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Updated: Jul 28, 2026
12:36
Chromatin Immunoprecipitation Assay for the Identification of Arabidopsis Protein-DNA Interactions In Vivo
Published on: January 15, 2016
The Arabidopsis basic/helix-loop-helix transcription factor family
Gabriela Toledo-Ortiz1, Enamul Huq, Peter H Quail
1Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
The Plant Cell
|August 5, 2003
Summary
The study identified 147 basic/helix-loop-helix (bHLH) genes in Arabidopsis, revealing extensive combinatorial interactions for transcriptional regulation. This large family of transcription factors plays a crucial role in plant development.
Area of Science:
- Plant Molecular Biology
- Genomics
- Transcription Factor Research
Background:
- Basic/helix-loop-helix (bHLH) proteins are a large superfamily of transcription factors known for regulating diverse biological processes in eukaryotes.
- Phytochrome-interacting factor 3 (PIF3) is a known component in the phytochrome signaling network, suggesting a role for bHLH proteins in light responses.
Purpose of the Study:
- To conduct a comprehensive computational analysis of the Arabidopsis genome to define the scope and features of the bHLH protein family.
- To classify the identified bHLH genes and explore their evolutionary and functional relationships.
Main Methods:
- Genome-wide computational analysis of Arabidopsis sequence databases using a defined consensus motif for bHLH identification.
- Phylogenetic analysis of bHLH domain sequences to classify genes into subfamilies.
- Analysis of chromosomal distribution, exon/intron patterns, and predicted DNA binding activities.
- Yeast two-hybrid and in vitro binding assays for PIF3 and PIF4.
Main Results:
- Identified 147 bHLH protein-encoding genes in Arabidopsis, constituting one of the largest transcription factor families.
- Classified these genes into 21 distinct subfamilies based on phylogenetic analysis of bHLH domains.
- Predicted considerable diversity in DNA binding specificities and significant sequence divergence outside the bHLH domain.
- Demonstrated that PIF3 and PIF4 can form homodimers and heterodimers that bind specifically to the G-box motif (CACGTG).
Conclusions:
- The large and diverse Arabidopsis bHLH family has the potential for extensive combinatorial interactions, enabling regulation of multiple transcriptional programs.
- The findings support a combinatorial mechanism for transcriptional regulation involving bHLH proteins in plants.
- PIF3 and PIF4 dimerization and DNA binding provide a specific example of this regulatory potential.
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