Abstract
The phytohormone ethylene is widely involved in many developmental processes and is a crucial regulator of defense responses against biotic and abiotic stresses in plants. Ethylene-responsive element binding protein, a member of the APETALA2/ethylene response factor (AP2/ERF) superfamily, is a transcription factor that regulates stress-responsive genes by recognizing a specific cis-acting element of target DNA. A previous study showed only the NMR structure of the AP2/ERF domain of AtERF100 in complex with a GCC box DNA motif. In this report, we determined the crystal structure of AtERF96 in complex with a GCC box at atomic resolution. We analyzed the binding residues of the conserved AP2/ERF domain in the DNA recognition sequence. In addition to the AP2/ERF domain, an N-terminal α-helix of AtERF96 participates in DNA interaction in the flanking region. We also demonstrated the structure of AtERF96 EDLL motif, a unique conserved motif in the group IX of AP2/ERF family, might involve in the transactivation of defense-related genes. Our study establishes the structural basis of the AtERF96 transcription factor in complex with the GCC box, as well as the DNA binding mechanisms of the N-terminal α-helix and AP2/ERF domain.
Highlights
Plants are exposed to natural environments that may negatively affect their growth and development
The results showed that the precise monomeric form (62.7 mL) was 17 kDa, which is consistent with the results of the SDS-PAGE analysis (Fig. S1D and E)
Group IX of the APETALA2/ethylene response factor (AP2/ERF) family is composed of three subgroups, IX-a, IX-b, and IX-c, characterized by the conserved motifs (CM) CMIX-3, CMIX-2, and CMIX-1, respectively (Nakano et al 2006)
Summary
Plants are exposed to natural environments that may negatively affect their growth and development. Such a group of transcription factors in plants is activated by ethylene signaling under biotic or abiotic stresses. APETALA2/ethylene response factors (AP2/ERFs) are a superfamily of plant-exclusive transcription factors involved in the ethylene-inducible response (Gutterson and Reuber 2004; Mizoi et al 2012; Najafi et al 2018). APETALA2 was first isolated from the floral development-related proteins in Arabidopsis (Jofuku et al 1994). An AP2-LIKE ERE BINDING FACTOR (ERF), known as ERE BINDING PROTEIN (EREBP), was first isolated as the GCC box-binding protein from tobacco
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