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- Title
Discrimination between two rice metallothionein isoforms belonging to type 1 and type 4 in metal-binding ability.
- Authors
Nezhad, Rezvan Mohammadi; Shahpiri, Azar; Mirlohi, Aghafakhr
- Abstract
Metallothioneins ( MTs) are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. Plants have several MT isoforms, which are classified into four types based on the arrangement of Cys residues. In this study, two rice ( Oryza sativa) MT isoforms, Os MTI-1b and Os MTII-1a from type 1 and type 4, respectively, were heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione- S-transferase ( GST). Transformed cells expressing GST- Os MTI -1b showed increased tolerance to Ni2+, Cd2+, and Zn2+ and accumulated more metal ions compared with cells expressing GST alone. However, heterologous expression of GST- Os MTII-1a had no significant effects on metal tolerance or ion accumulation. The UV absorption spectra and competitive reactions of in vitro Cd-incubated proteins with 5-5′-dithiobis(2-nitrobenzoic) acid revealed that GST- Os MTI -1b, but not GST- Os MTII-1a, is able to form Cd-thiolate clusters. Furthermore, heterologous expression of both GST- Os MTI-1b and GST- Os MTII-1a conferred H2 O2 tolerance to E. coli cells. Taken together, the results presented here show that two different rice MT isoforms belonging to type 1 and type 4 differ in Ni2+, Cd2+, and Zn2+ binding abilities, but they may have overlapping function in protection of cells against oxidative stress.
- Subjects
METALLOTHIONEIN; METAL-binding peptides; PROTEINS; VALUE-added tax; FOODBORNE diseases; NITROBENZOIC acid
- Publication
Biotechnology & Applied Biochemistry, 2013, Vol 60, Issue 3, p275
- ISSN
0885-4513
- Publication type
Article
- DOI
10.1002/bab.1078