Construction of Zn2+/Cd2+ hypersensitive cyanobacterial mutants lacking a functional metallothionein locus

Eukaryotic metallothioneins (MTs) have been extensively studied, but the precise functions of most of these molecules are not yet fully understood. Prokaryotes are often more tractable for the analysis of gene function and we report here the generation of mutants of Synechococcus PCC 7942 (strain R2...

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Bibliographic Details
Published in:The Journal of biological chemistry 1993-02, Vol.268 (6), p.4494-4498
Main Authors: TURNER, J. S, MORBY, A. P, WHITTON, B. A, AMIT GUPTA, ROBINSON, N. J
Format: Article
Language:English
Subjects:
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Cadmium - pharmacology
Chromosomes, Bacterial
Cyanobacteria - drug effects
Cyanobacteria - genetics
Fundamental and applied biological sciences. Psychology
Genes, Bacterial
Genetic Complementation Test
Metalloproteins
Metallothionein - genetics
Metallothionein - metabolism
Mutation
Other metalloproteins
Phenotype
Plasmids
Proteins
Transcription, Genetic
Zinc - pharmacology
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Summary:Eukaryotic metallothioneins (MTs) have been extensively studied, but the precise functions of most of these molecules are not yet fully understood. Prokaryotes are often more tractable for the analysis of gene function and we report here the generation of mutants of Synechococcus PCC 7942 (strain R2-PIM8) deficient in the MT locus, smt. Viability of these mutants, designated R2-PIM8 (smt), reveals that prokaryotic MT performs no "vital" role (such as donation of metals to metallo-proteins) in Synechococcus. R2-PIM8 (smt) has reduced (approximately 5-fold) tolerance to elevated Zn2+, with detectable hypersensitivity to Cd2+. Restoration of Zn2+ tolerance was used as a selectable marker to isolate recombinants derived from R2-PIM8(smt) after reintroduction of a linear DNA fragment containing an uninterrupted smt locus. These smt-complemented cells also exhibited restored Cd2+ tolerance. Hypersensitivity to Cu2+ was not detected in R2-PIM8(smt) indicating independence of Cu2+ resistance from smt mediated metal (Zn2+/Cd2+) tolerance.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)53636-X