6qec
DNA binding domain of LUX ARRYTHMO in complex with DNA
Structural highlights
FunctionPCL1_ARATH Transcription factor that is essential for the generation of the circadian clock oscillation. Is necessary for activation of CCA1 and LHY expression. Is coregulated with TOC1 and seems to be repressed by CCA1 and LHY by direct binding of these proteins to the evening element in the LUX promoter. Directly regulates the expression of PRR9, a major component of the morning transcriptional feedback circuit, by binding specific sites on PRR9 promoter. Binds to its own promoter, inducing a negative auto-regulatory feedback loop within the core clock. Binds to ELF3 and associates with ELF4 in a diurnal complex which is required for the expression of the growth-promoting transcription factors PIF4 and PIF5 and subsequent hypocotyl growth in the early evening.[1] [2] [3] [4] [5] Publication Abstract from PubMedThe Evening Complex (EC), composed of the DNA binding protein LUX ARRHYTHMO (LUX) and two additional proteins EARLY FLOWERING 3 (ELF3) and ELF4, is a transcriptional repressor complex and a core component of the plant circadian clock. In addition to maintaining oscillations in clock gene expression, the EC also participates in temperature and light entrainment, acting as an important environmental sensor and conveying this information to growth and developmental pathways. However, the molecular basis for EC DNA binding specificity and temperature-dependent activity were not known. Here, we solved the structure of the DNA binding domain of LUX in complex with DNA. Residues critical for high-affinity binding and direct base readout were determined and tested via site-directed mutagenesis in vitro and in vivo. Using extensive in vitro DNA binding assays of LUX alone and in complex with ELF3 and ELF4, we demonstrate that, while LUX alone binds DNA with high affinity, the LUX-ELF3 complex is a relatively poor binder of DNA. ELF4 restores binding to the complex. In vitro, the full EC is able to act as a direct thermosensor, with stronger DNA binding at 4 degrees C and weaker binding at 27 degrees C. In addition, an excess of ELF4 is able to restore EC binding even at 27 degrees C. Taken together, these data suggest that ELF4 is a key modulator of thermosensitive EC activity. Molecular mechanisms of Evening Complex activity in Arabidopsis.,Silva CS, Nayak A, Lai X, Hutin S, Hugouvieux V, Jung JH, Lopez-Vidriero I, Franco-Zorrilla JM, Panigrahi KCS, Nanao MH, Wigge PA, Zubieta C Proc Natl Acad Sci U S A. 2020 Mar 24;117(12):6901-6909. doi:, 10.1073/pnas.1920972117. Epub 2020 Mar 12. PMID:32165537[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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