Charakterisierung von CDF-Transportern aus Saccharomyces cerevisiae, Schizosaccharomyces pombe und Arabidopsis thaliana [article]

Tanja Bloß, Martin-Luther Universität, Universitäts- Und Landesbibliothek Sachsen-Anhalt
Metal tolerance and homeostasis in plants is reached by controlled transport processes in connection with sequestration by specific metal-binding components like phytochelatins, metallo-chaperones and metallothioneins. Cation diffusion facilitators are a family of metal transport proteins which have been found in a variety of organisms. The first examples were the CzcD protein from the Gram-negative bacterium Ralstonia metallidurans strain CH34 and Zrc1p from the yeast Saccharomyces cerevisiae.
more » ... romyces cerevisiae. Both proteins are transporters also involved in regulation of metal ion homeostasis. The Zat1p zinc transporter from Arabidopsis thaliana is the first CDF protein from plants. When heterologously expressed in Escherichia coli, Zat1p bound zinc in a metal blot and formed dimers only present in the membrane. Binding of zinc occured mainly to a hydrophilic amino acid stretch from H182 to H232. A Zat1p/Zat1p*Δ(M1-I25) mixture of the protein 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 cadmium only at 1% of the zinc transport rate. Zat1p functioned as uptake system for 65Zn2+ 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 Δzrc1 single or of a Δzrc1Δcot1 double mutant strain of Saccharomyces cerevisiae.
doi:10.25673/2936 fatcat:gh5kz6y2sjhmvmlkvwmg62nji4