<i>Arabidopsis</i>phytochromes C and E have different spectral characteristics from those of phytochromes A and B

Eichenberg, Klaus; Bäurle, Isabel; Paulo, Nicola; Sharrock, Robert A.; Rüdiger, Wolfhart; Schäfer, Eberhard

doi:10.1016/s0014-5793(00)01301-6

Cited by 80 publications

(68 citation statements)

References 46 publications

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“…2). The wavelengths of ⌬ min and ⌬ max were consistent with those reported (43), indicating that synthetic bilins were reconstituted with the apoprotein and were identical with the natural one extracted from algae.…”

Section: Resultssupporting

confidence: 85%

“…Hence, characterization of the molecular interaction between the chromophore and the apoprotein is crucial for understanding the functional mechanism(s) of phytochromes. Several studies have addressed this interaction by using in vitro assembly of PHYA (5,28,29,47), PHYB (35,37,48), PHYC and PHYE (43), or apoprotein mutants (30)(31)(32). However, in contrast to the vertebrate photoreceptor rhodopsin (49), in the phytochrome field, little has been done to examine the relationships among chromophore structure, its assembly to apoprotein, and photochromism of the holoprotein, because of the difficulty of synthesizing the chromophore and its structural analogs.…”

Section: Discussionmentioning

confidence: 99%

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In vitro assembly of phytochrome B apoprotein with synthetic analogs of the phytochrome chromophore

Hanzawa

Inomata

Kinoshita

et al. 2001

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

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Phytochrome B (PhyB), one of the major photosensory chromoproteins in plants, mediates a variety of light-responsive developmental processes in a photoreversible manner. To analyze the structural requirements of the chromophore for the spectral properties of PhyB, we have designed and chemically synthesized 20 analogs of the linear tetrapyrrole (bilin) chromophore and reconstituted them with PhyB apoprotein (PHYB). The A-ring acts mainly as the anchor for ligation to PHYB, because the modification of the side chains at the C2 and C3 positions did not significantly influence the formation or difference spectra of adducts. In contrast, the side chains of the B-and C-rings are crucial to position the chromophore properly in the chromophore pocket of PHYB and for photoreversible spectral changes. The side-chain structure of the D-ring is required for the photoreversible spectral change of the adducts. When methyl and ethyl groups at the C17 and C18 positions are replaced with an n-propyl, n-pentyl, or n-octyl group, respectively, the photoreversible spectral change of the adducts depends on the length of the side chains. From these studies, we conclude that each pyrrole ring of the linear tetrapyrrole chromophore plays a different role in chromophore assembly and the photochromic properties of PhyB.

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Section: Resultssupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

In vitro assembly of phytochrome B apoprotein with synthetic analogs of the phytochrome chromophore

Hanzawa

Inomata

Kinoshita

et al. 2001

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

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“…Alternatively, phyE might act as an additional photoreceptor for FR. In this regard, it is noteworthy that a recent report described profound differences between the photochemical properties of phyB and phyE (Eichenberg et al, 2000). Further investigations will be required to resolve this issue.…”

Section: Phye Is Required For Germination In Continuous Fr But Not Fomentioning

confidence: 94%

Phytochrome E Controls Light-Induced Germination of Arabidopsis

Hennig¹

2002

Plant Physiology

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Germination of Arabidopsis seeds is light dependent and under phytochrome control. Previously, phytochromes A and B and at least one additional, unspecified phytochrome were shown to be involved in this process. Here, we used a set of photoreceptor mutants to test whether phytochrome D and/or phytochrome E can control germination of Arabidopsis. The results show that only phytochromes B and E, but not phytochrome D, participate directly in red/far-red light (FR)-reversible germination. Unlike phytochromes B and D, phytochrome E did not inhibit phytochrome A-mediated germination. Surprisingly, phytochrome E was required for germination of Arabidopsis seeds in continuous FR. However, inhibition of hypocotyl elongation by FR, induction of cotyledon unfolding, and induction of agravitropic growth were not affected by loss of phytochrome E. Therefore, phytochrome E is not required per se for phytochrome A-mediated very low fluence responses and the high irradiance response. Immunoblotting revealed that the need of phytochrome E for germination in FR was not caused by altered phytochrome A levels. These results uncover a novel role of phytochrome E in plant development and demonstrate the considerable functional diversification of the closely related phytochromes B, D, and E.In many plants, seed germination is light dependent . Among plant photoreceptors, only phytochromes have been shown to directly mediate induction of germination. Recently, several new insights into the molecular mechanisms of phytochrome action and its physiological role throughout the whole life cycle of plants were achieved (for review, see Whitelam and Devlin, 1997;Casal, 2000; Smith, 2000). In Arabidopsis, phytochrome is a small gene family, consisting of the five members, PHYA to PHYE (Sharrock and Quail, 1989;Clack et al., 1994). PHYB, PHYD, and PHYE are evolutionary related and clearly separated from PHYA and PHYC (Mathews and Sharrock., 1997). Studies using mutants and overexpressor lines demonstrated that individual phytochrome family members have overlapping and distinct functions (Reed et al., 1994; Smith et al., 1997). phyA and phyB are the best characterized phytochromes in Arabidopsis. phyA mediates the high irradiance response in far red light (FR; FR-HIR) and the very low fluence response (VLFR), which can also be induced by FR. In contrast, phyB mediates the red light (R)/FR-reversible low fluence response (LFR;. Less is known about the other phytochromes. An LFR-type action of phyD could be observed in phyB seedlings (Aukerman et al., 1997;Hennig et al., 1999a). The high sequence identity of phyB and phyD (Ͼ80%) suggests very similar roles of these two phytochromes, albeit certain physiological differences have been reported (Hennig et al., 1999a). Finally, for phyE, mainly functions in the shade avoidance syndrome of adult plants have been described (Devlin et al., 1996(Devlin et al., , 1998. Furthermore, phyE has been shown to be capable of signaling to the circadian clock in seedlings (Devlin and Kay, 2000).Light-induced germ...

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“…The PHYB/E split occurred early in the history of living angiosperms and was followed by an episode of selection at PHYE, acting on one site in the GAF loop and on one site in a9, the long helix connecting the GAF and PHY domains ( Figure 3C). The GAF loop residue lies between two oat phyA mutants, both of which lead to an 8-nm blue shift (Kim et al, 2007); thus, it is possible that the PHYE change at this position contributed to the blue shift in the absorption maximum of PHYE relative to that of PHYB (Eichenberg et al, 2000a). The split between PHYB and PHYE occurred early in the history of living angiosperms, since PHYE is present in Austrobaileyales but has not been detected in water lilies or Amborella; however, this episode of selection cannot be precisely placed since full-length PHYE sequences are available from eudicots only.…”

Section: Changes On the Be B And E Branchesmentioning

confidence: 99%

Evolutionary Studies Illuminate the Structural-Functional Model of Plant Phytochromes

Mathews

2010

The Plant Cell

107

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A synthesis of insights from functional and evolutionary studies reveals how the phytochrome photoreceptor system has evolved to impart both stability and flexibility. Phytochromes in seed plants diverged into three major forms, phyA, phyB, and phyC, very early in the history of seed plants. Two additional forms, phyE and phyD, are restricted to flowering plants and Brassicaceae, respectively. While phyC, D, and E are absent from at least some taxa, phyA and phyB are present in all sampled seed plants and are the principal mediators of red/far-red-induced responses. Conversely, phyC-E apparently function in concert with phyB and, where present, expand the repertoire of phyB activities. Despite major advances, aspects of the structural-functional models for these photoreceptors remain elusive. Comparative sequence analyses expand the array of locus-specific mutant alleles for analysis by revealing historic mutations that occurred during gene lineage splitting and divergence. With insights from crystallographic data, a subset of these mutants can be chosen for functional studies to test their importance and determine the molecular mechanism by which they might impact light perception and signaling. In

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Arabidopsisphytochromes C and E have different spectral characteristics from those of phytochromes A and B

Cited by 80 publications

References 46 publications

In vitro assembly of phytochrome B apoprotein with synthetic analogs of the phytochrome chromophore

In vitro assembly of phytochrome B apoprotein with synthetic analogs of the phytochrome chromophore

Phytochrome E Controls Light-Induced Germination of Arabidopsis

Evolutionary Studies Illuminate the Structural-Functional Model of Plant Phytochromes

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