title: Involvement of histidine-rich domain of ZIP family transporter TjZNT1 in metal ion specificity.
abstract: The Zrt/Irt-like protein (ZIP) family generally contributes to metal homeostasis by regulating cation transport into the cytoplasm. Most ZIP members have a long variable loop between transmembrane domains III and IV, and these loops are predicted to be located in the cytoplasm. The loops contain a histidine-rich domain (HRD) postulated to serve as a metal ion binding site; however, its role has not yet been determined. We previously determined that deletion of the HRD did not affect the Ni tolerance ability of TjZNT1-a ZIP transporter that confers high Ni tolerance to yeast. In this study, we investigated the effect of HRD deletion on the ion transport ability of TjZNT1. The deletion of HRD increased the specificity for Zn2+, but not for Cd2+. In addition, we confirmed subcellular localizations of TjZNT1 and HRD-deleted mutants by green fluorescence protein (GFP)-fused proteins, indicating that the deletion of HRD did not affect the localization of TjZNT1. From these results, we propose that the HRD could be involved in the ion specificity of TjZNT1.
authors.affiliation: Faculty of Bioresources, Graduate School of Bioresources, Mie University, Kurimamachiya-cho 1577, Tsu, Mie 514-8507, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Nishida
authors.forename: Takafumi
authors.initials: T
authors.lastname: Mizuno
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Obata
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008670:Metals / Q000378:metabolism*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; D026901:Membrane Transport Proteins; D008670:Metals; D011993:Recombinant Fusion Proteins; D002104:Cadmium; D049452:Green Fluorescent Proteins; D015032:Zinc