Directed evolution of a G protein-coupled receptor for expression, stability, and binding selectivity

Casim A. Sarkar, Igor Dodevski, Manca Kenig, Stefan Dudli, Anja Mohr, Emmanuel Hermans, Andreas Plückthun

Research output: Contribution to journalArticlepeer-review

131 Scopus citations

Abstract

We outline a powerful method for the directed evolution of integral membrane proteins in the inner membrane of Escherichia coli. For a mammalian G protein-coupled receptor, we arrived at a sequence with an order-of-magnitude increase in functional expression that still retains the biochemical properties of wild type. This mutant also shows enhanced heterologous expression in eukaryotes (12-fold in Pichia pastoris and 3-fold in HEK293T cells) and greater stability when solubilized and purified, indicating that the biophysical properties of the protein had been under the pressure of selection. These improvements arise from multiple small contributions, which would be difficult to assemble by rational design. In a second screen, we rapidly pinpointed a single amino acid substitution in wild type that abolishes antagonist binding while retaining agonist-binding affinity. These approaches may alleviate existing bottlenecks in structural studies of these targets by providing sufficient quantities of stable variants in defined conformational states.

Original languageEnglish (US)
Pages (from-to)14808-14813
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number39
DOIs
StatePublished - Sep 30 2008

Keywords

  • Integral membrane proteins
  • Protein engineering
  • Protein folding

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