title: The extracellular loop of IRT1 ZIP protein--the chosen one for zinc?
abstract: Zinc complexes with the extracellular loop of IRT1 (iron-regulated transporter 1), a ZIP (ZRT/IRT - Related Protein) family protein from Arabidopsis thaliana, have been studied. This unstructured fragment is responsible for metal selectivity and is located between the II and III transmembrane domains of IRT1. Zinc complexes with the Ac-(95)MHVLPDSFEMLSSICLEENPWHK(117)-NH2 peptide (IRT1), revealed surprisingly high thermodynamic stability. Additionally, an N-terminal fragment of human/mouse ZIP 13 zinc transporter (MPGCPCPGCGMACPR-NH2, later called ZIP13+C), has been chosen for the thermodynamic stability comparison studies. The relative ZIP13+C stability has been shown using several Zn(2+) complexes with artificially arranged multi-cysteine sequences. An interesting coordination mode has been proposed for the IRT1-Zn(2+) complex, in which imidazoles from two histidines (His-96 and His-116), a cysteine thiolate (Cys-109) and one of a glutamic acid carboxyl group are involved. All data were collected using potentiometric, NMR and mass spectrometric methods.
authors.affiliation: Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland. Electronic address: slawomir.potocki@chem.uni.wroc.pl.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Potocki
authors.forename: Daniela
authors.initials: D
authors.lastname: Valensin
authors.forename: Francesca
authors.initials: F
authors.lastname: Camponeschi
authors.forename: Henryk
authors.initials: H
authors.lastname: Kozlowski
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000737:chemistry*; D027682:Cation Transport Proteins / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010455:Peptides / Q000235:genetics; D021241:Spectrometry, Mass, Electrospray Ionization; D015032:Zinc / Q000737:chemistry*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D056831:Coordination Complexes; C099651:IRT1 protein, Arabidopsis; D008024:Ligands; D010455:Peptides; C498424:SLC39A2 protein, human; D015032:Zinc
keywords: IRT1 protein; Thermodynamic stability; ZIP transporters; Zinc complexes