Arabidopsis COP1 acts as a repressor of photomorphogenesis in darkness, and light stimuli abrogate the repressive ability and nuclear abundance of COP1. COP1 has three known structural modules: an N-terminal RING-finger, followed by a predicted coiled-coil and C-terminal WD-40 repeats. A systematic study was undertaken to dissect the functional roles of these three COP1 domains in light control...

The Artemisia annua L. β-pinene synthase QH6 was previously determined to be circadian-regulated at the transcriptional level, showing a rhythmic fluctuation of steady-state transcript abundances. Here we isolated both the genomic sequence and upstream promoter region of QH6. Different regulatory elements, such as G-box (TGACACGTGGCA, -421 bp from the translation initiation site) which might ha...

The reaction center core of photosystem II is composed of two chlorophyll binding proteins, D1 and D2, that are encoded by the chloroplast genes psbA and psbD. These chlorophyll binding proteins are damaged during photochemistry, especially under high irradiance. Photosystem II function is maintained under these conditions through turnover and resynthesis of D1 and D2. Blue light-activated tran...

In higher plants, light is crucial for regulation of nitrate uptake, translocation and assimilation into organic compounds. Part of this metabolism is tightly coupled to photosynthesis because the enzymes involved, nitrite reductase and glutamate synthase, are localized to the chloroplasts and receive reducing power from photosynthetic electron transport. However, important enzymes in nitrate a...

The COP9 signalosome (CSN) is an evolutionarily conserved multiprotein complex that mediates the repression of photomorphogenesis in the dark in Arabidopsis through the degradation of transcription factors such as HY5 and HYH. CSN-mediated HY5 and HYH degradation also requires the activity of the putative E3 ubiquitin ligase (E3) component COP1 and the E2-conjugating enzyme variant COP10. Recen...

Plants respond to low levels of UV-B radiation with a coordinated photomorphogenic response that allows acclimation to this environmental stress factor. The key players in this UV-B response are COP1 (an E3 ubiquitin ligase), UVR8 (a β-propeller protein), and HY5 (a bZIP transcription factor). We have shown previously that an elevated UV-B-specific response is associated with dwarf growth, indi...

Arabidopsis thaliana UV RESISTANCE LOCUS8 (UVR8) is a UV-B-specific signaling component that binds to chromatin and regulates UV protection by orchestrating expression of a range of genes. Here, we studied how UV-B regulates UVR8. We show that UV-B stimulates the nuclear accumulation of both a green fluorescent protein (GFP)-UVR8 fusion and native UVR8. Nuclear accumulation leads to UV-B induct...

Light regulates plant growth and development via multiple photoreceptors including phytochromes and cryptochromes. Although the functions of photoreceptors have been studied extensively, questions remain regarding the involvement of cryptochromes in photomorphogenesis. In this study, we identified a protein, TEOSINTE-LIKE1, CYCLOIDEA, and PROLIFERATING CELL FACTOR 2 (TCP2), which interacts with...