title: Existence of a tungsten-binding protein in Acidithiobacillus ferrooxidans AP19-3.
abstract: A tungsten-binding protein was purified from a plasma membrane preparation of the iron-oxidizing bacterium, Acidithiobacillus ferrooxidans AP19-3 in an electrophoretically homogenous state. The protein was composed of two subunits with apparent molecular masses of 12 and 20.7 kDa. The molecular mass of the native protein was estimated to be 26.4 kDa in the presence of 1.5% 1-o-octyl-D -glucopyranoside (OGL), indicating that the native tungsten-binding protein is a heterodimeric protein. The amounts of tungsten bound to 1 mg of plasma membranes of A. ferrooxidans AP19-3 and the purified tungsten-binding protein at pH 3.0 were 191 and 1506 mug, respectively. In contrast, the amounts of tungsten bound to 1 mg of albumin, aldolase, catalase, chymotrypsinogen A, ferritin, and ferredoxin at pH 3.0 were 13.1, 18.6, 12.8, 16.6, 11.4, and 6.1 mug, respectively. Incubation of the tungsten-binding protein for 1 h with 10 mM Na(2)WO(4) plus 10 mM metal ion, such as NaVO(3), Na(2)MoO(4), CuSO(4), NiSO(4), MnSO(4), CoSO(4), or CdCl(2), did not markedly affect the amount of tungsten bound to the tungsten-binding protein, suggesting that the protein specifically binds tungsten.
authors.affiliation: Division of Science and Technology for Energy Conversion, Graduate School of Natural Science and Technology, Okayama University, Tsushima Naka, Okayama 700-8530, Japan. sugio@cc.okayama-u.ac.jp
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sugio
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kuwano
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hamago
authors.forename: Atsunori
authors.initials: A
authors.lastname: Negishi
authors.forename: Terunobu
authors.initials: T
authors.lastname: Maeda
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Takeuchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kamimura