Crystal Structure of a Divalent Metal Ion Transporter CorA at 2.9 Angstrom Resolution

Abstract

CorA family members are ubiquitously distributed transporters of divalent metal cations and are considered to be the primary Mg²⁺ transporter of Bacteria and Archaea. We have determined a 2.9 angstrom resolution structure of CorA from Thermotoga maritima that reveals a pentameric cone–shaped protein. Two potential regulatory metal binding sites are found in the N-terminal domain that bind both Mg²⁺ and Co²⁺. The structure of CorA supports an efflux system involving dehydration and rehydration of divalent metal ions potentially mediated by a ring of conserved aspartate residues at the cytoplasmic entrance and a carbonyl funnel at the periplasmic side of the pore.