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Published on: September 27, 2012
Multiple DNA-Protein Complexes at a Circadian-Regulated Promoter Element
1National Science Foundation Center for Biological Timing, University of Virginia, Charlottesville, Virginia, 22903.
The Plant Cell
|December 1, 1995
Summary
Researchers identified a 36-base pair DNA sequence in Arabidopsis that controls circadian regulation of the CAB2 gene. This region, containing a CCAAT box, binds three transcription factors crucial for clock-controlled gene expression.
Area of Science:
- Plant molecular biology
- Circadian rhythms
- Chlorophyll a/b binding proteins (CAB)
Background:
- CAB genes encode light-harvesting proteins in chloroplasts.
- CAB2 gene transcription in Arabidopsis is regulated by a circadian oscillator with near-24-hour oscillations.
- Previous studies indicated a promoter region (-111 to -38) confers circadian regulation.
Purpose of the Study:
- To dissect the CAB2 promoter region responsible for circadian regulation.
- To identify DNA-binding factors involved in clock-controlled transcription.
- To elucidate the molecular mechanism of circadian control over CAB gene expression.
Main Methods:
- Deletion analysis of the CAB2 promoter in transgenic tobacco.
- Characterization of DNA-binding complexes using Arabidopsis whole-cell extracts.
- In vivo analysis of cab2::luc fusion constructs in transgenic Arabidopsis.
Main Results:
- A 36-bp sequence within the CAB2 promoter confers circadian regulation.
- This critical element overlaps a conserved CCAAT box.
- Five DNA-binding complexes were identified, with three putative transcription factors binding to the 36-bp region.
Conclusions:
- A specific 36-bp cis-regulatory element controls CAB2 circadian transcription.
- This element acts as a docking site for multiple transcription factors.
- These factors are likely key components in the signal transduction pathway linking the circadian clock to CAB gene expression.
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