Arabidopsis CULLIN4-Damaged DNA Binding Protein 1 Interacts with CONSTITUTIVELY PHOTOMORPHOGENIC1-SUPPRESSOR OF PHYA Complexes to Regulate Photomorphogenesis and Flowering Time  

Abstract

CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) possesses E3 ligase activity and promotes degradation of key factors involved in the light regulation of plant development. The finding that CULLIN4 (CUL4)-Damaged DNA Binding Protein1 (DDB1) interacts with DDB1 binding WD40 (DWD) proteins to act as E3 ligases implied that CUL4-DDB1 may associate with COP1-SUPPRESSOR OF PHYA (SPA) protein complexes, since COP1 and SPAs are DWD proteins. Here, we demonstrate that CUL4-DDB1 physically associates with COP1-SPA complexes in vitro and in vivo, likely via direct interaction of DDB1 with COP1 and SPAs. The interactions between DDB1 and COP1, SPA1, and SPA3 were disrupted by mutations in the WDXR motifs of MBP-COP1, His-SPA1, and His-SPA3. CUL4 cosuppression mutants enhanced weak cop1 photomorphogenesis and flowered early under short days. Early flowering of short day-grown cul4 mutants correlated with increased FLOWERING LOCUS T transcript levels, whereas CONSTANS transcript levels were not altered. De-etiolated1 and COP1 can bind DDB1 and may work with CUL4-DDB1 in distinct complexes, but they mediate photomorphogenesis in concert. Thus, a series of CUL4-DDB1-COP1-SPA E3 ligase complexes may mediate the repression of photomorphogenesis and, possibly, of flowering time.

CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1

“…The plates were kept at 4°C in the dark for 3 to 4 days to stratify and then exposed to 3 h of white light at room temperature before being placed in the dark for 21 h. The plates were incubated at 21°C for an additional 3 days in the dark or light as indicated. Arabidopsis thaliana wild type and various mutants (pif1, cop1-4, cop1-6, spa1, spa2, spa12, spa123, spa124, spaQ, cul1-6, cul3a, cul3b, cul3ab, cul4-1 and cul4cs) in the Col-0 background were used 6,32,[40][41][42][43][44][45][46][47][48] . For generation of different spaQpif1 mutant, pif1 and spaQ were crossed to obtain the F1 seeds.…”

“…The TAP-PIF1, TAP-SPA1, Flag-CUL4, TAP-SPA1/PIF1-HA and TAP-PIF1/COP1-HA transgenic plants have been previously described 6,7,20,29 . The PIF1-HA-pGWB14 plasmid was described 7 .…”

“…COP1 forms multiple complexes with SUPPRESSOR OF PHYA-105 (SPA1-4) family members 5 . These complexes, either by themselves or by forming CUL4 COP1-SPA E3 ubiquitin ligases, degrade the positively acting transcription factors through the ubiquitin proteasome system (UPS) to repress photomorphogenesis in the dark 6 . Strikingly, PIF1 directly interacts with COP1 and SPA complex and acts as a cofactor of COP1 E3 ubiquitin ligase to synergistically degrade the positively acting factor HY5 to repress photomorphogenesis in the dark 7 .…”

MLN4924 Is an Efficient Inhibitor of NEDD8 Conjugation in Plants

“…Besides SCF TIR1/AFB1-3 , CUL1-type E3s have been implicated in the degradation of DELLA regulators in response to the phytohormone GA [SCF SLEEPY(SLY1) ; Dill et al, 2004] and the cell cycle inhibitor KIP1-RELATED PROTEIN1 (KRP1; [SCF SKP2b ]; Ren et al, 2008). The best-characterized CUL4 CRL from Arabidopsis acts together with DDB1, CONSTITUTIVELY PHOTOMORPHOGENIC1, DEETIOLATED1, and SUPRESSOR-OF-phyA-1051 to promote the degradation of the transcription factor ELONGATED HYPOCOT-YL5 (HY5) that normally represses hypocotyl elongation in light-grown Arabidopsis seedlings (Osterlund et al, 2000;Yanagawa et al, 2004;Chen et al, 2006Chen et al, , 2010.…”

A reverse genetics approach identifies novel mutants in light responses and anthocyanin metabolism in petunia

“…By reverse genetics, we have identified candidate genes to regulators of shade-avoidance responses; ATHB2 orthologs (Ciarbelli et al 2008), photomorphogenesis and seedling establishment; FHY3/FAR1, NDPK2, PIF/PIL family, PP7, RAP1/ ATMYC2, RFI2 (Shen et al 2005;Yadav et al 2005;Chen and Ni 2006;Lin et al 2007;Genoud et al 2008;Leivar et al 2008), light-regulated proteolysis; COP1, EID1, LAF1, SPA1 (Yi and Deng 2005;Marrocco et al 2006;Yang et al 2009;Chen et al 2010;Fankhauser and Ulm 2011) and developmental transitions; CO, PFT1 (Suárez-López et al 2001;Cerdán and Chory 2003) (Table S2). Using the obtained sequence information in a reverse genetics approach, we have identified a novel petunia mutant carrying a mutation in CCT (CO, CO-like, TOC1) domain (Strayer et al 2000;Valverde 2011).…”