Abstract
Escherichia coli K12 containing the transposon Tn5044 mer operon (merR, T, P, C, and A genes) is resistant to mercuric chloride at 30°C but sensitive to this compound at 37–41.5°C. We have studied the mechanism underlying the temperature-sensitive nature of this mercury resistance phenotype, and found that the expression of the Tn5044 merA gene coding for mercuric reductase (MerA) is severely inhibited at non-permissive temperatures. Additionally, MerA showed a considerably reduced functional activity in vivo at non-permissive temperatures. However, the temperature-sensitive character of the functioning of this enzyme in cell extracts, where it interacted with one of the low-molecular weight SH compounds rather than with the transport protein MerT (as is the case in vivo), was not apparent. These data suggest that the temperature-sensitive mercury resistance phenotype should stay under control at two stages: when the merA gene is expressed and when its product interacts with MerT to accept the mercuric ion.
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Kholodii, G., Bogdanova, E. Tn5044-Conferred Mercury Resistance Depends on Temperature: the Complexity of the Character of Thermosensitivity. Genetica 115, 233–241 (2002). https://doi.org/10.1023/A:1020185206563
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DOI: https://doi.org/10.1023/A:1020185206563