Resonance Raman Analysis of Chromophore Structure in the Lumi-R Photoproduct of Phytochrome

Andel, Frank; Lagarias, J. Clark; Ra, Mathies

doi:10.1021/bi962175k

Cited by 114 publications

(155 citation statements)

References 51 publications

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“…The Pfr chromophore of phytochrome is in a distorted, high-energy C15-E, anticonfiguration, which is presumably maintained through chromophore-protein interactions (Andel et al, 1996). We speculate that the PHY domain contributes to the stability of the Pfr chromophore through such interactions.…”

Section: Phy Domain Function In Relation To the Spectral Properties Omentioning

confidence: 88%

Functional Analysis of a 450–Amino Acid N-Terminal Fragment of Phytochrome B in Arabidopsis

et al. 2004

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Phytochrome, a major photoreceptor in plants, consists of two domains: the N-terminal photosensory domain and the C-terminal domain. Recently, the 651-amino acid photosensory domain of phytochrome B (phyB) has been shown to act as a functional photoreceptor in the nucleus. The phytochrome (PHY) domain, which is located at the C-terminal end of the photosensory domain, is required for the spectral integrity of phytochrome; however, little is known about the signal transduction activity of this domain. Here, we have established transgenic Arabidopsis thaliana lines expressing an N-terminal 450-amino acid fragment of phyB (N450) lacking the PHY domain on a phyB-deficient background. Analysis of these plants revealed that N450 can act as an active photoreceptor when attached to a short nuclear localization signal and b-glucuronidase. In vitro spectral analysis of reconstituted chromopeptides further indicated that the stability of the N450 Pfr form, an active form of phytochrome, is markedly reduced in comparison with the Pfr form of full-length phyB. Consistent with this, plants expressing N450 failed to respond to intermittent light applied at long intervals, indicating that N450 Pfr is short-lived in vivo. Taken together, our findings show that the PHY domain is dispensable for phyB signal transduction but is required for stabilizing the Pfr form of phyB.

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Section: Phy Domain Function In Relation To the Spectral Properties Omentioning

confidence: 88%

Functional Analysis of a 450–Amino Acid N-Terminal Fragment of Phytochrome B in Arabidopsis

et al. 2004

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“…It has thus been difficult to predict how the domains in phytochrome might assemble, much less how light absorption results in signal transmission to the C-terminal portion of the protein. The structure of the chromophore in both Pr and Pfr states has also attracted considerable attention without a clear consensus; for example, the Pr chromophore has variously been proposed to adopt C5-Z,anti/C10-Z,syn/C15-Z,syn, C5-Z,anti/C10-Z,syn/C15-Z,anti, C5-Z,anti/C10-E,anti/C15-Z,syn, or C5-Z,syn/C10-Z,syn/C15-Z,anti conformations on the basis of vibrational spectroscopy and theoretical approaches (Andel et al, 1996(Andel et al, , 2000Kneip et al, 1999;Mroginski et al, 2004;Fischer et al, 2005; see http://www.iupac.org/publications/ compendium/index.html for conformational nomenclature).…”

Section: Structure and Assembly Of The Phytochrome Photosensory Corementioning

confidence: 99%

“…In this regard, the light-independent interconversion of Lumi-R to Pfr has been proposed to involve a further rotation about the C14,15 bond (Fodor et al, 1990;Andel et al, 1996;Kneip et al, 1999). This hypothesis requires that the Pfr chromophore would adopt a C15-E,syn conformation.…”

Section: Light Sensing and Signal Transduction: New Insightsmentioning

confidence: 99%

The Structure of Phytochrome: A Picture Is Worth a Thousand Spectra

2005

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“…However, in combination with other data, this structure provides a new basis for more directed speculation about the photochemical pathway than was possible without any experimental structure. Several Resonance Raman studies have led to proposal of a C15-E,anti geometry for the P fr chromophore, although without any consensus as to the structure of the P r chromophore (1,22,54,66,67,70). Examination of both Phys and Cph1 by FT-IR spectroscopy provides evidence that the primary photoproduct formed upon irradiation of P r , lumi-R, has a P fr -like configuration (23-25).…”

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confidence: 99%

Phytochrome Structure and Signaling Mechanisms

Rockwell

Lagarias

2006

Annu. Rev. Plant Biol.

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987

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Phytochromes are a widespread family of red/far-red responsive photoreceptors first discovered in plants, where they constitute one of the three main classes of photomorphogenesis regulators. All phytochromes utilize covalently attached bilin chromophores that enable photoconversion between red-absorbing (P r ) and far-red-absorbing (P fr ) forms. Phytochromes are thus photoswitchable photosensors; canonical phytochromes have a conserved N-terminal photosensory core and a Cterminal regulatory region which typically includes a histidine-kinase-related domain. The discovery of new bacterial and cyanobacterial members of the phytochrome family within the last decade has greatly aided biochemical and structural characterization of this family, with the first crystal structure of a bacteriophytochrome photosensory core appearing in 2005. This structure and other recent biochemical studies have provided exciting new insights into the structure of phytochrome, the photoconversion process that is central to light sensing, and the mechanism of signal transfer by this important family of photoreceptors. Keywordsphytochrome; biochemistry; biliprotein; photoreceptor; light signaling; photochemistry GENERAL INTRODUCTIONPhytochrome was first discovered in plants in 1959 as the photoreceptor that mediates plant growth and development in response to long-wavelength visible light (9). Phytochrome measures the ratio of red light (R) to far-red light (FR), thereby allowing the plant to assess the quantity of photosynthetically active light and trigger shade avoidance responses (89). Phytochromes are found in all flowering plants and cryptophytes, and this important family of developmental regulators constitutes one of the three major classes of photoreceptors in higher plants, with the others being cryptochromes and phototropins (3,8,91). *Corresponding author: Telephone: 530-752-1865; FAX: 530-752-3085; E-mail: jclagarias@ucdavis.edu. SIDE BAR Phytochromes as Sensors of Oxygen-Dependent Heme Catabolism. The bilin chromophores incorporated by all phytochromes are synthesized from heme in two steps. First, a heme oxygenase converts heme into BV, which is directly incorporated as the chromophore of BphP and Fph phytochromes. In plants and cyanobacteria, however, BV is further reduced to yield PΦB in higher plants and PCB in cyanobacteria and green algae. Conversion of BV to PΦB is carried out by HY-2 in the chloroplast, while reduction of BV to yield PCB is instead carried out by PcyA. Both HY-2 and PcyA belong to a conserved family of ferredoxin-dependent bilin reductases. The kinase activity and regulatory signaling state of many phytochromes are regulated not only by light but by the presence or absence of chromophore. The synthesis of chromophore is itself dependent on the heme metabolism of the cell, because chromophore will only be produced sparingly if cells are starved for heme or oxygen. Hence, phytochrome signaling is sensitive to heme metabolism and oxygen levels. Phytochromes therefore integrate both the light en...

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Resonance Raman Analysis of Chromophore Structure in the Lumi-R Photoproduct of Phytochrome

Cited by 114 publications

References 51 publications

Functional Analysis of a 450–Amino Acid N-Terminal Fragment of Phytochrome B in Arabidopsis

Functional Analysis of a 450–Amino Acid N-Terminal Fragment of Phytochrome B in Arabidopsis

The Structure of Phytochrome: A Picture Is Worth a Thousand Spectra

Phytochrome Structure and Signaling Mechanisms

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