DNA distortion mechanism for transcriptional activation by ZntR, a Zn(II)-responsive MerR homologue in Escherichia coli

Caryn E. Outten, F. Wayne Outten, Thomas V. O'Halloran*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

150 Scopus citations

Abstract

MerR-like DNA distortion mechanisms have been proposed for a variety of stress-responsive transcription factors. The Escherichia coli ZntR protein, a homologue of MerR, has recently been shown to mediate Zn(II)responsive regulation of zntA, a gene involved in Zn(II) detoxification. To determine whether the MerR DNA distortion mechanism is conserved among MerR family members, we have purified ZntR to homogeneity and shown that it is a zinc receptor that is necessary and sufficient to stimulate Zn-responsive transcription at the zntA promoter. Biochemical, DNA footprinting, and in vitro transcription assays indicate that apo-ZntR binds in the atypical 20- base pair spacer region of the promoter and distorts the DNA in a manner that is similar to apo-MerR. The addition of Zn(II) to ZntR converts it to a transcriptional activator protein that introduces changes in the DNA conformation. These changes apparently make the promoter a better substrate for RNA polymerase. We propose that this zinc-sensing homologue of MerR restructures the target promoter in a manner similar to that of other stress- responsive transcription factors. The ZntR metalloregulatory protein is a direct Zn(II) sensor that catalyzes transcriptional activation of a zinc efflux gene, thus preventing intracellular Zn(II) from exceeding an optimal but as yet unknown concentration.

Original languageEnglish (US)
Pages (from-to)37517-37524
Number of pages8
JournalJournal of Biological Chemistry
Volume274
Issue number53
DOIs
StatePublished - Dec 31 1999

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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