FHY1 and FHL Act Together to Mediate Nuclear Accumulation of the Phytochrome A Photoreceptor

Hiltbrunner, Andreas; Tscheuschler, Anke; Viczián, András; Kunkel, Tim; Kircher, Stefan; Schäfer, Eberhard

doi:10.1093/pcp/pcj087

Cited by 161 publications

(220 citation statements)

References 54 publications

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“…For example, FAR-RED ELONGATED HYPOCOTYL1 (FHY1) and its homolog FHY1-LIKE (FHL) have been shown to form homodimers and heterodimers and then act together to regulate downstream events in Phytochrome A (PHYA) signaling, such as nuclear accumulation of PHYA and inhibition of hypocotyl elongation (Zhou et al, 2005;Hiltbrunner et al, 2006;Yang et al, 2009). Similarly, SPAs (for SUPPRESSOR OF PHYA) 1, 2, 3, and 4 are highly homologous proteins that can form homo-or heterodimers.…”

Section: Discussionmentioning

confidence: 99%

DWA1 and DWA2, Two Arabidopsis DWD Protein Components of CUL4-Based E3 Ligases, Act Together as Negative Regulators in ABA Signal Transduction

et al. 2010

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To elucidate potential roles of CUL4-DDB1-DWD (for Cullin 4-Damaged DNA Binding1-DDB1 binding WD40) E3 ligases in abscisic acid (ABA) signaling, we examined ABA sensitivities of T-DNA mutants of a number of Arabidopsis thaliana DWD genes, which encode substrate receptors for CUL4 E3 ligases. Mutants in two DWD genes, DWA1 and DWA2 (DWD hypersensitive to ABA1 and 2), had ABA-hypersensitive phenotypes. Both proteins interacted with DDB1 in yeast two-hybrid assays and associated with DDB1 and CUL4 in vivo, implying they could form CUL4-based complexes. Several ABAresponsive genes were hyperinduced in both mutants, and the ABA-responsive transcription factors ABA INSENSITIVE 5 (ABI5) and MYC2 accumulated to high levels in the mutants after ABA treatment. Moreover, ABI5 interacted with DWA1 and DWA2 in vivo. Cell-free degradation assays showed ABI5 was degraded more slowly in dwa1 and dwa2 than in wild-type cell extracts. Therefore, DWA1 and/or DWA2 may be the substrate receptors for a CUL4 E3 ligase that targets ABI5 for degradation. Our data indicate that DWA1 and DWA2 can directly interact with each other, and their double mutants exhibited enhanced ABA and NaCl hypersensitivities, implying they can act together. This report thus describes a previously unknown heterodimeric cooperation between two independent substrate receptors for CUL4-based E3 ligases.

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Section: Discussionmentioning

confidence: 99%

DWA1 and DWA2, Two Arabidopsis DWD Protein Components of CUL4-Based E3 Ligases, Act Together as Negative Regulators in ABA Signal Transduction

et al. 2010

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“…In addition to these VLFR-specific components, several other signaling intermediates have been demonstrated to be important for both FR-HIR and VLFR. These include FHY1 and FHY1-LIKE, two proteins necessary for the import of phyA into the nucleus upon light activation (see Supplemental Figure 1 online; Zeidler et al, 2004;Hiltbrunner et al, 2005Hiltbrunner et al, , 2006Zhou et al, 2005;Rosler et al, 2007;Genoud et al, 2008) and some members of the PKS1 and SPA1 protein family. The cytoplasmic PKS1 and 2 proteins, which can interact with phyA, show enhanced phyA-mediated VLFR and are also involved in blue light-dependent phototropism (Fankhauser et al, 1999;Lariguet et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

OWL1: An Arabidopsis J-Domain Protein Involved in Perception of Very Low Light Fluences

Kneissl¹,

Wachtler

Chua

et al. 2009

Plant Cell

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“…Both proteins interact in a light-dependent manner with phyA and bear a functional nuclear localization signal (NLS) and nuclear exclusion signal (13,14,(17)(18)(19)(20). In the absence of FHY1 and FHL phyA remains in the cytoplasm and nuclear accumulation of phyA is no longer detected after light irradiation (13).…”

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confidence: 99%

Interaction with plant transcription factors can mediate nuclear import of phytochrome B

Pfeiffer¹,

Nagel²,

Popp³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Phytochromes (phy) are red/far-red-absorbing photoreceptors that regulate the adaption of plant growth and development to changes in ambient light conditions. The nuclear transport of the phytochromes upon light activation is regarded as a key step in phytochrome signaling. Although nuclear import of phyA is regulated by the transport facilitators far red elongated hypocotyl 1 (FHY1) and fhy1-like, an intrinsic nuclear localization signal was proposed to be involved in the nuclear accumulation of phyB. We recently showed that nuclear import of phytochromes can be analyzed in a cell-free system consisting of isolated nuclei of the unicellular green algae Acetabularia acetabulum. We now show that this system is also versatile to elucidate the mechanism of the nuclear transport of phyB. We tested the nuclear transport characteristics of full-length phyB as well as N-and C-terminal phyB fragments in vitro and showed that the nuclear import of phyB can be facilitated by phytochrome-interacting factor 3 (PIF3). In vivo measurements of phyB nuclear accumulation in the absence of PIF1, -3, -4, and -5 indicate that these PIFs are the major transport facilitators during the first hours of deetiolation. Under prolonged irradiations additional factors might be responsible for phyB nuclear transport in the plant.Arabidopsis | basic helix-loop-helix | signal transduction P lant development is strictly regulated by the environmental light conditions. Even though light is ubiquitously present, spectral composition, intensity, and light direction varies depending on the local environment. To adapt on local light conditions plants are equipped with a highly developed repertory of photoreceptors (1, 2).Plant phytochromes are mainly involved in detection of red and far-red light wavelengths of the spectrum. A family of five members in Arabidopsis thaliana regulates the major developmental steps in the life of the plant: germination, photomorphogenesis, and flowering (3, 4). Despite the sequence similarities and identical spectroscopic features, the two major phytochromes, phyA and phyB, show overlapping as well as unique photosensory and functional characteristics (5-7). The light-stable phyB mediates red/far-red reversible low fluence response, whereas the light-labile phyA, is involved in far-red light sensing (high irradiance response) and in responses to very weak light (very low fluence response, VLFR) (8).Phytochromes are cytosolic proteins of 125 kDa that are translocated into the nucleus upon light activation (6, 9-11). Nuclear transport is an essential step in phytochrome signaling and a prerequisite for the interaction with transcription factors in the nucleus (12, 13). Concerning the kinetics of nuclear import, severe differences can be found between the two major plant phytochromes, phyA and phyB (6). PhyA cannot be detected in nuclei of dark-grown plants but is rapidly transported into the nucleus upon light irradiation. In contrast, low levels of phyB are present in the nucleus even in dark-grown seedlings. The nuclea...

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FHY1 and FHL Act Together to Mediate Nuclear Accumulation of the Phytochrome A Photoreceptor

Cited by 161 publications

References 54 publications

DWA1 and DWA2, Two Arabidopsis DWD Protein Components of CUL4-Based E3 Ligases, Act Together as Negative Regulators in ABA Signal Transduction

DWA1 and DWA2, Two Arabidopsis DWD Protein Components of CUL4-Based E3 Ligases, Act Together as Negative Regulators in ABA Signal Transduction

OWL1: An Arabidopsis J-Domain Protein Involved in Perception of Very Low Light Fluences

Interaction with plant transcription factors can mediate nuclear import of phytochrome B

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