Genes and proteins involved in vanadium accumulation by ascidians

Hitoshi Michibata, Masafumi Yoshinaga, Masao Yoshihara, Norifumi Kawakami, Nobuo Yamaguchi, Tatsuya Ueki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Citations (Scopus)

Abstract

About a hundred years ago, Henze discovered high levels of vanadium in the blood (coelomic) cells of an ascidian collected from the Bay of Naples. The intracellular vanadium concentration of some species in the family Ascidiidae can be as high as 350 mM, which is 107 times the concentration in seawater. Vanadium ions, thought to be present in the +5 oxidation state in seawater, are reduced to the +3 oxidation state via the +4 oxidation state and are stored in the vacuole of vanadocytes, the vanadium-containing cells, where high levels of protons and sulfate are also contained. To investigate this unusual phenomenon, we have isolated many proteins and genes that might be involved in the accumulation and reduction of vanadium. To date, more than five types of vanadium-binding protein, designated as Vanabin family, have been isolated from vanadocytes. In addition, four types of enzyme related to the pentose phosphate pathway that produces NADPH were revealed to be located in vanadocytes, and NADPH produced by the pentose phosphate pathway participates in the reduction of vanadium(V) to vanadium(IV). Vacuolar-type H +-ATPase (V-ATPase) maintains the low pH in the vacuole and is thought to provide the energy for vanadium accumulation. Using an immobilized metal-affinity chromatography (IMAC) and gene homology cloning, we have further obtained a Vanabin homologue in blood plasma, metalATPase, glutathione-S- transferase and SO4-2 transporter. Now, it becomes important to elucidate not only physiological roles of these proteins but also to resolve how these proteins share their roles to accumulate vanadium in ascidians.

Original languageEnglish
Title of host publicationVanadium
Subtitle of host publicationThe Versatile Metal
EditorsKenneth Kustin, Joao Pessoa, Debbie Crans
Pages264-280
Number of pages17
Publication statusPublished - 2007 Dec 11
Externally publishedYes

Publication series

NameACS Symposium Series
Volume974
ISSN (Print)0097-6156

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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  • Cite this

    Michibata, H., Yoshinaga, M., Yoshihara, M., Kawakami, N., Yamaguchi, N., & Ueki, T. (2007). Genes and proteins involved in vanadium accumulation by ascidians. In K. Kustin, J. Pessoa, & D. Crans (Eds.), Vanadium: The Versatile Metal (pp. 264-280). (ACS Symposium Series; Vol. 974).