The homeodomain-leucine zipper ATHB23, a phytochrome B-interacting protein, is important for phytochrome B-mediated red light signaling

2013 ◽  
Vol 150 (2) ◽  
pp. 308-320 ◽  
Author(s):  
Hyunmo Choi ◽  
Suyeong Jeong ◽  
Dong Su Kim ◽  
Hyung Jin Na ◽  
Jong Sang Ryu ◽  
...  
Keyword(s):  
Leucine Zipper ◽  
Red Light ◽  
Light Signaling ◽  
Phytochrome B ◽  
Interacting Protein

scholarly journals SUMOylation of phytochrome-B negatively regulates light-induced signaling in Arabidopsis thaliana

2015 ◽  
Vol 112 (35) ◽  
pp. 11108-11113 ◽  
Author(s):  
Ari Sadanandom ◽  
Éva Ádám ◽  
Beatriz Orosa ◽  
András Viczián ◽  
Cornelia Klose ◽  
...  
Keyword(s):  
Molecular Level ◽  
Expression Patterns ◽  
Red Light ◽  
Regulatory Proteins ◽  
Light Signaling ◽  
Phytochrome B ◽  
Sumo Proteases ◽  
C Terminus

The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, λmax, 660 nm) and active (Pfr; λmax, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with a battery of downstream regulatory proteins, including PHYTOCHROME INTERACTING FACTOR transcription factors, and by modulating their activity/abundance, it alters expression patterns of genes underlying photomorphogenesis. Here we report that the small ubiquitin-like modifier (SUMO) is conjugated (SUMOylation) to the C terminus of phyB; the accumulation of SUMOylated phyB is enhanced by red light and displays a diurnal pattern in plants grown under light/dark cycles. Our data demonstrate that (i) transgenic plants expressing the mutant phyBLys996Arg-YFP photoreceptor are hypersensitive to red light, (ii) light-induced SUMOylation of the mutant phyB is drastically decreased compared with phyB-YFP, and (iii) SUMOylation of phyB inhibits binding of PHYTOCHROME INTERACTING FACTOR 5 to phyB Pfr. In addition, we show that OVERLY TOLERANT TO SALT 1 (OTS1) de-SUMOylates phyB in vitro, it interacts with phyB in vivo, and the ots1/ots2 mutant is hyposensitive to red light. Taken together, we conclude that SUMOylation of phyB negatively regulates light signaling and it is mediated, at least partly, by the action of OTS SUMO proteases.

scholarly journals PCH1 integrates circadian and light-signaling pathways to control photoperiod-responsive growth in Arabidopsis

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
He Huang ◽  
Chan Yul Yoo ◽  
Rebecca Bindbeutel ◽  
Jessica Goldsworthy ◽  
Allison Tielking ◽  
...  
Keyword(s):  
Light Exposure ◽  
Red Light ◽  
Constitutive Expression ◽  
Day Length ◽  
Light Signaling ◽  
Dependent Manner ◽  
Phytochrome B ◽  
Necessary And Sufficient ◽  
New Protein ◽  
Short Days

Plants react to seasonal change in day length through altering physiology and development. Factors that function to harmonize growth with photoperiod are poorly understood. Here we characterize a new protein that associates with both circadian clock and photoreceptor components, named PHOTOPERIODIC CONTROL OF HYPOCOTYL1 (PCH1). pch1 seedlings have overly elongated hypocotyls specifically under short days while constitutive expression of PCH1 shortens hypocotyls independent of day length. PCH1 peaks at dusk, binds phytochrome B (phyB) in a red light-dependent manner, and co-localizes with phyB into photobodies. PCH1 is necessary and sufficient to promote the biogenesis of large photobodies to maintain an active phyB pool after light exposure, potentiating red-light signaling and prolonging memory of prior illumination. Manipulating PCH1 alters PHYTOCHROME INTERACTING FACTOR 4 levels and regulates light-responsive gene expression. Thus, PCH1 is a new factor that regulates photoperiod-responsive growth by integrating the clock with light perception pathways through modulating daily phyB-signaling.

scholarly journals PCH1 regulates light, temperature, and circadian signaling as a structural component of phytochrome B-photobodies in Arabidopsis

2019 ◽  
Author(s):  
He Huang ◽  
Katrice E. McLoughlin ◽  
Maria L. Sorkin ◽  
E. Sethe Burgie ◽  
Rebecca K. Bindbeutel ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Structural Component ◽  
Genetic Interaction ◽  
Red Light ◽  
Early Event ◽  
Plant Responses ◽  
Phytochrome B ◽  
Thermal Perception ◽  
Interacting Protein

AbstractThe phytochrome (phy) family of bilin-containing photoreceptors are major regulators of plant photomorphogenesis through their unique ability to photointerconvert between a biologically inactive red light-absorbing Pr state and an active far-red light­absorbing Pfr state. While the initial steps in Pfr signaling are unclear, an early event for the phyB isoform after photoconversion is its redistribution from the cytoplasm into subnuclear foci named photobodies (PBs) that dissipate after Pfr reverts back to Pr by far-red irradiation or by temperature-dependent non-photochemical reversion. Here we present evidence that PHOTOPERIODIC CONTROL OF HYPOCOTYL 1 (PCH1) functions both as an essential structural component of phyB-containing PBs and as a direct regulator of thermal reversion that is sufficient to stabilize phyB as Pfr in vitro. By examining the genetic interaction between a constitutively active phyBY276H-YFP allele (YHB-YFP) and PCH1, we show that the loss of PCH1 prevents YHB from coalescing into PBs without affecting its nuclear localization, whereas overexpression of PCH1 dramatically increases PB levels. Loss of PCH1, presumably by impacting phyB-PB assembly, compromises a number of events elicited in YHB-YFP plants, including their constitutive photomorphogenic phenotype, red light-regulated thermomorphogenesis, and input of phyB into the circadian clock. Conversely, elevated levels of both phyB and PCH1 generate stable, yet far red-light reversible PBs that persisted for days. Collectively, our data demonstrate that the assembly of PCHl-containing PBs is critical for phyB signaling to multiple outputs, and suggest that altering PB dynamics could be exploited to modulate plant responses to light and temperature.SignificanceIn Arabidopsis, phytochrome B (phyB) perceives light and temperature signals to regulate various fundamental morphogenic processes in plants through its interconversion between its active Pfr and inactive Pr states. Upon photoconversion from Pr to Pfr, phyB forms subnuclear foci called photobodies, whose composition and molecular function(s) are unclear. We show here that the phyB-interacting protein PCH1 is a structural component of phyB-photobodies and protects Pfr from thermal reversion back to Pr thus helping maintain phyB signaling. Loss of PCH1 compromises photobody formation, which disrupts a number of downstream events including photo- and thermal perception and signaling into the circadian clock. These results demonstrate that forming PCHl-dependent phyB-photobodies is an essential step connecting light and temperature to controls on plant morphogenesis.

scholarly journals BBX4, a phyB-interacting and modulated regulator, directly interacts with PIF3 to fine tune red light-mediated photomorphogenesis

2019 ◽  
Vol 116 (51) ◽  
pp. 26049-26056 ◽  
Author(s):  
Yueqin Heng ◽  
Yan Jiang ◽  
Xianhai Zhao ◽  
Hua Zhou ◽  
Xuncheng Wang ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Red Light ◽  
Plant Cells ◽  
26S Proteasome ◽  
Light Signaling ◽  
Physical Interaction ◽  
Phytochrome B ◽  
Molecular Events ◽  
Light Signals ◽  
Fine Tune

Phytochrome B (phyB) absorbs red light signals and subsequently initiates a set of molecular events in plant cells to promote photomorphogenesis. Here we show that phyB directly interacts with B-BOX CONTAINING PROTEIN 4 (BBX4), a positive regulator of red light signaling, and positively controls its abundance in red light. BBX4 associates with PHYTOCHROME INTERACTING FACTOR 3 (PIF3) and represses PIF3 transcriptional activation activity and PIF3-controlled gene expression. The degradation of BBX4 in darkness is dependent on CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) and the 26S proteasome system. Collectively, BBX4 acts as a key component of the phyB-PIF3–mediated signaling module and fine tunes the red light action. phyB promotes the accumulation of BBX4, which in turn serves to repress PIF3 action through direct physical interaction to promote photomorphogenic development in red light.

scholarly journals Glucocorticoid Receptor Phosphorylation Differentially Affects Target Gene Expression

2008 ◽  
Vol 22 (8) ◽  
pp. 1754-1766 ◽  
Author(s):  
Weiwei Chen ◽  
Thoa Dang ◽  
Raymond D. Blind ◽  
Zhen Wang ◽  
Claudio N. Cavasotto ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Transcriptional Activation ◽  
Leucine Zipper ◽  
Target Genes ◽  
Divalent Cations ◽  
Phosphorylation Site ◽  
Transcriptional Response ◽  
Receptor Occupancy ◽  
Wild Type ◽  
Interacting Protein

Abstract The glucocorticoid receptor (GR) is phosphorylated at multiple sites within its N terminus (S203, S211, S226), yet the role of phosphorylation in receptor function is not understood. Using a range of agonists and GR phosphorylation site-specific antibodies, we demonstrated that GR transcriptional activation is greatest when the relative phosphorylation of S211 exceeds that of S226. Consistent with this finding, a replacement of S226 with an alanine enhances GR transcriptional response. Using a battery of compounds that perturb different signaling pathways, we found that BAPTA-AM, a chelator of intracellular divalent cations, and curcumin, a natural product with antiinflammatory properties, reduced hormone-dependent phosphorylation at S211. This change in GR phosphorylation was associated with its decreased nuclear retention and transcriptional activation. Molecular modeling suggests that GR S211 phosphorylation promotes a conformational change, which exposes a novel surface potentially facilitating cofactor interaction. Indeed, S211 phosphorylation enhances GR interaction with MED14 (vitamin D receptor interacting protein 150). Interestingly, in U2OS cells expressing a nonphosphorylated GR mutant S211A, the expression of IGF-binding protein 1 and interferon regulatory factor 8, both MED14-dependent GR target genes, was reduced relative to cells expressing wild-type receptor across a broad range of hormone concentrations. In contrast, the induction of glucocorticoid-induced leucine zipper, a MED14-independent GR target, was similar in S211A- and wild-type GR-expressing cells at high hormone levels, but was reduced in S211A cells at low hormone concentrations, suggesting a link between GR phosphorylation, MED14 involvement, and receptor occupancy. Phosphorylation also affected the magnitude of repression by GR in a gene-selective manner. Thus, GR phosphorylation at S211 and S226 determines GR transcriptional response by modifying cofactor interaction. Furthermore, the effect of GR S211 phosphorylation is gene specific and, in some cases, dependent upon the amount of activated receptor.

scholarly journals Arabidopsis Phytochrome B Promotes SPA1 Nuclear Accumulation to Repress Photomorphogenesis under Far-Red Light

2013 ◽  
Vol 25 (1) ◽  
pp. 115-133 ◽  
Author(s):  
Xu Zheng ◽  
Suowei Wu ◽  
Huqu Zhai ◽  
Peng Zhou ◽  
Meifang Song ◽  
...  
Keyword(s):  
Red Light ◽  
Nuclear Accumulation ◽  
Phytochrome B

scholarly journals MondoA-Mlx Transcriptional Activity Is Limited by mTOR-MondoA Interaction

2014 ◽  
Vol 35 (1) ◽  
pp. 101-110 ◽  
Author(s):  
Mohan R. Kaadige ◽  
Jingye Yang ◽  
Blake R. Wilde ◽  
Donald E. Ayer
Keyword(s):  
Glucose Uptake ◽  
Leucine Zipper ◽  
Aerobic Glycolysis ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Nutrient Status ◽  
Regulatory Relationship ◽  
Interacting Protein ◽  
Thioredoxin Interacting Protein ◽  
Helix Loop Helix

Mammalian target of rapamycin (mTOR) integrates multiple signals, including nutrient status, growth factor availability, and stress, to regulate cellular and organismal growth. How mTOR regulates transcriptional programs in response to these diverse stimuli is poorly understood. MondoA and its obligate transcription partner Mlx are basic helix-loop-helix leucine zipper (bHLHZip) transcription factors that sense and execute a glucose-responsive transcriptional program. MondoA-Mlx complexes activate expression of thioredoxin-interacting protein (TXNIP), which is a potent inhibitor of cellular glucose uptake and aerobic glycolysis. Both mTOR and MondoA are central regulators of glucose metabolism, yet whether they interact physically or functionally is unknown. We show that inhibition of mTOR induces MondoA-dependent expression of TXNIP, coinciding with reduced glucose uptake. Mechanistically, mTOR binds to MondoA in the cytoplasm and prevents MondoA-Mlx complex formation, restricting MondoA's nuclear entry and reducing TXNIP expression. Further, we show that mTOR inhibitors and reactive oxygen species (ROS) regulate interaction between MondoA and mTOR in an opposing manner. Like mTOR's suppression of the MondoA-TXNIP axis, MondoA can also suppress mTOR complex 1 (mTORC1) activity via its direct transcriptional regulation of TXNIP. Collectively, these studies reveal a regulatory relationship between mTOR and the MondoA-TXNIP axis that we propose contributes to glucose homeostasis.

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