ELF4

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005634 nucleus	IBA GO_REF:0000033	ACCEPT	Summary: ELF4 nuclear localization is well-established. The Evening Complex (ELF4-ELF3-LUX) localizes to the nucleus where it binds target promoters and represses transcription [PMID:21753751, PMID:14605220, PMID:22327739]. UniProt also confirms nuclear localization with diffuse distribution, and targeting to nuclear bodies after interaction with ELF3. Reason: IBA annotation is consistent with extensive experimental evidence. Multiple IDA annotations confirm nuclear localization (PMID:21753751, PMID:14605220). The EC functions as a nuclear transcriptional repressor complex. Supporting Evidence: PMID:21753751 ELF3, LUX and ELF4-HA peaked at ZT12, declined during the night, reached a trough between ZT0-ZT4, and then increased again PMID:14605220 The locus encodes a novel protein that we show localizes to the nucleus, thus suggesting a function in light-regulated gene expression.
GO:0009649 entrainment of circadian clock	IBA GO_REF:0000033	ACCEPT	Summary: Entrainment of circadian clock is a core function of ELF4. McWatters et al. (2007) showed ELF4 is necessary for entrainment to environmental cycles [PMID:17384164]. The elf4 mutant demonstrates clock input defects and does not entrain normally. Reason: IBA annotation is well-supported by experimental evidence. ELF4 is explicitly required for entrainment, as demonstrated by IMP evidence in PMID:17384164. Supporting Evidence: PMID:17384164 Here, it is shown that ELF4 is necessary for at least two core clock functions: entrainment to an environmental cycle and rhythm sustainability under constant conditions.
GO:0005634 nucleus	IEA GO_REF:0000044	ACCEPT	Summary: IEA annotation based on UniProt subcellular location mapping. This is consistent with multiple experimental confirmations of nuclear localization. Reason: Redundant with IBA and IDA annotations but correctly mapped. Nuclear localization is well-established for ELF4. Supporting Evidence: PMID:14605220 The locus encodes a novel protein that we show localizes to the nucleus
GO:0009585 red, far-red light phototransduction	IEA GO_REF:0000043	MODIFY	Summary: This term is derived from UniProt keyword mapping. While ELF4 is involved in phytochrome signaling, particularly phyB-mediated responses, "phototransduction" typically refers to sensory transduction in photoreceptor cells. ELF4's role is more accurately described as involvement in the phytochrome signaling pathway downstream of light perception. Reason: "Phototransduction" is not the most accurate term. ELF4 functions in the phytochrome B signaling pathway but is not a phototransduction component per se. The term "red or far-red light signaling pathway" (GO:0010017) is already annotated with IMP evidence and is more appropriate. Proposed replacements: red or far-red light signaling pathway Supporting Evidence: PMID:14605220 Mutants at one such locus displayed reduced responsiveness to continuous red, but not continuous far-red light, suggesting a role in phyB signaling but not phyA signaling.
GO:0009908 flower development	IEA GO_REF:0000043	MODIFY	Summary: This annotation is derived from the UniProt "Flowering" keyword. While ELF4 affects flowering time (elf4 mutants flower early), ELF4 does not directly participate in flower development/organogenesis. Rather, ELF4 regulates the timing of the floral transition through its role in the circadian clock and photoperiodism. The appropriate terms are "regulation of flower development" or "photoperiodism, flowering". Reason: ELF4 regulates flowering TIME, not flower development per se. The gene affects when flowering occurs, not the developmental process of flower formation. "Regulation of flower development" (GO:0009909) is already annotated with IMP evidence and is more accurate. Proposed replacements: regulation of flower development Supporting Evidence: PMID:12214234 Mutations in elf4 result in early flowering in non-inductive photoperiods, which is probably caused by elevated amounts of CONSTANS (CO), a gene that promotes floral induction.
GO:0010017 red or far-red light signaling pathway	IEA GO_REF:0000043	ACCEPT	Summary: ELF4 is involved in phytochrome B-mediated red light signaling. Khanna et al. (2003) showed elf4 mutants have reduced responsiveness to continuous red light [PMID:14605220]. This IEA annotation is consistent with IMP evidence. Reason: This annotation is supported by experimental evidence (IMP from PMID:16891401). ELF4 functions in phyB signaling pathway during seedling de-etiolation. Supporting Evidence: PMID:14605220 Mutants at one such locus displayed reduced responsiveness to continuous red, but not continuous far-red light, suggesting a role in phyB signaling but not phyA signaling.
GO:0042753 positive regulation of circadian rhythm	IEA GO_REF:0000002	ACCEPT	Summary: ELF4 promotes clock accuracy and sustained rhythms. Loss of ELF4 leads to arrhythmicity, demonstrating it positively regulates circadian rhythm. This IEA annotation from InterPro mapping is consistent with multiple IMP annotations. Reason: This is a core function of ELF4. Multiple experimental studies confirm ELF4 promotes circadian rhythm maintenance [PMID:12214234, PMID:20357892]. Supporting Evidence: PMID:12214234 ELF4 promotes clock accuracy and is required for sustained rhythms in the absence of daily light/dark cycles.
GO:0048511 rhythmic process	IEA GO_REF:0000043	MARK AS OVER ANNOTATED	Summary: This annotation is derived from the UniProt "Biological rhythms" keyword. While technically correct, this is a very broad parent term. ELF4 has more specific annotations for circadian rhythm-related processes including "regulation of circadian rhythm" (GO:0042752), "positive regulation of circadian rhythm" (GO:0042753), and "entrainment of circadian clock" (GO:0009649). Reason: This term is redundant with more specific circadian terms already annotated. "Rhythmic process" (GO:0048511) is a parent of "circadian rhythm" (GO:0007623), which is in turn a parent of the more specific terms annotated for ELF4. While not incorrect, this general annotation adds no information beyond what is captured by the specific circadian annotations with experimental evidence. For a bona fide circadian clock component like ELF4, the specific terms are preferred. Supporting Evidence: PMID:12214234 ELF4 promotes clock accuracy and is required for sustained rhythms in the absence of daily light/dark cycles. elf4 mutants show attenuated expression of CIRCADIAN CLOCK ASSOCIATED 1 (CCA1), a gene that is thought to function as a central oscillator component.
GO:0005515 protein binding	IPI PMID:21753751 The ELF4-ELF3-LUX complex links the circadian clock to diurn...	MODIFY	Summary: Nusinow et al. (2011) demonstrated ELF4 interacts with ELF3 to form the Evening Complex. ELF4-HA co-immunoprecipitated both ELF3 and LUX. ELF3 bridges the interaction between ELF4 and LUX. Reason: "Protein binding" is too general and uninformative. This PMID:21753751 interaction evidence concerns ELF4 binding ELF3 and assembly of the ELF4-ELF3-LUX Evening Complex, not ELF4 homodimerization. Protein-containing complex binding better captures the evidence from this row, while ELF4 homodimerization remains supported separately by PMID:20357892. Proposed replacements: protein-containing complex binding Supporting Evidence: PMID:21753751 Using a yeast two-hybrid assay, we found that ELF4 interacted with ELF3 PMID:21753751 ELF3 is both necessary and sufficient to form a complex between ELF4 and LUX
GO:0000122 negative regulation of transcription by RNA polymerase II	IDA PMID:21236673 LUX ARRHYTHMO encodes a nighttime repressor of circadian gen...	ACCEPT	Summary: The Evening Complex (ELF4-ELF3-LUX) functions as a transcriptional repressor. LUX provides DNA-binding specificity while ELF3 and ELF4 are required for repression. The EC directly represses PRR9, PIF4, PIF5, and other targets. Reason: This is a core molecular function of the Evening Complex. ELF4 is an essential component of the EC transcriptional repressor. ChIP experiments confirmed ELF4 is present at target promoters [PMID:21753751]. Supporting Evidence: PMID:21753751 we performed similar ChIP experiments for ELF3 and ELF4-HA. We found that ELF3 and ELF4-HA showed specific enrichment at PIF4 and PIF5 promoter sequences that were also bound by LUX PMID:21236673 We also show that LUX binds to its own promoter, defining a new negative autoregulatory feedback loop within the core clock. file:ARATH/ELF4/ELF4-deep-research-falcon.md The EC (ELF3-ELF4-LUX) is a dusk-phased nuclear repressor complex central to the Arabidopsis circadian oscillator.
GO:0003714 transcription corepressor activity	IDA PMID:21753751 The ELF4-ELF3-LUX complex links the circadian clock to diurn...	NEW	Summary: ELF4 is an essential component of the ELF3-ELF4-LUX Evening Complex, which represses transcription of clock and growth target genes including PIF4 and PIF5. LUX supplies DNA-binding specificity, while ELF4 contributes to the repressive complex rather than acting as an independent DNA-binding factor. Reason: This molecular function captures ELF4's operative role in the Evening Complex better than generic protein binding or homodimerization. The direct evidence shows ELF4 in a promoter-associated repressor complex that reduces target-gene transcription. Supporting Evidence: PMID:21753751 Here we identify a protein complex (called the evening complex)--composed of the proteins encoded by EARLY FLOWERING 3 (ELF3), ELF4 and the transcription-factor-encoding gene LUX ARRHYTHMO (LUX; also known as PHYTOCLOCK 1)--that directly regulates plant growth PMID:21753751 ELF3 and ELF4-HA showed specific enrichment at PIF4 and PIF5 promoter sequences that were also bound by LUX file:ARATH/ELF4/ELF4-deep-research-falcon.md The EC (ELF3-ELF4-LUX) is a dusk-phased nuclear repressor complex central to the Arabidopsis circadian oscillator.
GO:0005634 nucleus	IDA PMID:21753751 The ELF4-ELF3-LUX complex links the circadian clock to diurn...	ACCEPT	Summary: Direct experimental evidence for nuclear localization from immunoprecipitation and ChIP experiments showing ELF4 at target gene promoters in the nucleus. Reason: Primary experimental evidence for nuclear localization. ELF4-HA was shown to co-immunoprecipitate nuclear proteins ELF3 and LUX, and ChIP showed ELF4 at target promoters. Supporting Evidence: PMID:21753751 We found that ELF4-HA could co-immunoprecipitate both ELF3 and LUX
GO:0042752 regulation of circadian rhythm	IDA PMID:21753751 The ELF4-ELF3-LUX complex links the circadian clock to diurn...	ACCEPT	Summary: ELF4 is a core component of the circadian clock as part of the Evening Complex. The EC regulates expression of clock genes and outputs. Loss of ELF4 results in arrhythmicity. Reason: Core function of ELF4. As part of the Evening Complex, ELF4 directly participates in circadian clock regulation through transcriptional repression of clock genes. Supporting Evidence: PMID:21753751 elf3, elf4 and lux share multiple phenotypes, including an arrhythmic circadian oscillator PMID:17384164 ELF4, therefore, can be considered a component of the central CCA1/LHY-TOC1 feedback loop in the plant circadian clock.
GO:0005634 nucleus	ISM GO_REF:0000122	ACCEPT	Summary: ISM annotation from AtSubP analysis predicting subcellular localization. Consistent with experimental evidence. Reason: Computational prediction is confirmed by multiple experimental studies demonstrating nuclear localization of ELF4. Supporting Evidence: PMID:14605220 The locus encodes a novel protein that we show localizes to the nucleus
GO:0009648 photoperiodism	IEP PMID:20357892 Integrating ELF4 into the circadian system through combined ...	ACCEPT	Summary: ELF4 expression follows a light-dependent circadian pattern with a peak in the evening, consistent with its role in photoperiodism. The EC is sensitive to photoperiod, with complex formation peaking earlier in short days compared to long days. Reason: ELF4's circadian-regulated expression pattern supports its role in photoperiodism. The gene is induced by light and its expression pattern is relevant to photoperiod sensing. Supporting Evidence: PMID:21753751 Complex formation was also sensitive to photoperiod, peaking earlier in short days compared to long days
GO:0042753 positive regulation of circadian rhythm	IMP PMID:20357892 Integrating ELF4 into the circadian system through combined ...	ACCEPT	Summary: Kolmos et al. (2009) characterized elf4 hypomorphic alleles and showed expression level phenotypes of both morning and evening clock genes, demonstrating ELF4's role in maintaining circadian oscillation. Reason: Primary experimental evidence showing ELF4 promotes circadian rhythm. Mutant phenotypes demonstrate ELF4 is required for proper circadian gene expression. Supporting Evidence: PMID:20357892 These weak mutants were found to have expression level phenotypes of both morning and evening clock genes, implicating multiple entry points of ELF4 within the multiloop network.
GO:0009649 entrainment of circadian clock	IMP PMID:17384164 ELF4 is required for oscillatory properties of the circadian...	ACCEPT	Summary: McWatters et al. (2007) demonstrated that ELF4 is necessary for entrainment to environmental cycles. elf4 mutants show increased light sensitivity and do not entrain normally to light/dark cycles. Reason: Core function of ELF4. Definitive experimental evidence that ELF4 is required for circadian clock entrainment. Supporting Evidence: PMID:17384164 Here, it is shown that ELF4 is necessary for at least two core clock functions: entrainment to an environmental cycle and rhythm sustainability under constant conditions. PMID:17384164 Rhythmicity in elf4 could be driven by an environmental cycle, but an increased sensitivity to light means the circadian system of elf4 plants does not entrain normally.
GO:0042803 protein homodimerization activity	IDA PMID:20357892 Integrating ELF4 into the circadian system through combined ...	ACCEPT	Summary: Kolmos et al. (2009) showed ELF4 forms an alpha-helical homodimer with a likely electrostatic interface. Multiple elf4 alleles with reduced homodimer stability showed impaired circadian function. Reason: Well-characterized molecular function. Homodimerization is important for ELF4 function, as mutations affecting dimer stability impair circadian regulation. Supporting Evidence: PMID:20357892 Here we show that ELF4 is functionally conserved within a subclade of related sequences, and forms an alpha-helical homodimer with a likely electrostatic interface that could be structurally modeled.
GO:0048573 photoperiodism, flowering	IMP PMID:18799658 Diversification of photoperiodic response patterns in a coll...	ACCEPT	Summary: Pouteau et al. (2008) studied photoperiodic response patterns in early-flowering mutants including elf4. The study characterized how clock mutants affect photoperiodic flowering responses. Reason: ELF4 is essential for proper photoperiodic flowering. elf4 mutants flower early in non-inductive photoperiods due to inability to properly measure day length. Supporting Evidence: PMID:18799658 A high proportion of mutants with altered Pce exhibited abnormal hypocotyl elongation in the dark and altered circadian periods of leaf movements. PMID:12214234 Mutations in elf4 result in early flowering in non-inductive photoperiods
GO:0010017 red or far-red light signaling pathway	IMP PMID:16891401 Functional profiling reveals that only a small number of phy...	ACCEPT	Summary: Khanna et al. (2006) showed elf4 mutants display reciprocal aberrant photoresponsiveness in hypocotyl and cotyledon growth, indicating disruption of phytochrome-regulated deetiolation. Reason: Experimental evidence for ELF4 function in phytochrome signaling. elf4 is one of only 7 genes (out of 32 tested) that showed significant deetiolation defects. Supporting Evidence: PMID:16891401 Seven (22%) lines displayed statistically significant, reciprocal, aberrant photoresponsiveness in the two organs, suggesting disruption of normal deetiolation PMID:14605220 suggesting a role in phyB signaling but not phyA signaling
GO:0005634 nucleus	IDA PMID:14605220 EARLY FLOWERING 4 functions in phytochrome B-regulated seedl...	ACCEPT	Summary: Khanna et al. (2003) showed ELF4 localizes to the nucleus using fluorescent protein fusion, suggesting a function in light-regulated gene expression. Reason: Primary experimental evidence for nuclear localization. This was one of the first demonstrations that ELF4 is a nuclear protein. Supporting Evidence: PMID:14605220 The locus encodes a novel protein that we show localizes to the nucleus, thus suggesting a function in light-regulated gene expression.
GO:0010114 response to red light	IMP PMID:14605220 EARLY FLOWERING 4 functions in phytochrome B-regulated seedl...	ACCEPT	Summary: elf4 mutants show reduced responsiveness to continuous red light, with hyposensitivity in hypocotyl inhibition. ELF4 expression is induced by red light via phyB signaling. Reason: Well-documented function. ELF4 is required for proper response to red light during seedling de-etiolation. Supporting Evidence: PMID:14605220 Mutants at one such locus displayed reduced responsiveness to continuous red, but not continuous far-red light, suggesting a role in phyB signaling but not phyA signaling. PMID:14605220 Consistent with such a role, expression of this gene is induced by continuous red light in wild-type seedlings, but the level of induction is strongly reduced in phyB-null mutants.
GO:0009909 regulation of flower development	IMP PMID:12214234 The ELF4 gene controls circadian rhythms and flowering time ...	ACCEPT	Summary: Doyle et al. (2002) showed elf4 mutants flower early in non-inductive photoperiods due to elevated CONSTANS (CO) expression. ELF4 is a negative regulator of flowering time. Reason: Valid downstream photoperiodic flowering output of ELF4's circadian/Evening Complex role. This should be kept, but it is not the primary molecular function of ELF4; the core function is EC-mediated transcriptional repression and clock regulation. Supporting Evidence: PMID:12214234 Mutations in elf4 result in early flowering in non-inductive photoperiods, which is probably caused by elevated amounts of CONSTANS (CO), a gene that promotes floral induction.
GO:0009648 photoperiodism	IMP PMID:12214234 The ELF4 gene controls circadian rhythms and flowering time ...	ACCEPT	Summary: Doyle et al. (2002) described ELF4's role in photoperiod perception. elf4 mutants are impaired in their ability to sense day length. Reason: Core function of ELF4. As a component of the circadian clock, ELF4 is essential for photoperiod measurement and response. Supporting Evidence: PMID:12214234 Here we describe the gene EARLY FLOWERING 4 (ELF4), which is involved in photoperiod perception and circadian regulation.
GO:0042753 positive regulation of circadian rhythm	IMP PMID:12214234 The ELF4 gene controls circadian rhythms and flowering time ...	ACCEPT	Summary: The founding paper on ELF4 by Doyle et al. (2002) established that ELF4 promotes clock accuracy and is required for sustained rhythms. Reason: Primary experimental evidence from the gene's discovery paper. ELF4 is required for circadian rhythm maintenance. Supporting Evidence: PMID:12214234 ELF4 promotes clock accuracy and is required for sustained rhythms in the absence of daily light/dark cycles. PMID:12214234 elf4 plants transiently show output rhythms with highly variable period lengths before becoming arrhythmic.
GO:0005667 transcription regulator complex	IDA PMID:21753751 The ELF4-ELF3-LUX complex links the circadian clock to diurn...	NEW	Summary: ELF4 is a component of the Evening Complex (EC), a tripartite transcriptional repressor complex. This is documented in ComplexPortal (CPX-1291) and demonstrated experimentally by co-immunoprecipitation and ChIP experiments. Reason: This annotation captures ELF4's role as part of the Evening Complex, which is central to its function. The EC is a well-characterized transcription regulator complex that represses target genes. Supporting Evidence: PMID:21753751 Here we identify a protein complex (called the evening complex)--composed of the proteins encoded by EARLY FLOWERING 3 (ELF3), ELF4 and the transcription-factor-encoding gene LUX ARRHYTHMO (LUX; also known as PHYTOCLOCK 1)--that directly regulates plant growth PMID:21753751 We found that ELF4-HA could co-immunoprecipitate both ELF3 and LUX

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