BEH2 (BES1/BZR1 HOMOLOG 2, At4g36780) is one of six members of the plant-specific BZR1/BES1 family of transcription factors (BZR1, BES1, BEH1-BEH4) that act as the nuclear output of brassinosteroid (BR) signalling. It carries the conserved N-terminal BES1_N DNA-binding domain through which family members bind BRRE and E-box promoter elements. BEH2 interacts with and is phosphorylated by GSK3-like kinases (ASKtheta, BIN2); it shifts to a dephosphorylated form in response to BR, and a stabilizing Pro222Leu substitution (BEH2m, equivalent to bzr1-1D/bes1-D) confers a constitutive BR response. Unlike BZR1 and BES1, BEH2 is constitutively nuclear regardless of its phosphorylation state and can promote nuclear accumulation of other family members by heterodimerization. Overexpression rescues the bri1-5 receptor mutant, enhances BR responses and alters expression of more than a thousand genes, many of them BR-independent. BEH2 is expressed mainly in roots and leaf margins and its own transcription is repressed by BR via BES1. No loss-of-function phenotype has been described, consistent with redundancy within the family.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000987 cis-regulatory region sequence-specific DNA binding | IBA GO_REF:0000033 | ACCEPT | Summary: IBA: cis-regulatory region sequence-specific DNA binding, inherited from the BZR/BES1 family node (BES1 AT1G19350, BZR1 AT1G75080). Reason: BZR1-family proteins bind BRRE (CGTGT/CG) and E-box (CANNTG) cis-elements via the conserved N-terminal BES1_N DNA-binding domain. BEH2 carries this domain (Pfam PF05687; region 16..97 required for DNA binding by similarity) and sits inside the PANTHER clade whose IBD is seeded by experimentally characterized BES1 and BZR1. No target-specific evidence of loss of DNA binding exists. A BEH2-specific EMSA/ChIP has not been found in the cached literature, so this rests on the phylogenetic inference, which is sound for this clade. Supporting Evidence: file:ARATH/BEH2/BEH2-uniprot.txt Required for DNA-binding file:ARATH/BEH2/BEH2-uniprot.txt Belongs to the BZR/LAT61 family. PMID:15680330 BES1 is a transcription factor that binds to and activates BR target gene promoters both in vitro and in vivo. file:ARATH/BEH2/BEH2-deep-research-manual.md No direct DNA-binding assay (EMSA/ChIP) for BEH2 itself was found in the cached |
| GO:0003700 DNA-binding transcription factor activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA: DNA-binding transcription factor activity, inherited from the BZR family node. Reason: BEH2 is a BZR1/BES1-family transcription factor; overexpression rescues bri1-5 and reprograms >1000 genes, and the protein is constitutively nuclear. Together with the conserved BES1_N DNA-binding domain this supports the inherited sequence-specific TF activity. Activator versus repressor character is not established for BEH2, so the general term is as precise as the evidence allows. Supporting Evidence: file:ARATH/BEH2/BEH2-uniprot.txt Belongs to the BZR/LAT61 family. PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression PMID:35695417 However, we can still claim that BEH2 can potentially regulate over a thousand genes directly or indirectly. |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO (IPR033264 BZR) mapping to DNA-binding transcription factor activity. Reason: Same claim as the IBA row; the BZR family signature is diagnostic for this plant-specific TF family and BEH2 behaves as a transcriptional regulator in overexpression studies. Supporting Evidence: file:ARATH/BEH2/BEH2-uniprot.txt Belongs to the BZR/LAT61 family. PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression |
| GO:0005515 protein binding | IPI PMID:37926922 Comparative analysis of BZR1/BES1 family transcription facto... | REMOVE | Summary: IPI protein binding from Kim et al. 2024 with ASK-gamma (AT3G05840), BIN2 (AT4G18710) and AT3G61140. Reason: Bare protein binding is uninformative and removed under the project protein-binding policy; the interactions themselves (BEH2 as a substrate of GSK3-like kinases) are real and are independently shown by Y2H with ASKtheta and BIN2 in PMID:20128883. Note that the With/From AT3G61140 is CSN1/FUS6 (UniProt P45432), not a GSK3-like kinase, while the paper examined interactions with GSK3-like kinases; it is probably a mis-keyed AT3G61160 (ASK-beta). Recorded as a suspected source defect for TAIR to check. Supporting Evidence: PMID:37926922 interaction with GSK3-like kinases, and heterodimeric combination PMID:20128883 BIN2 interacted with BES1, BZR1 and BEH2. |
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: IBA nucleus (is_active_in) from the BZR family node; BEH2 itself is among the descendant evidence. Reason: Nuclear localization is shown experimentally for BEH2 (CFP-BEH2 in tobacco; BEH2-GFP in onion and Arabidopsis roots), and it is where its TF activity acts. BEH2 appearing in its own With/From reflects its own experimental grounding. Supporting Evidence: PMID:20128883 The fluorescence signals for the CFP-tagged transcription factors BES1, BZR1 and BEH2 were found in the nucleus. PMID:35695417 Together, the results indicate that, unlike BZR1, BEH2 proteins are consistently localized in the nucleus and not modulated by a nuclear-cytoplasmic shuttling mechanism depending on BR levels. |
| GO:0005634 nucleus | IDA PMID:37926922 Comparative analysis of BZR1/BES1 family transcription facto... | ACCEPT | Summary: IDA nucleus from Kim et al. 2024 (fluorescent-protein localization of family members). Reason: The abstract states BEH1 and BEH2 are predominantly nuclear; this is corroborated by full-text data in two other papers (PMID:20128883, PMID:35695417). Nucleus is the site of its TF function. Supporting Evidence: PMID:37926922 Notably, BEH1 and BEH2 are predominantly localized in the nucleus PMID:35695417 Together, the results indicate that, unlike BZR1, BEH2 proteins are consistently localized in the nucleus and not modulated by a nuclear-cytoplasmic shuttling mechanism depending on BR levels. PMID:20128883 The fluorescence signals for the CFP-tagged transcription factors BES1, BZR1 and BEH2 were found in the nucleus. |
| GO:0005634 nucleus | ISM GO_REF:0000122 | ACCEPT | Summary: AtSubP sequence-based prediction of nuclear localization. Reason: Prediction agrees with experimental localization; BEH2 also has a putative bipartite NLS noted by Otani et al. Supporting Evidence: PMID:35695417 Together, the results indicate that, unlike BZR1, BEH2 proteins are consistently localized in the nucleus and not modulated by a nuclear-cytoplasmic shuttling mechanism depending on BR levels. |
| GO:0006351 DNA-templated transcription | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO mapping of IPR033264 to DNA-templated transcription. Reason: BEH2 is a sequence-specific transcription factor: it regulates transcription of target genes rather than executing RNA synthesis. The role captured by the evidence is regulation of DNA-templated transcription (GO:0006355), which BEH2 already carries by IBA/IEA/TAS; this is a lateral correction, not a refinement to a descendant. Proposed replacements: regulation of DNA-templated transcription Supporting Evidence: PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression PMID:35695417 However, we can still claim that BEH2 can potentially regulate over a thousand genes directly or indirectly. |
| GO:0006355 regulation of DNA-templated transcription | IBA GO_REF:0000033 | ACCEPT | Summary: IBA regulation of DNA-templated transcription from the BZR family node. Reason: Consistent with the TF activity of the family and with BEH2 overexpression altering expression of >1000 genes. Direction (activation vs repression) is not established for BEH2, so the parent regulation term is appropriate. Supporting Evidence: PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression PMID:35695417 However, we can still claim that BEH2 can potentially regulate over a thousand genes directly or indirectly. |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-derived regulation of DNA-templated transcription. Reason: Same claim as the IBA row and supported by BEH2 overexpression transcriptomics; kept for consistency. Supporting Evidence: PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression |
| GO:0006355 regulation of DNA-templated transcription | TAS PMID:11970900 Nuclear-localized BZR1 mediates brassinosteroid-induced grow... | ACCEPT | Summary: TAS (acts_upstream_of_or_within) regulation of DNA-templated transcription citing Wang et al. 2002 (BZR1). Reason: The cited paper (abstract-only in cache) is about BZR1, and BEH2 is presumably mentioned in the full text as a family homolog; the statement that BEH2 regulates transcription is independently supported by BEH2 transcriptomic data and domain/family membership. Deferring to the TAIR curator on the reference choice. Supporting Evidence: PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression PMID:35695417 However, we can still claim that BEH2 can potentially regulate over a thousand genes directly or indirectly. |
| GO:0009742 brassinosteroid mediated signaling pathway | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO mapping of BZR family to brassinosteroid mediated signaling pathway. Reason: BEH2 is a terminal transcriptional effector of BR signalling, like BZR1/BES1: it is phosphorylated directly by BR-regulated GSK3-like kinases (ASKtheta, BIN2-interacting), dephosphorylated in response to BR, the P222L (BEH2m) stabilizing mutation gives a constitutive BR response, and its overexpression rescues bri1-5 and drives BR-responsive gene expression. As the DNA-binding output of the pathway BEH2 performs the transcriptional step of the signalling pathway rather than merely being required for it. Supporting Evidence: PMID:20128883 GST-ASKΞΈ phosphorylated GST-BZR1, GST-BES1 and GST-BEH2, but not GST alone (Figure 5). file:ARATH/BEH2/BEH2-uniprot.txt P->L: In BEH2m; increased stability of the protein and constitutive brassinosteroids response. PMID:37926922 Unexpectedly, BEH2-overexpressing plants showed the most distinct phenotype with enhanced BR responses. PMID:37926922 RNA-Seq analysis indicated that overexpression of both BZR1 and BEH2 regulates BR-responsive gene expression |
| GO:0046982 protein heterodimerization activity | IPI PMID:37926922 Comparative analysis of BZR1/BES1 family transcription facto... | NEW | Summary: Proposed: BEH2 heterodimerizes with other BZR1/BES1-family transcription factors. Reason: Kim et al. 2024 report that the constitutively nuclear BEH1 and BEH2 drive nuclear accumulation of other BZR1/BES1 family members through heterodimerization. This is a more informative replacement for the generic protein-binding rows and describes BEH2 own activity (it is one partner of the dimer). Kept non-core because partner identity and in vivo relevance are only described in the abstract available here. Supporting Evidence: PMID:37926922 which induces the nuclear accumulation of other BZR1/BES1 family proteins through heterodimerization |
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Download this section (compressed HTML)Q: Does BEH2 bind BRRE and E-box elements directly, and does it act predominantly as an activator or repressor of its targets?
Q: How does the constitutive nuclear localization of BEH2 (despite a conserved 14-3-3 site) affect nuclear retention of BZR1/BES1 heterodimer partners in planta?
Q: Is the AT3G61140 (CSN1) With/From partner in the TAIR IPI row for PMID:37926922 an error for AT3G61160 (ASK-beta)?
Experiment: EMSA and ChIP-seq of BEH2 (wild type and BEH2m) to define direct targets and binding motifs, compared with BZR1/BES1.
Experiment: CRISPR null alleles of BEH2 in combination with the qui-1 quintuple mutant to test whether BEH2 contributes to the residual BR/anther phenotypes of the family.
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