title: High cadmium-binding ability of a novel Colocasia esculenta metallothionein increases cadmium tolerance in Escherichia coli and tobacco.
abstract: Experimental evidence in vivo as to the functional roles and binding properties to cadmium (Cd) of type-2 plants metallothionein (MT) has been limited thus far. We investigated the biological role of metallothionein from Colocasia esculenta (CeMT2b) in Escherichia coli and tobacco, and developed a new model for the relationship between Cd tolerance and Cd-binding ability. Heterologous expression of CeMT2b in Escherichia coli greatly enhanced Cd tolerance and accumulated Cd content as compared to control cells. The molecular weight of CeMT2b increased with Cd, and CeMT2b bound up to 5.96±1 molar ratio (Cd/protein). Under Cd stress, transgenic tobacco plants displayed much better seedling growth and high Cd accumulation than the wild type. The presence of an extra CXC motif in CeMT2b contributed to the enhanced Cd-tolerance. The present study provides the first insight into the ability of type-2 plant MT to bind physiological Cd.
authors: Bio-Energy Research Institute, Chonnam National University, Gwangju, Korea.
authors: Yeon-Ok
authors: YO
authors: Kim
authors: Darshan H
authors: DH
authors: Patel
authors: Dae-Seok
authors: DS
authors: Lee
authors: Younho
authors: Y
authors: Song
authors: Hyeun-Jong
authors: HJ
authors: Bae
mesh_terms: D000595:Amino Acid Sequence; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity*; D002614:Chelating Agents / Q000737:chemistry / Q000378:metabolism; D031060:Colocasia / Q000235:genetics*; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D013312:Stress, Physiological / Q000187:drug effects; D014026:Nicotiana / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D002614:Chelating Agents; D010940:Plant Proteins; D002104:Cadmium; D008668:Metallothionein