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The cryptic enhancer elements of the tCUP promoter
Keqiang Wu1, Ming Hu, Teresa Martin
1Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, Ontario Canada K1A 0C6.
Plant Molecular Biology
|February 27, 2003
Summary
Cryptic gene regulatory elements in tobacco plants are functionally similar to known gene expression elements. A truncated promoter fragment revealed two enhancers, including a novel constitutive enhancer (Cce), crucial for gene expression.
Area of Science:
- Plant Molecular Biology
- Gene Regulation
- Plant Genomics
Background:
- Cryptic regulatory elements in plant genomes are poorly understood.
- Understanding these elements is key to deciphering gene expression control.
- The tCUP promoter from tobacco serves as a model for cryptic promoter investigation.
Purpose of the Study:
- To investigate the functional equivalence and organization of cryptic gene regulatory elements.
- To identify and characterize enhancer elements within the tCUP promoter responsible for constitutive expression.
Main Methods:
- Analysis of GUS reporter gene expression in transgenic Arabidopsis plants.
- Construction and analysis of 5' deletion and linker-scan mutagenesis series.
- Electrophoretic mobility-shift assays (EMSA) to identify protein-DNA interactions.
Main Results:
- A truncated -394tCUP promoter fragment contained all necessary information for strong constitutive expression.
- Two enhancer elements were identified: a long AT-rich region and a novel 21 bp cryptic constitutive enhancer (Cce).
- The Cce element specifically binds tobacco nuclear proteins and functions dependently on the AT-rich element, indicating combinatorial control.
Conclusions:
- Cryptic gene regulatory elements are functionally equivalent and similarly organized to known plant gene expression elements.
- The AT-rich region and the Cce element together drive the constitutive transcriptional activity of the tCUP promoter.
- This study elucidates the mechanism of constitutive expression mediated by cryptic elements, offering insights into plant gene regulation.