Metal-induced expressing of mammal Metallothionein-1 gene in cyanobacteria to promote cadmium-binding preferences |
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Authors: | X -X Guo D -J Shi X -D Xu Y -X Ouyang B -G Ru |
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Institution: | (1) National Laboratory of Protein and Plant Genetic Engineering, Peking University, Beijing 100871, China, CN;(2) Research Center of Photosynthesis, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China e-mail: cyanoshi@public.bta.net.cn Fax: +86-010-62590833, CN;(3) MSU-DOE Plant Research Laboratory, Michigan State University, MI 48824-1312, USA, US |
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Abstract: | The metal(zinc)-inducible smtA gene promoter (smt O-P) from cyanobacteria was applied for the expression of mouse MT-1 cDNA in the filamentous cyanobacterium Anabaena sp. PCC 7120 to enhance its metal-binding capability and to change its main binding specificity from zinc to cadmium. Shuttle
expression vector pKT-MRE transformed the cyanobacterial cells by triparent conjugal transfer. Positive clones were screened
and identified by streptomycin, DNA dot blot, SDS-PAGE and Western blot analysis. Photosynthetic oxygen evolution and metal
atom absorption indicated that under the cadmium stress the metal-induced expression of foreign mMT-1 doubled their cadmium
resistance and developed cells showing a much higher preference to absorb cadmium other than zinc in medium. The cadmium content
in cell extract rose from 11% to 36%, and the cadmium cleared from media by transgenic cells rose from 18% to 62%. There was
only a slight enhancement for zinc binding in the wild or transgenic type.
Received: 1 March 1999 / Received last revision: 9 July 1999 / Accepted: 1 August 1999 |
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