UV‐B Action Spectrum for UVR8‐Mediated <i>HY5</i> Transcript Accumulation in Arabidopsis

Brown, Bobby A.; Headland, Lauren R.; Jenkins, Gareth I.

doi:10.1111/j.1751-1097.2009.00579.x

Cited by 63 publications

(70 citation statements)

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“…HY5 is the major transcription factor required downstream of UVR8. In addition, the HY5 gene is an excellent and widely used marker for UVR8-mediated gene expression changes (Ulm et al, 2004;Brown et al, 2005Brown et al, , 2009Oravecz et al, 2006;Gruber et al, 2010;Huang et al, 2012;Jiang et al, 2012). Thus, it is thought that HY5 is required for UV-Bresponsive gene activation and that its own transcriptional induction as well as posttranslational stabilization further enforce the UV-B response Tilbrook et al, 2013;Jenkins, 2014).…”

Section: Discussionmentioning

confidence: 99%

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

et al. 2014

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In plants subjected to UV-B radiation, responses are activated that minimize damage caused by UV-B. The bZIP transcription factor ELONGATED HYPOCOTYL5 (HY5) acts downstream of the UV-B photoreceptor UV RESISTANCE LOCUS8 (UVR8) and promotes UV-B-induced photomorphogenesis and acclimation. Expression of HY5 is induced by UV-B; however, the transcription factor(s) that regulate HY5 transcription in response to UV-B and the impact of UV-B on the association of HY5 with its target promoters are currently unclear. Here, we show that HY5 binding to the promoters of UV-B-responsive genes is enhanced by UV-B in a UVR8-dependent manner in Arabidopsis thaliana. In agreement, overexpression of REPRESSOR OF UV-B PHOTOMORPHOGENESIS2, a negative regulator of UVR8 function, blocks UV-B-responsive HY5 enrichment at target promoters. Moreover, we have identified a T/G-box in the HY5 promoter that is required for its UV-B responsiveness. We show that HY5 and its homolog HYH bind to the T/G HY5 -box cis-acting element and that they act redundantly in the induction of HY5 expression upon UV-B exposure. Therefore, HY5 is enriched at target promoters in response to UV-B in a UVR8 photoreceptor-dependent manner, and HY5 and HYH interact directly with a T/G-box cis-acting element of the HY5 promoter, mediating the transcriptional activation of HY5 in response to UV-B.

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Section: Discussionmentioning

confidence: 99%

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

et al. 2014

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“…UVR8-and COP1-dependent UV-B induction of HY5 transcript and protein level has since been demonstrated numerous times (Brown et al 2005, Oravecz et al 2006, Kaiserli and Jenkins 2007, Brown et al 2009, Favory et al 2009). Interestingly, UVR8 itself is proposed to associate with chromatin in the vicinity of the HY5 genomic locus (Brown et al 2005, Cloix andJenkins 2008).…”

Section: The Bzip Transcription Factor Hy5 and Its Homologue Hyhmentioning

confidence: 99%

The UVR8 UV-B Photoreceptor: Perception, Signaling and Response

Tilbrook

Arongaus

Binkert

et al. 2013

The Arabidopsis Book

230

187

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Ultraviolet-B radiation (UV-B)is an intrinsic part of sunlight that is accompanied by significant biological effects. Plants are able to perceive UV-B using the UV-B photoreceptor UVR8 which is linked to a specific molecular signaling pathway and leads to UV-B acclimation. Herein we review the biological process in plants from initial UV-B perception and signal transduction through to the known UV-B responses that promote survival in sunlight. The UVR8 UV-B photoreceptor exists as a homodimer that instantly monomerises upon UV-B absorption via specific intrinsic tryptophans which act as UV-B chromophores. The UVR8 monomer interacts with COP1, an E3 ubiquitin ligase, initiating a molecular signaling pathway that leads to gene expression changes. This signaling output leads to UVR8-dependent responses including UV-B-induced photomorphogenesis and the accumulation of UV-B-absorbing flavonols. Negative feedback regulation of the pathway is provided by the WD40-repeat proteins RUP1 and RUP2, which facilitate UVR8 redimerization, disrupting the UVR8-COP1 interaction. Despite rapid advancements in the field of recent years, further components of UVR8 UV-B signaling are constantly emerging, and the precise interplay of these and the established players UVR8, COP1, RUP1, RUP2 and HY5 needs to be defined. UVR8 UV-B signaling represents our further understanding of how plants are able to sense their light environment and adjust their growth accordingly.

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“…An action spectrum of UVR8 function, derived from dose-response studies of the induction of HY5 transcripts indicates that UVR8 is most effective at 280 nm with significant action at 290 and 300 nm (Brown et al, 2009). Because 280 nm wavelengths do not reach the surface of the earth, the longer wavelength action of UVR8 is the most physiologically relevant.…”

Section: Introductionmentioning

confidence: 99%

In Vivo Function of Tryptophans in the Arabidopsis UV-B Photoreceptor UVR8

O’Hara

Jenkins

2012

The Plant Cell

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Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is a photoreceptor specifically for UV-B light that initiates photomorphogenic responses in plants. UV-B exposure causes rapid conversion of UVR8 from dimer to monomer, accumulation in the nucleus, and interaction with CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), which functions with UVR8 in UV-B responses. Studies in yeast and with purified UVR8 implicate several tryptophan amino acids in UV-B photoreception. However, their roles in UV-B responses in plants, and the functional significance of all 14 UVR8 tryptophans, are not known. Here we report the functions of the UVR8 tryptophans in vivo. Three tryptophans in the b-propeller core are important in maintaining structural stability and function of UVR8. However, mutation of three other core tryptophans and four at the dimeric interface has no apparent effect on function in vivo. Mutation of three tryptophans implicated in UV-B photoreception, W233, W285, and W337, impairs photomorphogenic responses to different extents. W285 is essential for UVR8 function in plants, whereas W233 is important but not essential for function, and W337 has a lesser role. Ala mutants of these tryptophans appear monomeric and constitutively bind COP1 in plants, but their responses indicate that monomer formation and COP1 binding are not sufficient for UVR8 function.

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UV‐B Action Spectrum for UVR8‐Mediated HY5 Transcript Accumulation in Arabidopsis

Cited by 63 publications

References 50 publications

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

UV-B-Responsive Association of the Arabidopsis bZIP Transcription Factor ELONGATED HYPOCOTYL5 with Target Genes, Including Its Own Promoter

The UVR8 UV-B Photoreceptor: Perception, Signaling and Response

In Vivo Function of Tryptophans in the Arabidopsis UV-B Photoreceptor UVR8

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