1vfi | pdb_00001vfi
Solution Structure of Vanabin2 (RUH-017), a Vanadium-binding Protein from Ascidia sydneiensis samea
Structural highlights
FunctionVBP2_ASCSS Acts as a vanadium reductase which may form an electron transfer cascade in conjunction with NADPH and glutathione through thiol disulfide exchange reactions. Partial cleavage of its disulfide bonds results in the reduction of V(5+) to V(4+). Binds up to 24 V(4+) ions per protein at pH 7.5. Also binds Fe(3+) and Cu(2+) and, to a lesser extent, Co(2+), Zn(2+) and Ni(2+).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedAscidians belonging to the suborder Phlebobranchia are known to accumulate high levels of a transition metal, vanadium, in their blood cells, called vanadocytes, although the mechanism for this biological phenomenon remains unclear. Recently, we identified vanadium(IV)-binding proteins, designated as Vanabins, from vanadium-accumulating ascidians. Here, we report the first 3D structure of Vanabin2 from an ascidian, Ascidia sydneiensis samea, in an aqueous solution. The structure revealed a novel bow-shaped conformation, with four alpha-helices connected by nine disulfide bonds. There are no structural homologues reported so far. The 15N heteronuclear single-quantum coherence (HSQC) perturbation experiments of Vanabin2 indicated that vanadyl cations, which are exclusively localized on the same face of the molecule, are coordinated by amine nitrogens derived from amino acid residues such as lysines, arginines, and histidines, as suggested by the electron paramagnetic resonance (EPR) results. The present NMR studies provide information that will contribute toward elucidating the mechanism of vanadium accumulation in ascidians. Solution structure of Vanabin2, a vanadium(IV)-binding protein from the vanadium-rich ascidian Ascidia sydneiensis samea.,Hamada T, Asanuma M, Ueki T, Hayashi F, Kobayashi N, Yokoyama S, Michibata H, Hirota H J Am Chem Soc. 2005 Mar 30;127(12):4216-22. PMID:15783203[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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