کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2817898 | 1160018 | 2012 | 8 صفحه PDF | دانلود رایگان |
Salicornia brachiata is an extreme halophyte growing luxuriantly in the coastal marshes and frequently exposed to various abiotic stresses including heavy metals. A full length type 2 metallothionein (SbMT-2) gene was isolated using RACE and its copy number was confirmed by southern blot analysis. Transcript expression of SbMT-2 gene was analyzed by semi-quantitative Rt-PCR and real time quantitative (qRT) PCR. Expression of SbMT-2 gene was up-regulated concurrently with zinc, copper, salt, heat and drought stress, down regulated by cold stress while unaffected under cadmium stress. Heterologous expression of SbMT-2 gene enhances metal accumulation and tolerance in E. coli. Metal-binding characteristics of SbMT-2 protein show its possible role in homeostasis and/or detoxification of heavy metals. Significant tolerance was observed by E. coli cells expressing recombinant SbMT-2 for Zn++, Cu++ and Cd++ compared to cells expressing GST only. Sequestration of zinc was 4-fold higher compared to copper and in contrast SbMT-2 inhibits the relative accumulation of cadmium by 1.23-fold compared to GST protein. Fusion protein SbMT-2 showed utmost affinity to zinc (approx. 2.5 fold to Cu++ and Cd++) followed by copper and cadmium ions with same affinity. Halophyte S. brachiata has inherent resilience of varying abiotic tolerance therefore SbMT-2 gene could be a potential candidate to be used for enhanced metal tolerance and heavy metal phytoremediation.
► SbMT-2 gene (421 bp): 5′ UTR—88 bp; ORF—237 bp encoding 78 amino acids.
► SbMT-2 expression: [↑]—Zn++, Cu++, salt, heat, drought and [↓]—cold.
► Metal tolerance and binding capacity: Zn++ > Cu++ > Cd++.
► SbMT-2 expression in E. coli.: Increased metal tolerance and metal ion accumulation.
► SbMT-2: A potential candidate for metal tolerance and heavy metal phytoremediation.
Journal: Gene - Volume 499, Issue 2, 15 May 2012, Pages 280–287