The extracellular loop of IRT1 ZIP protein ¡ª the chosen one for zinc?

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• 作者：Slawomir Potocki ; Daniela Valensin ; Francesca Camponeschi ; Henryk Kozlowski
• 关键词：IRT1 protein ; ZIP transporters ; Zinc complexes ; Thermodynamic stability
• 刊名：Journal of Inorganic Biochemistry
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：127
• 期：Complete
• 页码：246-252
• 全文大小：1018 K

文摘

Zinc complexes with the extracellular loop of IRT1 (iron-regulated transporter 1), a ZIP (ZRT/IRT ¡ª 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.