Metalloregulatory DNA-binding protein encoded by the merR gene: Isolation and characterization

T. O'Halloran, C. Walsh

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


The MerR protein mediates the induction of the mercury resistance phenotype in bacteria; it has been isolated in order to study the effects of metal-ion induced changes in the metabolism of prokaryotic cells at the molecular level. After DNA sequences responsible for negative autoregulation were removed, the 16-kilodalton protein was overproduced and purified to more than 90 percent homogeneity by a salt extraction procedure that yields about 5 milligrams of protein per gram of cells. Complementation data, amino terminal analysis, gel filtration, and deoxyribonuclease I protection studies demonstrate that the purified merR gene product is a dimer under nondenaturing conditions and that it binds specifically to DNA, in the presence and absence of mercury, at a palindromic site which is directly between the -10 and -35 regions of the structural genes and adjacent to its own promoter. These initial results indicate that MerR is a DNA-binding metalloregulatory protein that plays a central role in this heavy metal responsive system and they delineate an operator site in the mer operon.

Original languageEnglish (US)
Pages (from-to)211-214
Number of pages4
Issue number4785
StatePublished - 1987

ASJC Scopus subject areas

  • General


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