Bacterial over-production of the functionally active human SLC38A2 (SNAT2) exploiting the mistic tag: a cheap and fast tool for testing ligands

Mol Biol Rep. 2024 Feb 23;51(1):336. doi: 10.1007/s11033-023-08976-3.

Abstract

Background: SLC38A2 is a ubiquitously expressed Na+-dependent transporter specific for small and medium neutral amino acids. It is involved in human pathologies, such as type II diabetes and cancer. Despite its relevance in human physio-pathology, structure/function relationship studies and identification of ligands with regulatory roles are still in infancy.

Methods and results: The cDNA coding for SLC38A2 was cloned in the pET-28-Mistic vector, and the BL21 codon plus RIL strain was transformed with the recombinant construct. 0.5% glucose and oxygen availability were crucial for protein expression. The over-expressed hSNAT2-Mistic chimera was cleaved on column and purified by nickel-chelating affinity chromatography, with a yield of about 60 mg/Liter cell culture. The purified hSNAT2 was reconstituted in proteoliposomes in an active form with a right-side-out orientation with respect to the native membrane.

Conclusions: The addition of a Mistic tag at the N-terminus of the SNAT2 protein was crucial for its over-expression and purification. The purified protein was functionally active, representing a powerful tool for performing structure/function studies and testing ligands as inhibitors and/or activators.

Keywords: Proteoliposomes; Purification; Refolding; SLC; SNAT2.

MeSH terms

  • Amino Acid Transport System A* / biosynthesis
  • Humans
  • Membrane Transport Proteins

Substances

  • Amino Acid Transport System A
  • Membrane Transport Proteins
  • SLC38A2 protein, human