Detergent screening and purification of the human liver ABC transporters BSEP (ABCB11) and MDR3 (ABCB4) expressed in the yeast Pichia pastoris

PLoS One. 2013 Apr 4;8(4):e60620. doi: 10.1371/journal.pone.0060620. Print 2013.

Abstract

The human liver ATP-binding cassette (ABC) transporters bile salt export pump (BSEP/ABCB11) and the multidrug resistance protein 3 (MDR3/ABCB4) fulfill the translocation of bile salts and phosphatidylcholine across the apical membrane of hepatocytes. In concert with ABCG5/G8, these two transporters are responsible for the formation of bile and mutations within these transporters can lead to severe hereditary diseases. In this study, we report the heterologous overexpression and purification of human BSEP and MDR3 as well as the expression of the corresponding C-terminal GFP-fusion proteins in the yeast Pichia pastoris. Confocal laser scanning microscopy revealed that BSEP-GFP and MDR3-GFP are localized in the plasma membrane of P. pastoris. Furthermore, we demonstrate the first purification of human BSEP and MDR3 yielding ∼1 mg and ∼6 mg per 100 g of wet cell weight, respectively. By screening over 100 detergents using a dot blot technique, we found that only zwitterionic, lipid-like detergents such as Fos-cholines or Cyclofos were able to extract both transporters in sufficient amounts for subsequent functional analysis. For MDR3, fluorescence-detection size exclusion chromatography (FSEC) screens revealed that increasing the acyl chain length of Fos-Cholines improved monodispersity. BSEP purified in n-dodecyl-β-D-maltoside or Cymal-5 after solubilization with Fos-choline 16 from P. pastoris membranes showed binding to ATP-agarose. Furthermore, detergent-solubilized and purified MDR3 showed a substrate-inducible ATPase activity upon addition of phosphatidylcholine lipids. These results form the basis for further biochemical analysis of human BSEP and MDR3 to elucidate the function of these clinically relevant ABC transporters.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B / chemistry
  • ATP Binding Cassette Transporter, Subfamily B / genetics*
  • ATP Binding Cassette Transporter, Subfamily B / isolation & purification*
  • ATP Binding Cassette Transporter, Subfamily B / metabolism
  • ATP Binding Cassette Transporter, Subfamily B, Member 11
  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / genetics*
  • ATP-Binding Cassette Transporters / isolation & purification*
  • ATP-Binding Cassette Transporters / metabolism
  • Adenosine Triphosphatases / metabolism
  • Cloning, Molecular
  • Detergents / chemistry
  • Gene Expression*
  • Humans
  • Liver / metabolism*
  • Pichia / genetics*
  • Pichia / metabolism
  • Protein Transport
  • Solubility

Substances

  • ABCB11 protein, human
  • ATP Binding Cassette Transporter, Subfamily B
  • ATP Binding Cassette Transporter, Subfamily B, Member 11
  • ATP-Binding Cassette Transporters
  • Detergents
  • multidrug resistance protein 3
  • Adenosine Triphosphatases

Grants and funding

This work was supported by the Clinic Research Unit 217 (KFO 217) “Hepatobiliary transport and liver diseases" (project TP3 to L.S.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.