Cryo-EM study of the human sulfate anion transporter 1, hSAT1

Abstract

Solute carrier 26A gene family encode various types of anion transporters and channels transporting diverse anions. The mammal SLC26A gene family are composed of 11genes, SLC26A1-A11. Each gene generally has 10-14 hydrophobic transmembrane domain and C- terminal cytoplasmic sulfate transporter and anti-sigma factor antagonist (STAS) domain. Among the SLC26A family, SLC26A1 that encodes hSAT1 is anion exchanger. The SAT1 is known to mediate the exchange of SO42-/ SO42-, SO42-/ Cl-, SO42-/oxalate, SO42-/OH- and Cl-/ Cl-. Some results indicate that extracellular pH and concentration of Cl- regulate transport mediated by SAT1. Although mechanism is not investigated, these regulations are assumed that extracellular regulations will be mediated by allosteric regulation. In human, there is no result that hSAT1 is related to human disease yet. In mice, mSat1 is related to hyperoxaluria, urolithiasis, kidney stone, and enamel maturation. Since hSAT1 and mSat1 have high sequence homology (78% amino acid identity) and two proteins are a high level of expression in the kidney, hSAT1 is assumed that involved in kidney stone diseases. In this study, we purified hSAT1 with DDM/CHS and using the nanodisc method. Using hSAT1 that purified with DDM/CHS, Cryo-grid was prepared. Then, we collect movie data using Cryo-EM. After processing, we confirmed the rough 3D initial model of hSAT1. If the structure of hSAT1 is solved, it will be useful in the development of drugs for kidney stone diseases.