| Structural highlights
Function
UVR8_ARATH UV-B specific signaling component that acts as UV-B photoreceptor and plays a key role in establishing UV-protective responses in plants. Upon UV-B irradiation, UVR8 undergoes an immediate switch from homodimer to monomer, accumulates in the nucleus, interacts with the photomorphogenic repressor COP1 and regulates the expression of the transcription factor HY5 by associating with chromatin (through histone H2B binding) in the HY5 promoter region. UVR8 is involved in controlling aspects of leaf growth and morphogenesis in response to UV-B, is required for normal progression of endocycle and has a regulatory role in stomatal differentiation. Is required for plant circadian clock response to photomorphogenic UV-B light, partly through the transcriptional activation of responsive clock genes. Promotes photosynthetic efficiency at elevated levels of UV-B. Plays a role in mediating the effects of UV-B radiation on pathogen resistance by controlling the expression of the sinapate biosynthetic pathway. The two tryptophans, Trp-285 and Trp-233, serve collectively as the UV-B chromophore.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Publication Abstract from PubMed
The plant ultraviolet-B (UV-B) photoreceptor UVR8 plays an important role in UV-B acclimation and survival. UV-B absorption by homodimeric UVR8 induces its monomerization and interaction with the E3 ubiquitin ligase COP1, leading ultimately to gene expression changes. UVR8 is inactivated through redimerization, facilitated by RUP1 and RUP2. Here, we describe a semidominant, hyperactive allele, namely uvr8-17D, that harbors a glycine-101 to serine mutation. UVR8(G101S) overexpression led to weak constitutive photomorphogenesis and extreme UV-B responsiveness. UVR8(G101S) was observed to be predominantly monomeric in vivo and, once activated by UV-B, was not efficiently inactivated. Analysis of a UVR8 crystal structure containing the G101S mutation revealed the distortion of a loop region normally involved in stabilization of the UVR8 homodimer. Plants expressing a UVR8 variant combining G101S with the previously described W285A mutation exhibited robust constitutive photomorphogenesis. This work provides further insight into UVR8 activation and inactivation mechanisms and describes a genetic tool for the manipulation of photomorphogenic responses.
A constitutively monomeric UVR8 photoreceptor confers enhanced UV-B photomorphogenesis.,Podolec R, Lau K, Wagnon TB, Hothorn M, Ulm R Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). pii: 2017284118. doi:, 10.1073/pnas.2017284118. PMID:33542100[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Kaiserli E, Jenkins GI. UV-B promotes rapid nuclear translocation of the Arabidopsis UV-B specific signaling component UVR8 and activates its function in the nucleus. Plant Cell. 2007 Aug;19(8):2662-73. Epub 2007 Aug 24. PMID:17720867 doi:http://dx.doi.org/10.1105/tpc.107.053330
- ↑ Brown BA, Jenkins GI. UV-B signaling pathways with different fluence-rate response profiles are distinguished in mature Arabidopsis leaf tissue by requirement for UVR8, HY5, and HYH. Plant Physiol. 2008 Feb;146(2):576-88. Epub 2007 Nov 30. PMID:18055587 doi:http://dx.doi.org/10.1104/pp.107.108456
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- ↑ Gruber H, Heijde M, Heller W, Albert A, Seidlitz HK, Ulm R. Negative feedback regulation of UV-B-induced photomorphogenesis and stress acclimation in Arabidopsis. Proc Natl Acad Sci U S A. 2010 Nov 16;107(46):20132-7. doi:, 10.1073/pnas.0914532107. Epub 2010 Nov 1. PMID:21041653 doi:http://dx.doi.org/10.1073/pnas.0914532107
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- ↑ Rizzini L, Favory JJ, Cloix C, Faggionato D, O'Hara A, Kaiserli E, Baumeister R, Schafer E, Nagy F, Jenkins GI, Ulm R. Perception of UV-B by the Arabidopsis UVR8 protein. Science. 2011 Apr 1;332(6025):103-6. doi: 10.1126/science.1200660. PMID:21454788 doi:http://dx.doi.org/10.1126/science.1200660
- ↑ Demkura PV, Ballare CL. UVR8 mediates UV-B-induced Arabidopsis defense responses against Botrytis cinerea by controlling sinapate accumulation. Mol Plant. 2012 May;5(3):642-52. doi: 10.1093/mp/sss025. Epub 2012 Mar 23. PMID:22447155 doi:http://dx.doi.org/10.1093/mp/sss025
- ↑ Davey MP, Susanti NI, Wargent JJ, Findlay JE, Paul Quick W, Paul ND, Jenkins GI. The UV-B photoreceptor UVR8 promotes photosynthetic efficiency in Arabidopsis thaliana exposed to elevated levels of UV-B. Photosynth Res. 2012 Dec;114(2):121-31. doi: 10.1007/s11120-012-9785-y. Epub 2012, Nov 19. PMID:23161229 doi:http://dx.doi.org/10.1007/s11120-012-9785-y
- ↑ O'Hara A, Jenkins GI. In vivo function of tryptophans in the Arabidopsis UV-B photoreceptor UVR8. Plant Cell. 2012 Sep;24(9):3755-66. doi: 10.1105/tpc.112.101451. Epub 2012 Sep, 25. PMID:23012433 doi:http://dx.doi.org/10.1105/tpc.112.101451
- ↑ Cloix C, Kaiserli E, Heilmann M, Baxter KJ, Brown BA, O'Hara A, Smith BO, Christie JM, Jenkins GI. C-terminal region of the UV-B photoreceptor UVR8 initiates signaling through interaction with the COP1 protein. Proc Natl Acad Sci U S A. 2012 Oct 2;109(40):16366-70. doi:, 10.1073/pnas.1210898109. Epub 2012 Sep 17. PMID:22988111 doi:http://dx.doi.org/10.1073/pnas.1210898109
- ↑ Podolec R, Lau K, Wagnon TB, Hothorn M, Ulm R. A constitutively monomeric UVR8 photoreceptor confers enhanced UV-B photomorphogenesis. Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). pii: 2017284118. doi:, 10.1073/pnas.2017284118. PMID:33542100 doi:http://dx.doi.org/10.1073/pnas.2017284118
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