||Role of Na(+) in Transport of Hg(2+) and Induction of the Tn21 mer Operon.
Selifonova, O. V. ;
Barkay, T. ;
||University of West Florida, Pensacola. Center for Environmental Diagnostics and Bioremediation.;Environmental Research Lab., Gulf Breeze, FL.
Aquatic microbiology ;
Transport properties ;
Ion ion interactions ;
Escherichia coli ;
Bacterial genes ;
TN21 mer operon
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The effects of sodium ions on the uptake of Hg(2+) and induction of the TN21 mer operon were studied using Escherichia coli (E. coli) HMS174 harboring the reporter plasmids pRB28 and pOS14. Plasmid pRB28 carried merRT' and pOS14 carried merRTPC of the mer operon, both cloned upstream of a promoterless luciferase gene cassette in pUDC615. The bioluminescent response to 1 microM Hg(2+) was significantly inhibited in E. coli HMS174(pRB28) in minimal medium supplemented with sodium ions at 10 to 140 mM. Sodium ions appear to facilitate mercury transport. The authors propose that sodium-coupled transport of mercuric ions can be one of the mechanisms for mercury uptake by E. coli and that the Na(1+) gradient may energize the transport of Hg(2+).