RRC ID 6951
著者 Zeitoun-Ghandour S, Charnock JM, Hodson ME, Leszczyszyn OI, Blindauer CA, Stürzenbaum SR.
タイトル The two Caenorhabditis elegans metallothioneins (CeMT-1 and CeMT-2) discriminate between essential zinc and toxic cadmium.
ジャーナル FEBS J
Abstract The nematode Caenorhabditis elegans expresses two metallothioneins (MTs), CeMT-1 and CeMT-2, that are believed to be key players in the protection against metal toxicity. In this study, both isoforms were expressed in vitro in the presence of either Zn(II) or Cd(II). Metal binding stoichiometries and affinities were determined by ESI-MS and NMR, respectively. Both isoforms had equal zinc binding ability, but differed in their cadmium binding behaviour, with higher affinity found for CeMT-2. In addition, wild-type C. elegans, single MT knockouts and a double MT knockout allele were exposed to zinc (340 microm) or cadmium (25 microm) to investigate effects in vivo. Zinc levels were significantly increased in all knockout strains, but were most pronounced in the CeMT-1 knockout, mtl-1 (tm1770), while cadmium accumulation was highest in the CeMT-2 knockout, mtl-2 (gk125) and the double knockout mtl-1;mtl-2 (zs1). In addition, metal speciation was assessed by X-ray absorption fine-structure spectroscopy. This showed that O-donating, probably phosphate-rich, ligands play a dominant role in maintaining the physiological concentration of zinc, independently of metallothionein status. In contrast, cadmium was shown to coordinate with thiol groups, and the cadmium speciation of the wild-type and the CeMT-2 knockout strain was distinctly different to the CeMT-1 and double knockouts. Taken together, and supported by a simple model calculation, these findings show for the first time that the two MT isoforms have differential affinities towards Cd(II) and Zn(II) at a cellular level, and this is reflected at the protein level. This suggests that the two MT isoforms have distinct in vivo roles.
巻・号 277(11)
ページ 2531-42
公開日 2010-6-1
DOI 10.1111/j.1742-4658.2010.07667.x
PII EJB7667
PMID 20553489
MeSH Animals Cadmium / metabolism Cadmium / toxicity* Caenorhabditis elegans / drug effects Caenorhabditis elegans / genetics Caenorhabditis elegans / metabolism* Caenorhabditis elegans Proteins / drug effects Caenorhabditis elegans Proteins / metabolism* Gene Knockdown Techniques Helminth Proteins / genetics Helminth Proteins / metabolism Kinetics Metallothionein / deficiency Metallothionein / genetics Metallothionein / metabolism* Models, Biological Protein Binding Protein Isoforms / genetics Protein Isoforms / metabolism X-Ray Absorption Spectroscopy Zinc / metabolism*
IF 4.392
引用数 48
WOS 分野 BIOCHEMISTRY & MOLECULAR BIOLOGY
リソース情報
線虫 tm1770