Serine-to-alanine substitutions at the amino-terminal region of phytochrome A result in an increase in biological activity.

Stockhaus, Jörg; Nagatani, Akira; Halfter, Ursula; Kay, S. A.; Furuya, Masaki; Chua, Nam‐Hai

doi:10.1101/gad.6.12a.2364

Cited by 109 publications

(95 citation statements)

References 20 publications

(31 reference statements)

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“…Several observations and indirect lines of evidence for the possible role of protein phosphorylation downstream of the phytochrome-mediated light signal transduction pathway have been discussed (Singh and Song, 1990;Elich and Chory, 1997a;Watson, 2000;Sharma, 2001). For example, mutation of N-terminal Ser to Ala results in an increased biological activity of phytochrome A (phyA), suggesting that phytochrome responses might be desensitized by this photoreceptor phosphorylation (Stockhaus et al, 1992;Jordan et al, 1997). However, the in vivo functional role of phytochrome phosphorylation is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Phytochrome Phosphorylation Modulates Light Signaling by Influencing the Protein–Protein Interaction[W]

et al. 2004

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Plant photoreceptor phytochromes are phosphoproteins, but the question as to the functional role of phytochrome phosphorylation has remained to be elucidated. We investigated the functional role of phytochrome phosphorylation in plant light signaling using a Pfr-specific phosphorylation site mutant, Ser598Ala of oat (Avena sativa) phytochrome A (phyA). The transgenic Arabidopsis thaliana (phyA-201 background) plants with this mutant phyA showed hypersensitivity to light, suggesting that phytochrome phosphorylation at Serine-598 (Ser598) in the hinge region is involved in an inhibitory mechanism. The phosphorylation at Ser598 prevented its interaction with putative signal transducers, Nucleoside Diphosphate Kinase-2 and Phytochrome-Interacting Factor-3. These results suggest that phosphorylation in the hinge region of phytochromes serves as a signal-modulating site through the protein–protein interaction between phytochrome and its putative signal transducer proteins.

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Section: Introductionmentioning

confidence: 99%

Phytochrome Phosphorylation Modulates Light Signaling by Influencing the Protein–Protein Interaction[W]

et al. 2004

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“…In attempts to identify functionally important structural domains of oat phyA, severa1 researchers have analyzed the effect of in vitro-generated deletion and amino acid substitution rnutants on the ability of the photoreceptor to cause increased inhibition of hypocotyl or stem elongation when overexpressed in transgenic Arabidopsis or tobacco, respectively (Cherryet al, 1992(Cherryet al, , 1993Stockhaus et al, 1992;Boylan et al, 1994). Taken together, these data indicate that the N-terminal domain is sufficient for spectral integrity but not for normal biological activity of the protein and that regions at the N and C terrnini of phyA are necessary for normal biological activity.…”

Section: Introductionmentioning

confidence: 99%

Two Small Spatially Distinct Regions of Phytochrome B Are Required for Efficient Signaling Rates.

1996

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We used a series of in vitro-generated deletion and amino acid substitution derivatives of phytochrome B (phyB) expressed in transgenic Arabidopsis to identify regions of the molecule important for biological activity. Expression of the chromophore-bearing N-terminal domain of phyB alone resulted in a fully photoactive, monomeric molecule lacking normal regulatory activity. Expression of the C-terminal domain alone resulted in a photoinactive, dimeric molecule, also lacking normal activity. Thus, both domains are necessary, but neither is sufficient for phyB activity. Deletion of a small region on each major domain (residues 6 to 57 and 652 to 712, respectively) was shown to compromise phyB activity differentially without interfering with spectral activity or dimerization. Deletion of residues 6 to 57 caused a large increase in the fluence rate of continuous red light (Rc) required for maximal seedling responsiveness, indicating a marked decrease in efficiency of light signal perception or processing per mole of mutant phyB. In contrast,deletion of residues 652 to 712 resulted in a photoreceptor that retained saturation of seediing responsiveness to Rc at low fluence rates but at a response leve1 much below the maximal response elicited by the parent molecule. This deletion apparently reduces the maximal biological activity per mole of phyB without a major decrease in efficiency of signal perception, thus suggesting disruption of a process downstream of signal perception. In addition, certain phyB constructs caused dominant negative interference with endogenous phyA activity in continuous far-red light, suggesting that the two photoreceptors may share reaction partners. INTRODUCTIONPhytochromes are the best characterized of the photoreceptors that control many aspects of early seedling development. These molecules are dimers with a monomeric molecular mass of 4 2 5 kD. Each monomer consists of two major structural domains: a chromophore-bearing, globular N-terminal domain (Vierstra and Quail, 1986) and an extended C-terminal domain, which carries the dimerization sites (Jones et al., 1986;Vierstra et al., 1987;Edgerton and Jones, 1992;Cherry et al., 1993).In Arabidopsis, the phytochromes are encoded by five different genes-PHYA through PHYE (Sharrock and Quail, 1989;Clack et al., 1994). Contrasting photosensory functions of the phyA and phyB holoproteins have been defined through analysis of responses to constitutive overexpression of Quail, 1989, 1991;Kay et al., 1989;Keller et al., 1989;Cherry et al., 1991;Wagner et al., 1991;McCormac et al., 1993) and mutations in (Nagatani et al., 1991(Nagatani et al., , 1993Somers et al., 1991;Dehesh et al., 1993;Parks and Quail, 1993;Reed et al., 1993;Whitelam et al., 1993;Wagner and Quail, 1995;Xu et al., 1995) hypocotyl elongation, hook opening, and cotyledon expansion) in continuous far-red light (FRc), whereas phyB is primarily responsible for deetiolation in continuous red light (Rc). phyA is most abundant in dark-grown seedlings (m50-fold phyB levels), whereas, due ...

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“…The N-terminal extension domain (NTE; Neff et al, 2000) contains several Ser residues in phyA, which are subject to phosphorylation (Lapko et al, 1997(Lapko et al, , 1999. Experiments performed on modified phyA carrying Ser/Ala substitutions or deletions in the NTE proved that this region is necessary for correct intracellular localization, biological activity, and signal attenuation (Cherry et al, 1992;Stockhaus et al, 1992;Jordan et al, 1996Jordan et al, , 1997Casal et al, 2002;Trupkin et al, 2007).…”

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confidence: 99%

Missense Mutation in the Amino Terminus of Phytochrome A Disrupts the Nuclear Import of the Photoreceptor

et al. 2011

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Phytochromes are the red/far-red photoreceptors in higher plants. Among them, phytochrome A (PHYA) is responsible for the far-red high-irradiance response and for the perception of very low amounts of light, initiating the very-low-fluence response. Here, we report a detailed physiological and molecular characterization of the phyA-5 mutant of Arabidopsis (Arabidopsis thaliana), which displays hyposensitivity to continuous low-intensity far-red light and shows reduced very-low-fluence response and high-irradiance response. Red light-induced degradation of the mutant phyA-5 protein appears to be normal, yet higher residual amounts of phyA-5 are detected in seedlings grown under low-intensity far-red light. We show that (1) the phyA-5 mutant harbors a new missense mutation in the PHYA amino-terminal extension domain and that (2) the complex phenotype of the mutant is caused by reduced nuclear import of phyA-5 under low fluences of far-red light. We also demonstrate that impaired nuclear import of phyA-5 is brought about by weakened binding affinity of the mutant photoreceptor to nuclear import facilitators FHY1 (for FAR-RED ELONGATED HYPOCOTYL1) and FHL (for FHY1-LIKE). Finally, we provide evidence that the signaling and degradation kinetics of constitutively nuclear-localized phyA-5 and phyA are identical. Taken together, our data show that aberrant nucleo/cytoplasmic distribution impairs light-induced degradation of this photoreceptor and that the amino-terminal extension domain mediates the formation of the FHY1/FHL/PHYA far-redabsorbing form complex, whereby it plays a role in regulating the nuclear import of phyA.

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Serine-to-alanine substitutions at the amino-terminal region of phytochrome A result in an increase in biological activity.

Cited by 109 publications

References 20 publications

Phytochrome Phosphorylation Modulates Light Signaling by Influencing the Protein–Protein Interaction[W]

Phytochrome Phosphorylation Modulates Light Signaling by Influencing the Protein–Protein Interaction[W]

Two Small Spatially Distinct Regions of Phytochrome B Are Required for Efficient Signaling Rates.

Missense Mutation in the Amino Terminus of Phytochrome A Disrupts the Nuclear Import of the Photoreceptor

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