Characterization and comparison of metal accumulation in two Escherichia coli strains expressing either CopA or MntA, heavy metal-transporting bacterial P-type adenosine triphosphatases
MntA from Lactobacillus plantarum and copA from Enterococcus hirae both encode membrane proteins that are members of the P-type family of adenosine triphosphatases (ATPases). Both transporters act as metal importers to take up nutritionally required substrates; MntA translocates Mn(II) and CopA translocates Cu(I). Both ATPases can also translocate secondary substrates, Cd(II) and Ag(I), respectively. Although functionally and sequentially similar, these ATPases differ in several key residues and in their membrane topologies. The bioaccumulation properties of these two proteins were examined by coexpressing the transporters with overexpressed metallothionein in Escherichia coli cells, a system that has previously shown high levels of substrate-specific uptake. Both strains exhibited rapid metal accumulation, both saturated at around 50 µM metal, and both displayed temperature-sensitive uptake. However, the transporters responded differently when external conditions were varied; MntA displayed increased sensitivity to ionic strength, while CopA was more pH sensitive and more inhibited by chelating agents. The differences in accumulation are likely owing to structural differences in the transmembrane region of these two ATPases.
Index EntriesIon transport P-type adenosine triphosphatase copper cadmium genetic engineering metallothionein lactobacillus enterococcus Escherichia coli
Romeyer, F. M., Jacobs, F. A., Masson, L., Hanna, Z., and Brosseau, R. (1988), J. Biotech.
, 207–220.CrossRefGoogle Scholar
Krishnaswamy, R. and Wilson, D. B. (2000), Appl. Environ. Microbiol.
), 5383–5386.PubMedCrossRefGoogle Scholar
Chen, S. and Wilson, D. B. (1997), Appl. Environ. Microbiol.
), 2442–2445.PubMedGoogle Scholar
Hao, Z., Reiske, H. R., and Wilson, D. B. (1999), Appl. Environ. Microbiol.
), 4741–4745.PubMedGoogle Scholar
Solioz, M. and Odermatt, A. (1995), J. Biol. Chem.
), 9217–9221.PubMedCrossRefGoogle Scholar
Axelsen, K. B. and Palmgren, M. G. (1998), J. Mol. Evol.
), 84–101.PubMedCrossRefGoogle Scholar
Odermatt, A., Suter, H., Krapp, R., and Solioz, M. (1993), J. Biol. Chem.
), 12,775–12,779.Google Scholar
Jobling, M. G. and Holmes, R. K. (1990), Nucleic Acids Res.
), 5315, 5316.PubMedCrossRefGoogle Scholar
Hao, Z., Chen, S., and Wilson, D. B. (1999), Appl. Environ. Microbiol.
), 4746–4752.PubMedGoogle Scholar
Smith, D. B. and Johnson, K. S. (1988), Gene
), 31–40.PubMedCrossRefGoogle Scholar
Yanisch-Perron, C., Vieira, J., and Messing, J. (1985), Gene
), 103–119.PubMedCrossRefGoogle Scholar
Lutsenko, S. and Kaplan, J. H. (1995), Biochemistry
), 15,607–15,613.CrossRefGoogle Scholar
Solioz, M. and Vulpe, C. (1996), Trends Biochem. Sci.
), 237–241.PubMedCrossRefGoogle Scholar
Rulisek, L. and Vondrasek, J. (1998), J. Inorg. Biochem.
), 115–127.PubMedCrossRefGoogle Scholar
Cooksey, D. A. (1993), Mol. Microbiol.
), 1–5.PubMedCrossRefGoogle Scholar
Laddaga, R. A. and Silver, S. (1985), J. Bacteriol.
), 1100–1105.PubMedGoogle Scholar
Foulkes, E. C. (1988), Toxicology
), 263–272.PubMedCrossRefGoogle Scholar
Morel, F. M. M. (1983), Principles of Aquatic Chemistry
, John Wiley & Sons, New York.Google Scholar
Chen, S. and Wilson, D. B. (1997), Biodegradation
), 97–103.PubMedCrossRefGoogle Scholar