Efficient expression and immunoaffinity purification of human trace amine-associated receptor 5 from E. coli cell-free system

Protein Pept Lett. 2013 Apr;20(4):473-80.

Abstract

G protein-coupled receptors (GPCRs) represent attractive targets for bioactive and drug discovery programs. The availability of purified receptors in milligram quantities is essential to spur the advancement of protein-based analyses in these programs, although it is still a challenging goal to achieve. Here we report the production of a bioengineered GPCR of human trace amine-associated receptor 5 (hTAAR5) from an E. coli cell-free system. Both the hTAAR5 and hTAAR5-T4 lysozyme fusion proteins (hTAAR5-T4L) were cloned and expressed in this process, with the latter designed for further protein crystallization trials. The detergent Brij-35 was found to solubilize the produced hTAAR5 and hTAAR5-T4L effectively. Immunoaffinity purification in combination with gel filtration was employed to purify the receptors to high homogeneity. The final yields of monomeric hTAAR5 and hTAAR5-T4L from a 1 mL cell-free reaction were 0.4 mg and 0.5 mg, respectively. Circular Dichroism (CD) spectroscopy indicated that both hTAAR5 and hTAAR5- T4L were correctly folded after purification, with characteristic high α-helical contents ( > 45%).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell-Free System
  • Chromatography, Gel
  • Circular Dichroism
  • Detergents / chemistry
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Humans
  • Molecular Sequence Data
  • Muramidase / genetics
  • Muramidase / metabolism
  • Polyethylene Glycols / chemistry
  • Protein Engineering / methods*
  • Protein Folding
  • Protein Structure, Secondary
  • Receptors, G-Protein-Coupled / genetics*
  • Receptors, G-Protein-Coupled / isolation & purification*
  • Receptors, G-Protein-Coupled / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / isolation & purification*
  • Recombinant Fusion Proteins / metabolism*

Substances

  • Detergents
  • Receptors, G-Protein-Coupled
  • Recombinant Fusion Proteins
  • TAAR5 protein, human
  • Polyethylene Glycols
  • Muramidase
  • Brij 35