This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hamlett, N V Articles by Summers, A O Search for Related Content PubMed PubMed Citation Articles by Hamlett, N V Articles by Summers, A O

 Previous Article  |  Next Article 

J Bacteriol. 1992 October; 174(20): 6377-6385

research-article

Roles of the Tn21 merT, merP, and merC gene products in mercury resistance and mercury binding.

Department of Biology, Swarthmore College, Pennsylvania 19081.

ABSTRACT

The mercury resistance (mer) operon of the gram-negative transposon Tn21 encodes not only a mercuric reductase and regulatory genes but also two inner membrane proteins (MerT and MerC) and a periplasmic protein (MerP). Although the merT, merP, and merC genes have been implicated in Hg(II) transport, the individual roles of these genes have not been established. We created in vitro precise deletion and frameshift mutations that eliminated each of the genes singly and in combination. Our results show that both merT and merP are required for Hg(II) binding but that merC is not. Both merT and merP are required for full expression of Hg(II) resistance, but loss of merP is less deleterious than loss of merT. Furthermore, mutations eliminating both merT and merP decrease resistance more than the single mutations do. In contrast, mutating merC had no effect on Hg(II) resistance. Both the merT and merP mutations increase the threshold Hg(II) concentration for induction of merA-lacZ transcriptional fusions and cause an increase in the maximal expression level. In contrast, the merC mutation had little effect on the threshold inducing concentration of Hg(II) but decreased the level of expression. Our results show that merT and merP alone are sufficient to specify a mercury transport system. The role of merC remains obscure.

This article has been cited by other articles:

• Thilakaraj, R., Raghunathan, K., Anishetty, S., Pennathur, G. (2007). In silico identification of putative metal binding motifs. Bioinformatics 23: 267-271 [Abstract] [Full Text]  
• Qin, J., Song, L., Brim, H., Daly, M. J., Summers, A. O. (2006). Hg(II) sequestration and protection by the MerR metal-binding domain (MBD).. Microbiology 152: 709-719 [Abstract] [Full Text]  
• Song, L., Caguiat, J., Li, Z., Shokes, J., Scott, R. A., Olliff, L., Summers, A. O. (2004). Engineered Single-Chain, Antiparallel, Coiled Coil Mimics the MerR Metal Binding Site. J. Bacteriol. 186: 1861-1868 [Abstract] [Full Text]  
• Bizily, S. P., Kim, T., Kandasamy, M. K., Meagher, R. B. (2003). Subcellular Targeting of Methylmercury Lyase Enhances Its Specific Activity for Organic Mercury Detoxification in Plants. Plant Physiol. 131: 463-471 [Abstract] [Full Text]  
• Powlowski, J., Sahlman, L. (1999). Reactivity of the Two Essential Cysteine Residues of the Periplasmic Mercuric Ion-binding Protein, MerP. J. Biol. Chem. 274: 33320-33326 [Abstract] [Full Text]  
• Rensing, C., Ghosh, M., Rosen, B. P. (1999). Families of Soft-Metal-Ion-Transporting ATPases. J. Bacteriol. 181: 5891-5897 [Full Text]  
• Liebert, C. A., Hall, R. M., Summers, A. O. (1999). Transposon Tn21, Flagship of the Floating Genome. Microbiol. Mol. Biol. Rev. 63: 507-522 [Abstract] [Full Text]  
• Bizily, S. P., Rugh, C. L., Summers, A. O., Meagher, R. B. (1999). Phytoremediation of methylmercury pollution: merB expression in Arabidopsis thaliana confers resistance to organomercurials. Proc. Natl. Acad. Sci. USA 96: 6808-6813 [Abstract] [Full Text]  
• Caguiat, J. J., Watson, A. L., Summers, A. O. (1999). Cd(II)-Responsive and Constitutive Mutants Implicate a Novel Domain in MerR. J. Bacteriol. 181: 3462-3471 [Abstract] [Full Text]  
• Ravel, J., Schrempf, H., Hill, R. T. (1998). Mercury Resistance Is Encoded by Transferable Giant Linear Plasmids in Two Chesapeake Bay Streptomyces Strains. Appl. Environ. Microbiol. 64: 3383-3388 [Abstract] [Full Text]  
• Sahlman, L., Wong, W., Powlowski, J. (1997). A Mercuric Ion Uptake Role for the Integral Inner Membrane Protein, MerC, Involved in Bacterial Mercuric Ion Resistance. J. Biol. Chem. 272: 29518-29526 [Abstract] [Full Text]  
• Lin, S.-J., Pufahl, R. A., Dancis, A., O'Halloran, T. V., Culotta, V. C. (1997). A Role for the Saccharomyces cerevisiae ATX1 Gene in Copper Trafficking and Iron Transport. J. Biol. Chem. 272: 9215-9220 [Abstract] [Full Text]