Cyanobacterial metallothionein gene expressed in Escherichia coli. Metal-binding properties of the expressed protein. |
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Authors: | J Shi W P Lindsay J W Huckle A P Morby N J Robinson |
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Affiliation: | Department of Biological Sciences, University of Durham, UK. |
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Abstract: | The recently isolated Synechococcus gene smtA encodes the only characterised prokaryotic protein designated to be a metallothionein (MT). To examine the metal-binding properties of its product the smtA gene was expressed in Escherichia coli as a carboxyterminal extension of glutathione-S-transferase. The pH of half dissociation of Zn, Cd and Cu ions from the expressed protein was determined to be 4.10, 3.50, 2.35, respectively, indicating a high affinity for these ions (in particular for Zn in comparison to mammalian MT). E. coli expressing this gene showed enhanced (ca. 3-fold) accumulation of Zn. |
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