Chromophore-bearing NH2-terminal domains of phytochromes A and B determine their photosensory specificity and differential light lability.

Wagner, Doris; Fairchild, Craig D.; Kuhn, Robert M.; Quail, Peter H.

doi:10.1073/pnas.93.9.4011

Cited by 72 publications

(70 citation statements)

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“…Alternatively, dimerization may be required for phyB activity because this phyB derivative is monomeric. Lastly, deletion of a proposed signal transducing (regulatory) region localized on the C-terminal domain may be responsible for loss of activity in AC652 Wagner and Quail, 1995;Wagner et al, 1996). The latter hypothesis predicts that a construct that retains this regulatory region, but deletes the remainder of the C-terminal domain (including the dimerization sites), should be biologically active.…”

Section: Discussion N-terminal and C-terminal Domains Of Phyb Are Reqmentioning

confidence: 99%

“…Possible reasons for the requirement of the contiguous presence of both domains include the necessity for signal transfer from the N-terminal to the C-terminal domain of phyB before signal transfer from the C-terminal domain to the cellular interaction partner of phyB (Wagner et al, 1996).…”

Section: Discussion N-terminal and C-terminal Domains Of Phyb Are Reqmentioning

confidence: 99%

“…In addition, a deletion derivative of phyA (AN52), which is the equivalent of AN90 of phyB, was found to show dominant negative interference in FRc but not in Rc (Boylan et al, 1994), indicating the importance of the deleted sequence to phyA activity specifically in FRc. Moreover, photosensory specificity of phyA and phyB has been mapped to the N-terminal domain of both photoreceptors (Wagner et al, 1996). Thus, the N-terminal extension of phyB is a good candidate for a region required for phyB-specific activity.…”

Section: N-terminal Extension Of Phyb Is Important For Normal Signalimentioning

confidence: 99%

“…Mutational analysis of phyA identified a region overlapping with both the region deleted in 8652-712 and the region identified for phyB as important for phyA regulatory activity xu et al, 1995). Lastly, analysis of chimeric phyA-phyB constructs has shown that the phyB C-terminal domain can functionally replace the phyA C-terminal domain and vice versa (Wagner et al, 1996), indicating that in the context of the fulllength molecule, the C-terminal domain is functionally equivalent in both photoreceptors. Taken together, these data strongly suggest that the small region at the N-terminal end of the C-terminal domain is important for the regulatory activity of both phyA and phyB.…”

Section: A Small Central Region May Be Lmportant For Signal Transfer mentioning

confidence: 99%

“…Accumulating evidence suggests that differential-photosensory specificity is due directly to the differences in primary structure of phyA and phyB rather than to differential expression of the two photoreceptors (Somers and Quaíl, 1995;Wagner et al, 1996). Thus, structural analysis of phyB may identify elements required specifically for phyB activity and/or regions required for activity of both photoreceptors.…”

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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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Section: Discussion N-terminal and C-terminal Domains Of Phyb Are Reqmentioning

confidence: 99%

Section: Discussion N-terminal and C-terminal Domains Of Phyb Are Reqmentioning

confidence: 99%

Section: N-terminal Extension Of Phyb Is Important For Normal Signalimentioning

confidence: 99%

Section: A Small Central Region May Be Lmportant For Signal Transfer mentioning

confidence: 99%

mentioning

confidence: 99%

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

1996

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Light Regulation and Biological Clocks

Millar¹,

Whitelam

Anderson³

et al. 2018

Annual Plant Reviews Online

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The Phytochromes

Tu¹,

Lagarias²

2008

Protein Science Encyclopedia

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Originally published in: Handbook of Photosensory Receptors. Edited by Winslow R. Briggs and John L. Spudich. Copyright © 2005 Wiley‐VCH Verlag GmbH & Co. KGaA Weinheim. Print ISBN: 3‐527‐31019‐7 The sections in this article are Introduction Photomorphogenesis and Phytochromes The Central Dogma of Phytochrome Action Molecular Properties of Eukaryotic and Prokaryotic Phytochromes Molecular Properties of Plant Phytochromes Molecular Properties of Cyanobacterial Phytochromes Photochemical and Nonphotochemical Conversions of Phytochrome The Phytochrome Chromophore Phytochrome Photointerconversions Dark Reversion Phytochrome Biosynthesis and Turnover Phytobilin Biosynthesis in Plants and Cyanobacteria Ferredoxin‐dependent Heme Oxygenases Ferredoxin‐dependent Phytobilin Synthases (Bilin Reductases) Apophytochrome Biosynthesis and Holophytochrome Assembly Apophytochrome Biosynthesis Holophytochrome Assembly Phytochrome Turnover Molecular Mechanism of Phytochrome Signaling: Future Perspective Regulation of Protein‐Protein Interactions by Phosphorylation Regulation of Tetrapyrrole Metabolism Acknowledgements

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Chromophore-bearing NH2-terminal domains of phytochromes A and B determine their photosensory specificity and differential light lability.

Abstract: In early seedling development, far-red-lightinduced deetiolation is mediated primarily by phytochrome A (phyA), whereas red-light-induced deetiolation is mediated primarily by phytochrome B (phyB). To

Cited by 72 publications

References 36 publications

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

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

Light Regulation and Biological Clocks

The Phytochromes

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