bHLH class transcription factors take centre stage in phytochrome signalling

Duek, Paula D.; Fankhauser, Christian

doi:10.1016/j.tplants.2004.12.005

Cited by 225 publications

(172 citation statements)

References 26 publications

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“…The proteins examined here may also be redundant in function with each other or with other untested proteins. In partial support of these predictions, FHY3 and FAR1 are closely related in sequence (Hudson et al, 1999;Wang and Deng, 2002b), HFR1 is a member of the bHLH family known to contain many members (such as the PIFs) with roles in phytochrome signaling (Duek and Fankhauser, 2005), and PAT1 shares high sequence similarity with several members of the GRAS protein family (Bolle et al, 2000). Finally, despite being a less likely scenario, the possibility that phyA regulates PEX11b partially through its cytoplasmically localized protein pool cannot be completely excluded.…”

Section: Discussionmentioning

confidence: 94%

Light Induces Peroxisome Proliferation in Arabidopsis Seedlings through the Photoreceptor Phytochrome A, the Transcription Factor HY5 HOMOLOG, and the Peroxisomal Protein PEROXIN11b

Desai

2008

Plant Physiology

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Peroxisomes are single membrane-delimited subcellular organelles that carry out numerous vital metabolic reactions in nearly all eukaryotes. Peroxisomes alter their morphology, abundance, and enzymatic constituents in response to environmental cues, yet little is known about the underlying mechanisms. In this work, we investigated the regulatory role of light in peroxisome proliferation in Arabidopsis (Arabidopsis thaliana). We provide evidence that light induces proliferation of peroxisomes in Arabidopsis seedlings and that the peroxisomal protein PEX11b plays an important role in mediating this process. The far-red light receptor phytochrome A (phyA) and the bZIP transcription factor HY5 HOMOLOG (HYH) are both required for the up-regulation of PEX11b in the light. We further demonstrate that the phyA and hyh mutants exhibit reduced peroxisome abundance, a phenotype that can be rescued by overexpressing PEX11b in these plants. The HYH protein is able to bind to the promoter of PEX11b, suggesting that the PEX11b gene is a direct target of HYH. We conclude that HYH and PEX11b constitute a novel branch of the phyA-mediated light signaling cascade, which promotes peroxisome proliferation during seedling photomorphogenesis.

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Section: Discussionmentioning

confidence: 94%

Light Induces Peroxisome Proliferation in Arabidopsis Seedlings through the Photoreceptor Phytochrome A, the Transcription Factor HY5 HOMOLOG, and the Peroxisomal Protein PEROXIN11b

Desai

2008

Plant Physiology

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“…Somewhat surprisingly, most PIF proteins act as negative regulators of the phyB pathway, leading to questions regarding the function of the PIF-phy interaction (Duek and Fankhauser, 2005). It has been proposed that the interaction of phyB with PIF4 is essential for the function of this transcription factor (Khanna et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Phytochrome‐mediated inhibition of shade avoidance involves degradation of growth‐promoting bHLH transcription factors

Lorrain¹,

Allen²,

Duek³

et al. 2007

The Plant Journal

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669

848

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SummaryPlant growth and development are particularly sensitive to changes in the light environment and especially to vegetational shading. The shade-avoidance response is mainly controlled by the phytochrome photoreceptors. In Arabidopsis, recent studies have identified several related bHLH class transcription factors (PIF, for phytochrome-interacting factors) as important components in phytochrome signaling. In addition to a related bHLH domain, most of the PIFs contain an active phytochrome binding (APB) domain that mediates their interaction with light-activated phytochrome B (phyB). Here we show that PIF4 and PIF5 act early in the phytochrome signaling pathways to promote the shade-avoidance response. PIF4 and PIF5 accumulate to high levels in the dark, are selectively degraded in response to red light, and remain at high levels under shademimicking conditions. Degradation of these transcription factors is preceded by phosphorylation, requires the APB domain and is sensitive to inhibitors of the proteasome, suggesting that PIF4 and PIF5 are degraded upon interaction with light-activated phyB. Our data suggest that, in dense vegetation, which is rich in far-red light, shade avoidance is triggered, at least partially, as a consequence of reduced phytochrome-mediated degradation of transcription factors such as PIF4 and PIF5. Consistent with this idea, the constitutive shadeavoidance phenotype of phyB mutants partially reverts in the absence of PIF4 and PIF5.

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“…Upon light absorption, a conformation shift to the far-red light-absorbing biologically active Pfr form triggers their nuclear translocation and photobody (speckle) formation (Nagatani, 2004;Chen and Chory, 2011). Within the nucleus, the activated Pfr physically interacts with multiple proteins, including a small group of basic helix-loop-helix (bHLH) transcription factors called Phytochrome Interacting Factors (PIFs; PIF1 and PIF3 to PIF8) (Quail, 2000;Quail, 2002, 2005;Huq et al, 2004;Duek and Fankhauser, 2005;M. Chen et al, 2010;Galvão et al, 2012;Paik et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

PHYTOCHROME INTERACTING FACTOR1 Enhances the E3 Ligase Activity of CONSTITUTIVE PHOTOMORPHOGENIC1 to Synergistically Repress Photomorphogenesis in Arabidopsis

Paik

Zhu

et al. 2014

The Plant Cell

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CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is a RING/WD40 repeat-containing ubiquitin E3 ligase that is conserved from plants to humans. COP1 forms complexes with SUPPRESSOR OF PHYTOCHROME A (SPA) proteins, and these complexes degrade positively acting transcription factors in the dark to repress photomorphogenesis. Phytochrome-interacting basic helixloop-helix transcription factors (PIFs) also repress photomorphogenesis in the dark. In response to light, the phytochrome family of sensory photoreceptors simultaneously inactivates COP1-SPA complexes and induces the rapid degradation of PIFs to promote photomorphogenesis. However, the functional relationship between PIFs and COP1-SPA complexes is still unknown. Here, we present genetic evidence that the pif and cop1/spa Arabidopsis thaliana mutants synergistically promote photomorphogenesis in the dark. LONG HYPOCOTYL5 (HY5) is stabilized in the cop1 pif1, spa123 pif1, and pif double, triple, and quadruple mutants in the dark. Moreover, the hy5 mutant suppresses the constitutive photomorphogenic phenotypes of the pifq mutant in the dark. PIF1 forms complexes with COP1, HY5, and SPA1 and enhances the substrate recruitment and autoubiquitylation and transubiquitylation activities of COP1. These data uncover a novel function of PIFs as the potential cofactors of COP1 and provide a genetic and biochemical model of how PIFs and COP1-SPA complexes synergistically repress photomorphogenesis in the dark.

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bHLH class transcription factors take centre stage in phytochrome signalling

Cited by 225 publications

References 26 publications

Light Induces Peroxisome Proliferation in Arabidopsis Seedlings through the Photoreceptor Phytochrome A, the Transcription Factor HY5 HOMOLOG, and the Peroxisomal Protein PEROXIN11b

Light Induces Peroxisome Proliferation in Arabidopsis Seedlings through the Photoreceptor Phytochrome A, the Transcription Factor HY5 HOMOLOG, and the Peroxisomal Protein PEROXIN11b

Phytochrome‐mediated inhibition of shade avoidance involves degradation of growth‐promoting bHLH transcription factors

PHYTOCHROME INTERACTING FACTOR1 Enhances the E3 Ligase Activity of CONSTITUTIVE PHOTOMORPHOGENIC1 to Synergistically Repress Photomorphogenesis in Arabidopsis

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