Two E3 ligases antagonistically regulate the UV-B response in
            <i>Arabidopsis</i>

Ren, Hai; Han, Jiupan; Yang, Po; Mao, Weiwei; Liu, Xin; Qiu, Leilei; Qian, Changli; Liu, Yan; Chen, Zhiren; Ouyang, Xinhao; Chen, Xu; Deng, Xing Wang; Huang, Xi

doi:10.1073/pnas.1816268116

Cited by 73 publications

(51 citation statements)

References 39 publications

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“…The transcript levels of CHS, UGT84A, ELIP1, and ELIP2 were up-regulated in double-mutant rup1-1 rup2-1 seedlings. Meanwhile, COP1 directly targets RUP1/RUP2 for degradation, which alleviates RUP1/RUP2 accumulation and COP1-HY5, thus stabilizing HY5 under UV-B radiation [35]. The accumulation of anthocyanin in three myb mutants was higher than that in hy5 mutants, indicating that the accumulation of anthocyanin must require the accumulation of HY5 [36].…”

Section: The Accumulation Of Flavonoids and Anthocyanins Under Uv-b Rmentioning

confidence: 98%

Quantitative Proteomic Analyses Identify STO/BBX24 -Related Proteins Induced by UV-B

Lyu

Xiong

et al. 2020

IJMS

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Plants use solar radiation for photosynthesis and are inevitably exposed to UV-B. To adapt to UV-B radiation, plants have evolved a sophisticated strategy, but the mechanism is not well understood. We have previously reported that STO (salt tolerance)/BBX24 is a negative regulator of UV-B-induced photomorphogenesis. However, there is limited knowledge of the regulatory network of STO in UV-B signaling. Here, we report the identification of proteins differentially expressed in the wild type (WT) and sto mutant after UV-B radiation by iTRAQ (isobaric tags for relative and absolute quantitation)-based proteomic analysis to explore differential proteins that depend on STO and UV-B signaling. A total of 8212 proteins were successfully identified, 221 of them were STO-dependent proteins in UV-B irradiated plants. The abundances of STO-dependent PSB and LHC (light-harvesting complex) proteins in sto mutants decreased under UV-B radiation, suggesting that STO is necessary to maintain the normal accumulation of photosynthetic system complex under UV-B radiation to facilitate photosynthesis photon capture. The abundance of phenylalanine lyase-1 (PAL1), chalcone synthetase (CHS), and flavonoid synthetase (FLS) increased significantly after UV-B irradiation, suggesting that the accumulation of flavonoids do not require STO, but UV-B is needed. Under UV-B radiation, STO stabilizes the structure of antenna protein complex by maintaining the accumulation of PSBs and LHCs, thereby enhancing the non-photochemical quenching (NPQ) ability, releasing extra energy, protecting photosynthesis, and ultimately promoting the elongation of hypocotyl. The accumulation of flavonoid synthesis key proteins is independent of STO under UV-B radiation. Overall, our results provide a comprehensive regulatory network of STO in UV-B signaling.

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Section: The Accumulation Of Flavonoids and Anthocyanins Under Uv-b Rmentioning

confidence: 98%

Quantitative Proteomic Analyses Identify STO/BBX24 -Related Proteins Induced by UV-B

Lyu

Xiong

et al. 2020

IJMS

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“…COP1 can also act as a substrate adaptor in CULLIN4–DAMAGED DNA BINDING PROTEIN 1 (CUL4‐DDB1)‐based heteromeric E3 ubiquitin ligase complexes (Chen et al , ). These different complexes may finetune COP1's activity toward different substrates (Ren et al , ). COP1 regulates gene expression and plays a central role as a repressor of photomorphogenesis by directly modulating the stability of transcription factors that control the expression of light‐regulated genes (Lau & Deng, ; Podolec & Ulm, ).…”

Section: Introductionmentioning

confidence: 99%

Plant photoreceptors and their signaling components compete for COP 1 binding via VP peptide motifs

et al. 2019

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Plants sense different parts of the sun's light spectrum using distinct photoreceptors, which signal through the E3 ubiquitin ligase COP1. Here, we analyze why many COP1‐interacting transcription factors and photoreceptors harbor sequence‐divergent Val‐Pro (VP) motifs that bind COP1 with different binding affinities. Crystal structures of the VP motifs of the UV‐B photoreceptor UVR8 and the transcription factor HY5 in complex with COP1, quantitative binding assays, and reverse genetic experiments together suggest that UVR8 and HY5 compete for COP1. Photoactivation of UVR8 leads to high‐affinity cooperative binding of its VP motif and its photosensing core to COP1, preventing COP1 binding to its substrate HY5. UVR8–VP motif chimeras suggest that UV‐B signaling specificity resides in the UVR8 photoreceptor core. Different COP1–VP peptide motif complexes highlight sequence fingerprints required for COP1 targeting. The blue‐light photoreceptors CRY1 and CRY2 also compete with transcription factors for COP1 binding using similar VP motifs. Thus, our work reveals that different photoreceptors and their signaling components compete for COP1 via a conserved mechanism to control different light signaling cascades.

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“…The UV‐B‐mediated interaction of UVR8 and the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) induces stability of the HY5 protein and HY5 transcription, resulting in enrichment of HY5 at the promoters of UV‐B‐responsive genes (Favory et al , ; Huang et al , ; Binkert et al , ; Yin et al , ). The UVR8‐mediated inhibition of hypocotyl elongation is a UV‐B response commonly used to identify and characterize positive and negative regulators of UV‐B perception and signaling (Oravecz et al , ; Favory et al , ; Gruber et al , ; Heijde et al , ; Huang et al , ; Huang et al , ; Liang et al , ; Yang et al , ; Ren et al , ; Yadav et al , ). Despite this broad use as a UVR8 signaling readout, the mechanisms by which UVR8 triggers inhibition of hypocotyl growth have only recently begun to be elucidated.…”

Section: Introductionmentioning

confidence: 99%

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

2019

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Summary Inhibition of hypocotyl growth is a well‐established UV‐B‐induced photomorphogenic response that is mediated by the UV‐B photoreceptor UV RESISTANCE LOCUS 8 (UVR8). However, the molecular mechanism by which UVR8 signaling triggers inhibition of hypocotyl growth is poorly understood. The bZIP protein ELONGATED HYPOCOTYL 5 (HY5) functions as the main positive regulatory transcription factor in the UVR8 signaling pathway, with HY5‐HOMOLOG (HYH) playing a minor role. However, here we demonstrate that hy5 hyh double mutants maintain significant UVR8‐dependent hypocotyl growth inhibition. We identify UVR8‐dependent inhibition of the activities of bHLH transcription factors PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5 as part of the UVR8 signaling pathway, which results in inhibition of hypocotyl growth. The UVR8‐mediated repression of several hypocotyl elongation‐related genes is independent of HY5 and HYH but largely associated with UVR8‐dependent degradation of PIF4 and PIF5, a process that consequently diminishes PIF4/5 target promoter occupancy. Taken together, our data indicate that UVR8‐mediated inhibition of hypocotyl growth involves degradation of PIF4 and PIF5. These findings contribute to our mechanistic understanding of UVR8‐induced photomorphogenesis and further support the function of PIFs as integrators of different photoreceptor signaling pathways.

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Two E3 ligases antagonistically regulate the UV-B response in Arabidopsis

Cited by 73 publications

References 39 publications

Quantitative Proteomic Analyses Identify STO/BBX24 -Related Proteins Induced by UV-B

Quantitative Proteomic Analyses Identify STO/BBX24 -Related Proteins Induced by UV-B

Plant photoreceptors and their signaling components compete for COP 1 binding via VP peptide motifs

Degradation of the transcription factors PIF4 and PIF5 under UV‐B promotes UVR8‐mediated inhibition of hypocotyl growth in Arabidopsis

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