MerR |
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PFAM accession number: | PF00376 |
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Interpro abstract (IPR000551): | The merR-type HTH domain is a DNA-binding, winged helix-turn-helix (wHTH) domain of about 70 residues present in the merR family of transcriptional regulators [ (PUBMED:2492496) ]. MerR-type regulators are present in diverse bacterial genera, in the cytoplasm. The helix-turn-helix DNA-binding motif is located in the N-terminal part of these transcriptional regulators and is followed by a coiled-coil region. The C-terminal part of merR-type regulators contains effector binding regions that are specific to the effector recognised. Most merR-type transcriptional regulators respond to environmental stimuli, like heavy metals, oxidative stress or antibiotics and a subgroup of metalloregulators are bacterial transcription activators that respond to metal ions [ (PUBMED:12829265) ]. Several structures of merR-type transcriptional regulators have been resolved and their N-terminal DNA-binding domains are ascribed to the superfamily of winged-helix proteins, containing a four-helix (H) bundle and a three-stranded antiparallel beta-sheet (B) in the topology: B1-H1-H2-B2-B3-H3-H4 [ (PUBMED:12186881) ]. The helix-turn-helix motif comprises the first and second helices, the second being called the recognition helix. The HTH is involved in DNA-binding into the major groove, where the recognition helix makes most DNA-contacts. The second DNA-binding element is wing W1, composed of the second and third beta-strands and their connecting loop. The third DNA-binding element, wing W2, is not a loop like in typical winged-helix proteins, but another H-T-H motif formed by helices three and four. In a typical merR regulator, the HTH and two wings bind the promoter of the regulated operon between the -35 and -10 regions in a spacer of 19/20 bp and longer than usual, distorting the operator DNA and causing RNA polymerase to initiate transcription [ (PUBMED:12829265) ]. Most merR-like transcriptional regulators are dimers. Some proteins known to contain a merR-type HTH domain:
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GO process: | regulation of transcription, DNA-templated (GO:0006355) |
GO function: | DNA binding (GO:0003677) |
This is a PFAM domain. For full annotation and more information, please see the PFAM entry MerR