Structure of eukaryotic purine/H(+) symporter UapA suggests a role for homodimerization in transport activity.

ABSTRACT: The uric acid/xanthine H(+) symporter, UapA, is a high-affinity purine transporter from the filamentous fungus Aspergillus nidulans. Here we present the crystal structure of a genetically stabilized version of UapA (UapA-G411VΔ1-11) in complex with xanthine. UapA is formed from two domains, a core domain and a gate domain, similar to the previously solved uracil transporter UraA, which belongs to the same family. The structure shows UapA in an inward-facing conformation with xanthine bound to residues in the core domain. Unlike UraA, which was observed to be a monomer, UapA forms a dimer in the crystals with dimer interactions formed exclusively through the gate domain. Analysis of dominant negative mutants is consistent with dimerization playing a key role in transport. We postulate that

SUBMITTER: Alguel Y 

PROVIDER: S-EPMC4837479 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature