UV-B induction of the E3 ligase ARIADNE12 depends on CONSTITUTIVELY PHOTOMORPHOGENIC 1

Abstract

The UV-B inducible ARIADNE12 (ARI12) gene of Arabidopsis thaliana is a member of the RING-between-RING (RBR) family of E3 ubiquitin ligases for which a novel ubiquitination mechanism was identified in mammalian homologs. This RING-HECT hybrid mechanism needs a conserved cysteine which is replaced by serine in ARI12 and might affect the E3 ubiquitin ligase activity. We have shown that under photomorphogenic UV-B, ARI12 is a downstream target of the classical ultraviolet B (UV-B) UV RESISTANCE LOCUS 8 (UVR8) pathway. However, under high fluence rate of UV-B ARI12 was induced independently of UVR8 and the UV-A/blue light and red/far-red photoreceptors. A key component of several light signaling pathways is CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). Upon UV-B COP1 is trapped in the nucleus through interaction with UVR8 permitting the activation of genes that regulate the biosynthesis of UV-B protective metabolites and growth adaptations. To clarify the role of COP1 in the regulation of ARI12 mRNA expression and ARI12 protein stability, localization and interaction with COP1 was assessed with and without UV-B. We found that COP1 controls ARI12 in white light, low and high fluence rate of UV-B. Furthermore we show that ARI12 is indeed an E3 ubiquitin ligase which is mono-ubiquitinated, a prerequisite for the RING-HECT hybrid mechanism. Finally, genetic analyses with transgenes expressing a genomic pmARI12:ARI12-GFP construct confirm the epistatic interaction between COP1 and ARI12 in growth responses to high fluence rate UV-B.

PUB11-Dependent Ubiquitination of the Phospholipid Flippase ALA10 Modifies ALA10 Localization and Affects the Pool of Linolenic Phosphatidylcholine

“…What is then the function of the PUB11-dependent ubiquitination of ALA10? Several possible functions of ubiquitin modification have already been reported in plants, from alteration of abundance to modification of localization and shift in interaction properties (Guerra and Callis, 2012;Xie et al, 2015). Here we show that PUB11 does not seem to have an impact on ALA10 abundance but rather influences ALA10 localization.…”

Photomorphogenic responses to ultraviolet‐B light

“…1, Kliebenstein et al (); 2, Brown et al (); 3, Brown & Jenkins (); 4, Favory et al (); 5, Brown et al (); 6, Gruber et al (); 7, Feher et al (); 8, Davey et al (); 9, Lang‐Mladek et al (); 10, Morales et al (); 11, Wargent et al (); 12, Demkura & Ballaré (); 13, Cloix et al (); 14, Huang et al (); 15, Heijde et al (); 16, Fasano et al (); 17, Tossi et al (); 18, Huang et al (); 19, Vandenbussche et al (); 20, Hayes et al (); 21, Binkert et al (); 22, Fierro et al (); 23, Mazza & Ballaré ; 24, Xie et al (); 25, Li et al (); 26, Yin et al (); 27, Tilbrook et al (); 28, Velanis et al (); 29, Heilmann et al (). 30, Hayes et al ().…”

“…In addition, other processes may be regulated by a combination of UV‐B pathways. Various genes, including those encoding the cyclobutane pyrimidine dimer photolyase PHR1 (Li et al ) and the E3 ubiquitin ligase ARIADNE12 (Xie et al ) are regulated by both UVR8 and non‐UVR8 pathways, depending on the spectral quality and fluence rate.…”

Involvement of the eIF2α Kinase GCN2 in UV-B Responses

“…Explanations are still elusive why different action spectra are necessary for UVR8 monomerization and UV-B induced HY5 expression and whether UVR8 is the only UV-B photoreceptor or if additional factors are needed to modulate the action of UVR8 (Brown et al, 2009; Díaz-Ramos et al, 2018). UV-B responsive phenomena in mutants of uvr8 and photobiological studies indicate that UV-B signaling might also be triggered by other pathways (Ulm et al, 2004; Safrany et al, 2008; Gardner et al, 2009; Shinkle et al, 2010; Leasure et al, 2011; Lang-Mladek et al, 2012; Tilbrook et al, 2013; Xie et al, 2015; O’Hara et al, 2019). Studies also suggested that reduced pterin may be a chromophore for a putative UV-B photoreceptor (Galland and Senger, 1988; Takeda et al, 2014).…”