Production of functional human vitamin A transporter/RBP receptor (STRA6) for structure determination

PLoS One. 2015 Mar 27;10(3):e0122293. doi: 10.1371/journal.pone.0122293. eCollection 2015.

Abstract

STRA6 is a plasma membrane protein that mediates the transport of vitamin A, or retinol, from plasma retinol binding protein (RBP) into the cell. Mutations in human STRA6 are associated with Matthew-Wood syndrome, which is characterized by severe developmental defects. Despite the obvious importance of this protein to human health, little is known about its structure and mechanism of action. To overcome the difficulties frequently encountered with the production of membrane proteins for structural determination, STRA6 has been expressed in Pichia pastoris as a fusion to green fluorescent protein (GFP), a strategy which has been a critical first step in solving the crystal structures of several membrane proteins. STRA6-GFP was correctly targeted to the cell surface where it bound RBP. Here we report the large-scale expression, purification and characterisation of STRA6-GFP. One litre of culture, corresponding to 175 g cells, yielded about 1.5 mg of pure protein. The interaction between purified STRA6 and its ligand RBP was studied by surface plasmon resonance-based binding analysis. The interaction between STRA6 and RBP was not retinol-dependent and the binding data were consistent with a transient interaction of 1 mole RBP/mole STRA6.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Membrane Proteins / biosynthesis*
  • Membrane Proteins / genetics
  • Membrane Proteins / isolation & purification*
  • Pichia / genetics
  • Pichia / metabolism*
  • Protein Binding
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Retinol-Binding Proteins, Plasma / metabolism
  • Surface Plasmon Resonance

Substances

  • Membrane Proteins
  • Recombinant Fusion Proteins
  • Retinol-Binding Proteins, Plasma
  • STRA6 protein, human
  • Green Fluorescent Proteins

Grants and funding

This work was supported by Science Foundation Ireland (www.sfi.ie), grant number 08/IN.1/B1900. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.