title: Detoxification of cadmium (Cd) by a novel Cd-associated and Cd-induced molecule in the stem of common reed.
abstract: Common reed (Phragmites australis) is a phytoremediator tolerant to heavy metals. In this study, we found that 70% of the cadmium (Cd) found in the stem of common reed exists in a soluble form, with more than half of the soluble Cd in the 10- to 50-kDa fraction. Based on an enzyme degradation assay, the major component of the Cd-associated molecule is assumed to be an amylopectin-like α-glucan. This molecule may associate with Cd via the carboxyl group, rather than the thiol group. The conditions required for the disengagement of Cd from the 10- to 50-kDa fraction indicated that disulfide bonds and other intramolecular interactions may contribute to maintaining the proper conformation of the molecule and to stabilizing its association with Cd. Accumulation of the Cd-associated molecule was induced by Cd stress, and the molecule was found to be also associated with Cu and Fe. Thus, we have identified a novel mechanism of Cd-pooling, namely, the association of Cd with an α-glucan-like molecule in reed stem.
authors.affiliation: Department of Applied Biology and Chemistry, Faculty of Applied Bio-Science, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156-8502, Japan. Electronic address: khiguchi@nodai.ac.jp.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Higuchi
authors.forename: Masahisa
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Suzuka
authors.initials: S
authors.lastname: Nakata
authors.forename: Ami
authors.initials: A
authors.lastname: Tanabe
authors.forename: Sayaka
authors.initials: S
authors.lastname: Fukawa
authors.forename: Masatake
authors.initials: M
authors.lastname: Kanai
authors.forename: Eitaro
authors.initials: E
authors.lastname: Miwa
mesh_terms: D002104:Cadmium / Q000302:isolation & purification* / Q000633:toxicity*; D005591:Chemical Fractionation; D004220:Disulfides / Q000378:metabolism; D005936:Glucans / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008623:Mercaptoethanol / Q000494:pharmacology; D008970:Molecular Weight; D010710:Phosphates / Q000378:metabolism; D053147:Plant Exudates / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006109:Poaceae / Q000187:drug effects / Q000378:metabolism*; D012995:Solubility; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014462:Ultrafiltration
chemical_list: D004220:Disulfides; D005936:Glucans; D010710:Phosphates; D053147:Plant Exudates; D013438:Sulfhydryl Compounds; D002104:Cadmium; D008623:Mercaptoethanol
keywords: 2-morpholinoethanesulfonic acid; BCA; Cadmium; Copper; Detoxification; Iron; MES; bicinchoninic acid; α-Glucan