Protein phosphorylation in isolated nuclei from etiolated <i>Avena</i> seedlings Effects of red/far‐red light and cholera toxin

Romero, Luís C.; Biswal, Basanti; Song, Pill‐Soon

doi:10.1016/0014-5793(91)80510-a

Cited by 43 publications

(23 citation statements)

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“…There have been several reports suggesting that the phosphorylation0dephosphorylation of a number of proteins is mediated by the phytochrome phototransformation~Gallagher et Otto & Schäfer, 1988;Park & Chae, 1989;Romero et al, 1991;Doshi et al, 1992!. For example, phytochrome samples from irradiated seedlings have a higher phosphate content as compared to the samples from nonirradiated tissue~Lapko et al, 1996!.…”

Section: Posttranslational Modifications In Oat Phyamentioning

confidence: 99%

Mass spectrometric characterization of oat phytochrome A: Isoforms and posttranslational modifications

et al. 1999

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At least four mRNAs for oat phytochrome A~phyA! are present in etiolated oat tissue. The complete amino acid sequences of two phyA isoforms~A3 and A4! and the N-terminal amino acid sequence of a third isoform~A5! were deduced from cDNA sequencing~Hershey et al., 1985!. In the present study, heterogeneity of phyA on a protein level was studied by tryptic mapping using electrospray ionization mass-spectrometry~ESIMS!. The total tryptic digest of iodoacetamide-modified phyA was fractionated by gel filtration chromatography followed by reversed-phase highperformance liquid chromatography. ESIMS was used to identify peptides. Amino acid sequences of the peptides were confirmed or determined by collision-induced dissociation mass spectrometry~CID MS!, MS0MS, or by subdigestion of the tryptic peptides followed by ESIMS analysis. More than 97% of the phyA3 sequence~1,128 amino acid residues! was determined in the present study. Mass-spectrometric analysis of peptides unique to each form showed that phyA purified from etiolated oat seedling is represented by three isoforms A5, A3, and A4, with ratio 3.4:2.3:1.0. Possible light-induced changes in phytochrome in vivo phosphorylation site at Ser7~Lapko VN et al., 1997, Biochemistry 36:10595-10599! as well at Ser17 and Ser598~known as in vitro phosphorylation sites! were also analyzed. The extent of phosphorylation at Ser7 appears to be the same for phyA isolated from dark-grown and red-light illuminated seedlings. In addition to Ser7, Ser598 was identified as an in vivo phosphorylation site in oat phyA. Ser598 phosphorylation was found only in phyA from the red light-treated seedlings, suggesting that the protein phosphorylation plays a functional role in the phytochrome A-mediated light-signal transduction.

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Section: Posttranslational Modifications In Oat Phyamentioning

confidence: 99%

Mass spectrometric characterization of oat phytochrome A: Isoforms and posttranslational modifications

et al. 1999

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“…Since the visual transduction cascade in rod photoreceptor cells represents a classical model system for GPCR signaling [13], this well-understood signaling pathway has promoted researchers to investigate a similar role of G-proteins in the light sensing of plants. The early experiments to test this hypothesis were conducted with two adenosine diphos-npg phate (ADP)-ribosylating drugs, namely, the cholera toxin that constitutively activates the G-protein pathway and the pertussis toxin that switches off the G-protein signaling pathway [14][15][16][17]. Similarly, two chemical agents, GTPγs (a Gα-subunit activator) and GDPβs (a Gα-subunit inhibitor), have also been used in the study of the G-protein signaling pathway [18,19].…”

Section: Introductionmentioning

confidence: 99%

Heterotrimeric G-protein is involved in phytochrome A-mediated cell death of Arabidopsis hypocotyls

Wei

Zhou

et al. 2008

Cell Res

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The heterotrimeric guanine nucleotide-binding protein (G-protein) has been demonstrated to mediate various signaling pathways in plants. However, its role in phytochrome A (phyA) signaling remains elusive. In this study, we discover a new phyA-mediated phenotype designated far-red irradiation (FR) preconditioned cell death, which occurs only in the hypocotyls of FR-grown seedlings following exposure to white light (WL). The cell death is mitigated in the Gα mutant gpa1 but aggravated in the Gβ mutant agb1 in comparison with the wild type (WT), indicative of antagonistic roles of GPA1 and AGB1 in the phyA-mediated cell-death pathway. Further investigation indicates that FR-induced accumulation of nonphotoconvertible protochlorophyllide (Pchlide 633 ), which generates reactive oxygen species (ROS) on exposure to WL, is required for FR-preconditioned cell death. Moreover, ROS is mainly detected in chloroplasts using the fluorescent probe. Interestingly, the application of H 2 O 2 to dark-grown seedlings results in a phenotype similar to FR-preconditioned cell death. This reveals that ROS is a critical mediator for the cell death. In addition, we observe that agb1 is more sensitive to H 2 O 2 than WT seedlings, indicating that the G-protein may also modify the sensitivity of the seedlings to ROS stress. Taking these results together, we infer that the G-protein may be involved in the phyA signaling pathway to regulate FR-preconditioned cell death of Arabidopsis hypocotyls. A possible mechanism underlying the involvement of the G-protein in phyA signaling is discussed in this study.

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“…In etiolated pea seedlings, G-protein associated with plasma membranes was involved in blue-light signal transduction (Warpeha et al, 1991). The effect of red and far-red light on G-protein in oat seedlings was investigated by Romero et al (1991). They showed that the expression of phytochromeregulated genes, cab and phy, was affected by cholera toxin, an inhibitor of G-protein.…”

Section: Introductionmentioning

confidence: 99%

Nicotiana tabacum cDNAs encoding .ALPHA. and .BETA. subunits of a heterotrimeric GTP-binding protein isolated from hairy root tissues.

et al. 2000

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Protein phosphorylation in isolated nuclei from etiolated Avena seedlings Effects of red/far‐red light and cholera toxin

Cited by 43 publications

References 20 publications

Mass spectrometric characterization of oat phytochrome A: Isoforms and posttranslational modifications

Mass spectrometric characterization of oat phytochrome A: Isoforms and posttranslational modifications

Heterotrimeric G-protein is involved in phytochrome A-mediated cell death of Arabidopsis hypocotyls

Nicotiana tabacum cDNAs encoding .ALPHA. and .BETA. subunits of a heterotrimeric GTP-binding protein isolated from hairy root tissues.

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