The basic helix-loop-helix/PAS factor Sim is associated with hsp90: Implications for regulation by interaction with partner factors

Jacqueline McGuire, Pascal Coumailleau, Murray L. Whitelaw, Jan Åke Gustafsson, Lorenz Poellinger

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Sim is a Drosophila developmental basic helix-loop-helix (bHLH) transcription factor containing a Per-Arnt-Sim (PAS) region of homology. Here we demonstrate that Sim, in analogy to the structurally related hHLH/PAS dioxin receptor, was stably associated with the molecular chaperone hsp90. In the case of the dioxin receptor, release of hsp90 and derepression of receptor function appear to be regulated by ligand binding and dimerization with Arnt, a non-hsp90-associated bHLH/PAS factor. Dimerization with Arnt very efficiently disrupted Sim-hsp90 interaction, a process that required both the bHLH and PAS dimerization motifs of Arnt. Moreover, hsp90 was also released upon dimerization of Sim with the Drosophila PAS factor Per, whereas the hsp90-associated dioxin receptor failed to interact with Sim. These results indicate that hsp90 may play a role in conditional regulation of Sim function, and that Per and possibly bHLH/PAS partner factors may activate Sim by inducing release of hsp90 during the dimerization process.

Original languageEnglish (US)
Pages (from-to)31353-31357
Number of pages5
JournalJournal of Biological Chemistry
Volume270
Issue number52
DOIs
StatePublished - Dec 29 1995

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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