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A novel C-terminal domain of drosophila PERIOD inhibits dCLOCK:CYCLE-mediated transcription

Dennis C Chang1, Steven M Reppert

  • 1Department of Neurobiology, University of Massachusetts Medical Center, 364 Plantation Street, Worcester, MA 01605, USA.

Current Biology : CB
|May 3, 2003
PubMed

Insights

The Drosophila circadian clock

Area of Science:

  • Chronobiology
  • Molecular Biology
  • Genetics

Background:

  • The Drosophila circadian clock relies on a negative feedback loop involving PERIOD (PER) and TIMELESS (TIM) proteins.
  • PER and TIMELESS inhibit their own transcription by interacting with dCLOCK (dCLK) and CYCLE (CYC) transcriptional activators.
  • The role of PAS domains in these interactions and the necessity of PER nuclear transport for clock function remain incompletely understood.

Purpose of the Study:

  • To investigate the critical aspects of PER-mediated transcriptional inhibition in Drosophila.
  • To functionally map the nuclear localization sequence (NLS) of PER and assess its role in nuclear transport and inhibitory activity.
  • To identify the specific domain responsible for inhibiting dCLK:CYC activity.

Main Methods:

  • Utilized Drosophila Schneider 2 (S2) cells for experimental analysis.
  • Employed deletion mutants and site-directed mutagenesis to map PER's functional domains.
  • Evaluated the impact of identified NLS on PER's nuclear transport and transcriptional inhibition.

Main Results:

  • Mapped the dCLK:CYC inhibition domain (CCID) of PER to its C terminus, downstream of the PAS domain.
  • Identified a novel NLS within the CCID of PER, crucial for its nuclear transport in S2 cells.
  • Demonstrated that nuclear transport, mediated by this novel NLS, is essential for PER's inhibitory function.

Conclusions:

  • PER inhibits dCLK:CYC-mediated transcription through a novel C-terminal domain.
  • This domain contains a potent NLS that regulates PER's nuclear localization.
  • Nuclear transport of PER is a critical regulatory step for the Drosophila circadian clock's negative feedback loop.

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