Ethylene is an endogenous plant hormone that influences many aspects of plantgrowth and development. Some defense related genes that are induced byethylene contain a cis-regulatory element known as the Ethylene-Responsive Element (ERE) [1]. Sequence analysis on various ERE regionshas identified a short motif rich in G/C nucleotides, the GCC-box, essential forthe response to ethylene. This short motif is recognised by a family oftranscrition factors, the ERE binding factors (ERF) [2].
ERF proteins contain a domain of around 60 amino acids which is also found in theAPETALA2 (AP2) protein [3]. This AP2/ERF domain has been shown in variousproteins to be necessary and sufficient to bind the GCC-box [4].
The structure of the AP2/ERF domain in complex with the target DNA has beensolved [5]. The structure resembles that of bacteriophage integrases and the methyl-CpG-binding domain (MBD): a three-stranded beta-sheet and an alpha helixalmost parallel to the beta-sheet. It contacts DNA via Arg and Trp residues located in the beta-sheet.
Some proteins known to contain an AP2/ERF domain include:
- Arabidopsis thaliana ERF1 to 6.
- Tobacco ethylene-responsive element-binding proteins (EREBPs), homologues of ERF proteins.
- Arabidopsis thaliana AP2 protein. It regulates meristeme identity, floral organ specification and seed coat development.
- Arabidopsis thaliana C-repeat/dehydration-responsive element (DRE) binding factor 1 (CBF1 or DREB1) and DREB2. They bind a GCC-box-like element found in dehydratation responsive element. Binding to this element mediates cold-inducible transcription.
- Arabidopsis thaliana and maize abscisic acid (ABA)-insensitive 4 (ABI4) proteins. They bind to a GCC-box-like element found in ABA-responsive genes.
- Octadecanoid-derivative responsive catharenthus AP2-domain (ORCA2) protein. It binds a GCC-box-like element in the jasmonate responsive element of Str promoter.
- Tomato Pto-interacting proteins 4 to 6 (Pti4 to Pti6). Pti5 and 6 bind a GCC-box-like element in regulatory regions of various pathogenesis-related (PR) genes.
- Trichodesmium erythraeum, Tetrahymena thermophila, Enterobacteria phage RB49 and bacteriophage Felix 01 HNH endonucleases. HNH endonucleases are homing endonucleases that move extensively via lateral gene transfer [6].
This entry represents the AP2/ERF domain.
1. Functional analysis of DNA sequences responsible for ethylene regulation of a bean chitinase gene in transgenic tobacco. Plant Cell 1, 599-607
2. Arabidopsis ethylene-responsive element binding factors act as transcriptional activators or repressors of GCC box-mediated gene expression. Plant Cell 12, 393-404
3. The APETALA2 domain is related to a novel type of DNA binding domain. Plant Cell 7, 388-9
4. Unique mode of GCC box recognition by the DNA-binding domain of ethylene-responsive element-binding factor (ERF domain) in plant. J. Biol. Chem. 273, 26857-61
5. A novel mode of DNA recognition by a beta-sheet revealed by the solution structure of the GCC-box binding domain in complex with DNA. EMBO J. 17, 5484-96
6. From endonucleases to transcription factors: evolution of the AP2 DNA binding domain in plants. Plant Cell 16, 2265-77
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