Characterization of the ZAT1p zinc transporter from Arabidopsis thaliana in microbial model organisms and reconstituted proteoliposomes
2002
Bloss, T. | Clemens, S. | Nies, D.H.
The ZAT1p zinc transporter from Arabidopsis thaliana (L.) Heynh. is a member of the cation diffusion facilitator (CDF) protein family. When heterologously expressed in Escherichia coli, ZAT1p bound zinc in a metal blot. Binding of zinc occurred mainly to the hydrophilic amino acid region from H182 to H232. A ZAT1p/ZAT1p*delta(M1-I25) protein mixture was purified and reconstituted into proteoliposomes. Uptake of zinc into the proteoliposomes did not require a proton gradient across the liposomal membrane. ZAT1p did not transport cobalt, and transported cadmium at only 1% of the zinc transport rate. ZAT1p functioned as an uptake system for 65Zn(2+) in two strains of the Gram-negative bacterium Ralstonia metallidurans, which were different in their content of zinc-efflux systems. The ZAT1 gene did not rescue increased zinc sensitivity of a deltaZRC1 single-mutant strain or of a deltaZRC1 deltaCOT1 double-mutant strain of Saccharomyces cerevisiae, but ZAT1 complemented this phenotype in a deltaSpZRC1 mutant strain of Schizosaccharomyces pombe.
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