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Merck
  • Crystal structures of a ZIP zinc transporter reveal a binuclear metal center in the transport pathway.

Crystal structures of a ZIP zinc transporter reveal a binuclear metal center in the transport pathway.

Science advances (2017-09-07)
Tuo Zhang, Jian Liu, Matthias Fellner, Chi Zhang, Dexin Sui, Jian Hu
초록

Zrt/Irt-like proteins (ZIPs) play fundamental roles in metal metabolism/homeostasis and are broadly involved in numerous physiological and pathological processes. The lack of high-resolution structure of the ZIPs hinders understanding of the metal transport mechanism. We report two crystal structures of a prokaryotic ZIP in lipidic cubic phase with bound metal substrates (Cd2+ at 2.7 Å and Zn2+ at 2.4 Å). The structures revealed a novel 3+2+3TM architecture and an inward-open conformation occluded at the extracellular side. Two metal ions were trapped halfway through the membrane, unexpectedly forming a binuclear metal center. The Zn2+-substituted structure suggested asymmetric functions of the two metal-binding sites and also revealed a route for zinc release. Mapping of disease-causing mutations, structure-guided mutagenesis, and cell-based zinc transport assay demonstrated the crucial role of the binuclear metal center for human ZIP4. A metal transport mechanism for the ZIP from Bordetella bronchiseptica was proposed, which is likely applicable to other ZIPs.

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Sigma-Aldrich
1-Oleoyl-rac-glycerol, ≥99%