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Ethylene-inducible DNA binding proteins that interact with an ethylene-responsive element
1Plant Molecular Biology Laboratory, National Institute of Bioscience and Human Technology, Ibaraki, Japan.
The Plant Cell
|February 1, 1995
Summary
Ethylene-responsive element binding proteins (EREBPs) bind to the GCC box, a key DNA sequence regulating plant defense genes. These novel proteins are induced by ethylene and are conserved across plant species.
Area of Science:
- Plant molecular biology
- Gene regulation
- Biochemistry
Background:
- Ethylene is a plant hormone regulating various developmental processes, including defense responses.
- Pathogenesis-related (PR) protein genes are often induced by ethylene in response to stress.
- A conserved DNA sequence, the GCC box, is found in the upstream regions of ethylene-inducible genes.
Purpose of the Study:
- To identify the DNA sequence responsible for ethylene responsiveness in plant genes.
- To isolate and characterize proteins that bind to the GCC box.
- To investigate the nature and evolutionary conservation of these DNA-binding proteins.
Main Methods:
- Incorporation of the GCC box into a heterologous promoter to test for ethylene responsiveness.
- Competitive gel retardation assays using tobacco nuclear extracts to assess DNA binding specificity.
- Isolation and sequencing of cDNAs encoding GCC box-binding proteins.
- Bioinformatic analysis of deduced protein sequences.
- RNA gel blot analysis to study gene expression patterns.
Main Results:
- The GCC box (TAAGAGCCGCC) is essential for conferring ethylene responsiveness to a heterologous promoter.
- DNA-binding activity specific to the GCC box was detected in tobacco nuclear extracts.
- Four distinct cDNAs encoding GCC box-binding proteins, named ethylene-responsive element binding proteins (EREBPs), were isolated.
- EREBPs share a conserved 59-amino acid DNA-binding domain with no homology to known transcription factor motifs.
- Homologous DNA-binding domains are present in proteins from various plant species, indicating evolutionary conservation.
- Ethylene induction of EREBP mRNA accumulation was observed, with distinct expression patterns for each EREBP.
Conclusions:
- The GCC box is a critical cis-acting element mediating ethylene-induced gene expression in plants.
- EREBPs represent a novel class of plant transcription factors that specifically bind the GCC box.
- The conserved DNA-binding domain suggests a fundamental role for EREBP-like proteins in plant hormone signaling across diverse species.
- Differential expression of EREBPs implies specialized roles in ethylene-mediated responses.