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Protein‐protein interaction via PAS domains: role of the PAS domain in positive and negative regulation of the bHLH/PAS dioxin receptor‐Arnt transcription factor complex.
Author(s) -
Lindebro M.C.,
Poellinger L.,
Whitelaw M.L.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb07359.x
Subject(s) - aryl hydrocarbon receptor nuclear translocator , biology , pas domain , transcription factor , genetics , microbiology and biotechnology , gene , aryl hydrocarbon receptor
Gene regulation by dioxins is mediated by the dioxin receptor‐Arnt heterodimer, a ligand generated complex of two basic helix‐loop‐helix (bHLH)/Per‐Arnt‐Sim (PAS) transcription factors. By using dioxin receptor chimeras where the dimerization and DNA binding bHLH motif has been replaced by a heterologous DNA binding domain, we have detected an ability of Arnt to interact with the dioxin receptor via the PAS domain in a mammalian ‘hybrid interaction’ system. By coimmunoprecipitation assays, we have confirmed the ability of PAS domains of the dioxin receptor and Arnt to mediate independent heterodimerization in vitro. Selectivity for PAS dimerization was noted in our hybrid interaction system, as dioxin receptor or Arnt PAS‐mediated homodimers were not detected. Surprisingly, however, the PAS domain of Per could dimerize with both the dioxin receptor and Arnt subunits in vitro, and disrupt the ability of these subunits to form a DNA binding heterodimer. Moreover, ectopic expression of Per blocked dioxin signalling in mammalian cells. The PAS domains of the dioxin receptor and Arnt are therefore novel dimerizing regions critical in formation of a functional dioxin receptor‐Arnt complex, while the PerPAS domain is a potential negative regulator of bHLH/PAS factor function.