal and therefore corresponds to the active metarhodopin II state; that the isolated complex is active and dissociates upon addition of GTPγS; and that the stoichiometry corresponds to a 1∶1 molar ratio of rhodopsin to the heterotrimeric G-protein. And finally, we show that the rhodopsin also forms stable complex with Gi. This complex has significantly higher thermostability than RhoM257Y/Gt complex and is resistant to a variety of detergents. Overall, our data suggest that the RhoM257Y/Gi complex is an ideal target for future structural and mechanistic studies of signaling in the visual system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • HEK293 Cells
  • Humans
  • Mutation, Missense
  • Protein Binding
  • Protein Stability
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism
  • Rhodopsin / chemistry
  • Rhodopsin / genetics
  • Rhodopsin / metabolism*
  • Transducin / chemistry
  • Transducin / metabolism*

Substances

  • Protein Subunits
  • Rhodopsin
  • Transducin

Grants and funding

SM is supported by the Roche postdoctoral fellowship (RPF113, www.roche.com). This work was supported by the Swiss National Science Foundation (www.snf.ch) grants 133810 (DBV, JS, GFXS), 135754 (DBV), 141898 (DBV, GFXS), 132815 (GFXS, JS), 141235 (JS) and NCCR Structural Biology (GFXS). Roche provided funding in the form of salaries for the employees and co-authors (MF, GS, MH and RJPD). The Swiss National Science Foundation had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.