Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber
The excess amounts of heavy metals are toxic to various physiological processes in plants. Plant metallothioneins (MTs) are low molecular weight, cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions. In this study, we characterized CsMT4, a plant t...
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2019-05-01
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doaj-948e4ee67c53491d8c7bf013d3b4e2a12021-04-02T11:20:58ZengKeAi Communications Co., Ltd.Horticultural Plant Journal2468-01412019-05-0153120128Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in CucumberLing Duan0Jingwen Yu1Li Xu2Ping Tian3Xin Hu4Xiaomei Song5Yu Pan6Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaKey Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaKey Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaKey Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaKey Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaKey Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaCorresponding author. Tel.: +86 23 68250227; Key Laboratory of Horticulture Science for Southern Mountainous Regions, Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400715, ChinaThe excess amounts of heavy metals are toxic to various physiological processes in plants. Plant metallothioneins (MTs) are low molecular weight, cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions. In this study, we characterized CsMT4, a plant type 4 MT gene identified in a complementary DNA (cDNA) library prepared from young cucumber (Cucumis sativus) fruit. CsMT4 encodes a 90 amino acid protein with a predicted molecular mass of 9.028 kD. CsMT4 contains 17 cysteine residues in three highly conserved cysteine-rich domains. In contrast to the structures of other MTs, the highly conserved amino acid pattern CxCxxxCxCxxCxC is present in the middle of CsMT4. Furthermore, CsMT4 was markedly induced in various tissues by various concentrations of Cd2+ and Zn2+ (> 1.0 mmol•L−1). Similar to AtMT4b function, heterologous expression of CsMT4 in E. coli could also improved its tolerance to Cd2+ and led to increased uptake of Cd2+, and the rate of Cd2+ uptake was the highest in cells expressing a phytochelatin-like peptide. Our findings demonstrate that CsMT4 might be obviously induced by the metal stress in cucumber, and improves tolerance to Cd ions but not Zn ions when heterologously expressed in E. coli, and suggest that the composition and arrangement of N-terminal Cys-residues in MT4 are associated with their binding capacity and preference for different metal ions. Keywords: Cucumber, CsMT4, Metallothionein, Metal-binding properties, Heterologous expressionhttp://www.sciencedirect.com/science/article/pii/S2468014119300962 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ling Duan Jingwen Yu Li Xu Ping Tian Xin Hu Xiaomei Song Yu Pan |
spellingShingle |
Ling Duan Jingwen Yu Li Xu Ping Tian Xin Hu Xiaomei Song Yu Pan Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber Horticultural Plant Journal |
author_facet |
Ling Duan Jingwen Yu Li Xu Ping Tian Xin Hu Xiaomei Song Yu Pan |
author_sort |
Ling Duan |
title |
Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber |
title_short |
Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber |
title_full |
Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber |
title_fullStr |
Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber |
title_full_unstemmed |
Functional Characterization of a Type 4 Metallothionein Gene (CsMT4) in Cucumber |
title_sort |
functional characterization of a type 4 metallothionein gene (csmt4) in cucumber |
publisher |
KeAi Communications Co., Ltd. |
series |
Horticultural Plant Journal |
issn |
2468-0141 |
publishDate |
2019-05-01 |
description |
The excess amounts of heavy metals are toxic to various physiological processes in plants. Plant metallothioneins (MTs) are low molecular weight, cysteine-rich metal-binding proteins that play important roles in the detoxification of heavy metal ions. In this study, we characterized CsMT4, a plant type 4 MT gene identified in a complementary DNA (cDNA) library prepared from young cucumber (Cucumis sativus) fruit. CsMT4 encodes a 90 amino acid protein with a predicted molecular mass of 9.028 kD. CsMT4 contains 17 cysteine residues in three highly conserved cysteine-rich domains. In contrast to the structures of other MTs, the highly conserved amino acid pattern CxCxxxCxCxxCxC is present in the middle of CsMT4. Furthermore, CsMT4 was markedly induced in various tissues by various concentrations of Cd2+ and Zn2+ (> 1.0 mmol•L−1). Similar to AtMT4b function, heterologous expression of CsMT4 in E. coli could also improved its tolerance to Cd2+ and led to increased uptake of Cd2+, and the rate of Cd2+ uptake was the highest in cells expressing a phytochelatin-like peptide. Our findings demonstrate that CsMT4 might be obviously induced by the metal stress in cucumber, and improves tolerance to Cd ions but not Zn ions when heterologously expressed in E. coli, and suggest that the composition and arrangement of N-terminal Cys-residues in MT4 are associated with their binding capacity and preference for different metal ions. Keywords: Cucumber, CsMT4, Metallothionein, Metal-binding properties, Heterologous expression |
url |
http://www.sciencedirect.com/science/article/pii/S2468014119300962 |
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