The C‐terminal 17 amino acids of the photoreceptor UVR8 is involved in the fine‐tuning of UV‐B signaling

Li, Lin; Dong, Huaxi; Yang, Guoqian; Yin, Ruohe

doi:10.1111/jipb.12977

Cited by 15 publications

(8 citation statements)

References 51 publications

(100 reference statements)

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“…In the UV‐B signaling pathway, COP1 is a critical partner of UVR8 (Favory et al., 2009; Oravecz et al., 2006; Yin et al., 2016). UVR8 interacts with COP1 in a UV‐B‐dependent manner (Favory et al., 2009; Rizzini et al., 2011) through its beta‐propeller core domain and the C27 domain, which contains a VP motif (Cloix et al., 2012; Lin et al., 2020; Wang et al., 2022; Wu et al., 2013; Yin et al., 2015). The UV‐B‐activated photoreceptor UVR8 interacts with COP1 with high affinity, leading to the displacement of HY5 from COP1 and its stabilization (Lau et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

Dissecting the functions of COP1 in the UVR8 pathway with a COP1 variant in Arabidopsis

Zhang

Fang

et al. 2022

The Plant Journal

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SUMMARY COP1 is a critical repressor of plant photomorphogenesis in darkness. However, COP1 plays distinct roles in the photoreceptor UVR8 pathway in Arabidopsis thaliana. COP1 interacts with ultraviolet B (UV‐B)‐activated UVR8 monomers and promotes their retention and accumulation in the nucleus. Moreover, COP1 has a function in UV‐B signaling, which involves the binding of its WD40 domain to UVR8 and HY5 via conserved Val‐Pro (VP) motifs of these proteins. UV‐B‐activated UVR8 interacts with COP1 via both the core domain and the VP motif, leading to the displacement of HY5 from COP1 and HY5 stabilization. However, it remains unclear whether the function of COP1 in UV‐B signaling is solely dependent on its VP motif binding capacity and whether UV‐B regulates the subcellular localization of COP1. Based on published structures of the COP1 WD40 domain, we generated a COP1 variant with a single amino acid substitution, COP1C509S, which cannot bind to VP motifs but retains the ability to interact with the UVR8 core domain. UV‐B only marginally increased nuclear YFP‐COP1 levels and significantly promoted YFP‐COP1 accumulation in the cytosol, but did not exert the same effects on YFP‐COP1C509S. Thus, the full UVR8–COP1 interaction is important for COP1 accumulation in the cytosol. Notably, UV‐B signaling including activation of HY5 transcription was obviously inhibited in the Arabidopsis lines expressing YFP‐COP1C509S, which cannot bind VP motifs. We conclude that the full binding of UVR8 to COP1 leads to the predominant accumulation of COP1 in the cytosol and that COP1 has an additional function in UV‐B signaling besides VP binding‐mediated protein destabilization.

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Section: Introductionmentioning

confidence: 99%

Dissecting the functions of COP1 in the UVR8 pathway with a COP1 variant in Arabidopsis

Zhang

Fang

et al. 2022

The Plant Journal

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“…The interaction of the C27 domain in the C-terminal tail of UVR8 with the WD40 domain of COP1 is critical for UV-B signaling. Lin et al (2020) report an inhibitory role for UVR8 C17 in fine-tuning UVR8-COP1 interactions during U2020V-B signaling. They established that Arabidopsis UVR8 C17 binds to full-length UVR8, but not to COP1, and reduces COP1 binding to the remaining portion of UVR8, including C27.…”

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confidence: 85%

Photobiology: Light signal transduction and photomorphogenesis

Liu

Lin

Deng

2020

JIPB

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“…Arabidopsis and tomato seeds were surface‐sterilized and sown on half‐strength Murashige & Skoog basal salt medium (MS; Duchefa Biochemie, Haarlem, the Netherlands) containing 1% (w/v) sucrose and 1% (w/v) agar (pH = 5.8). The seeds were stratified for 2 d in the dark at 4°C and transferred to a growth chamber with continuous white light (3.6 μmol m −2 s −1 ; –UV‐B) or white light supplemented with photomorphogenic UV‐B (TL20W/01RS; Philips, Hamburg, Germany; 1.5 μmol m −2 s −1 ) for the indicated periods (Oravecz et al ., 2006 ; Lin et al ., 2020 ). Broadband UV‐B treatment was performed with a Philips TL40W/12RS to enhance UVR8 monomerization rapidly as reported previously (Rizzini et al ., 2011 ; Lin et al ., 2020 ).…”

Section: Methodsmentioning

confidence: 99%

“…CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), a repressor of plant photomorphogenesis (Yi & Deng, 2005 ; Han et al ., 2019 ), is a key player of UVR8‐mediated UV‐B signaling (Oravecz et al ., 2006 ). CONSTITUTIVELY PHOTOMORPHOGENIC 1 interacts with UVR8 in a UV‐B‐dependent manner (Favory et al ., 2009 ; Rizzini et al ., 2011 ), via two domains in UVR8, the core domain (Crefcoeur et al ., 2013 ; Yin et al ., 2015 ) and a well‐conserved C27 domain located within the C‐terminus (Cloix et al ., 2012 ; Yin et al ., 2015 ; Lin et al ., 2020 ). Interestingly, RUP1 and RUP2 also interact with UVR8 via the C27 domain (Cloix et al ., 2012 ; Yin et al ., 2015 ), suggesting that COP1 and RUP1/2 may compete for UVR8 binding.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of UV‐B light‐induced photoreceptor UVR8 nuclear localization dynamics

Fang

Zhang

et al. 2022

New Phytologist

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Summary Light regulates the subcellular localization of plant photoreceptors, a key step in light signaling. Ultraviolet‐B radiation (UV‐B) induces the plant photoreceptor UV RESISTANCE LOCUS 8 (UVR8) nuclear accumulation, where it regulates photomorphogenesis. However, the molecular mechanism for the UV‐B‐regulated UVR8 nuclear localization dynamics is unknown. With fluorescence recovery after photobleaching (FRAP), cell fractionation followed by immunoblotting and co‐immunoprecipitation (Co‐IP) assays we tested the function of UVR8‐interacting proteins including CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), REPRESSOR OF UV‐B PHOTOMORPHOGENESIS 1 (RUP1) and RUP2 in the regulation of UVR8 nuclear dynamics in Arabidopsis thaliana. We showed that UV‐B‐induced rapid UVR8 nuclear translocation is independent of COP1, which previously was shown to be required for UV‐B‐induced UVR8 nuclear accumulation. Instead, we provide evidence that the UV‐B‐induced UVR8 homodimer‐to‐monomer photo‐switch and the concurrent size reduction of UVR8 enables its monomer nuclear translocation, most likely via free diffusion. Nuclear COP1 interacts with UV‐B‐activated UVR8 monomer, thereby promoting UVR8 nuclear retention. Conversely, RUP1and RUP2, whose expressions are induced by UV‐B, inhibit UVR8 nuclear retention via attenuating the UVR8–COP1 interaction, allowing UVR8 to exit the nucleus. Collectively, our data suggest that UV‐B‐induced monomerization of UVR8 promotes its nuclear translocation via free diffusion. In the nucleus, COP1 binding promotes UVR8 monomer nuclear retention, which is counterbalanced by the major negative regulators RUP1 and RUP2.

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The C‐terminal 17 amino acids of the photoreceptor UVR8 is involved in the fine‐tuning of UV‐B signaling

Cited by 15 publications

References 51 publications

Dissecting the functions of COP1 in the UVR8 pathway with a COP1 variant in Arabidopsis

Dissecting the functions of COP1 in the UVR8 pathway with a COP1 variant in Arabidopsis

Photobiology: Light signal transduction and photomorphogenesis

Mechanisms of UV‐B light‐induced photoreceptor UVR8 nuclear localization dynamics

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