Wind-induced plant motion immediately increases cytosolic calcium.

Knight, Marc R.; Smith, Steven M.; Trewavas, Anthony

doi:10.1073/pnas.89.11.4967

Cited by 300 publications

(229 citation statements)

References 21 publications

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“…These findings suggest that GAD may be stimulated in vivo by Ca 2ϩ signal pathways. This hypothesis is consistent with data collected from studies demonstrating the rapid increase in cytoplasmic Ca 2ϩ concentrations (Knight et al, 1991(Knight et al, , 1992Price et al, 1994;Cholewa et al, 1997) and GABA titers (Wallace et al, 1984;Mayer et al, 1990;Cholewa et al, 1997) in plant cells upon exposure to various environmental stimuli.…”

supporting

confidence: 80%

“…This motif is common among PLP-requiring enzymes (Tanase et al, 1979). The identity and position of the Ser-X-X-Lys motif in the Arabidopsis GAD peptides are conserved with the motif in the products of the gadA and gadB genes from E. coli (Smith et al, 1992), which have been shown to require PLP for GAD activity, and the putative PLP sites of petunia GAD (Baum et al, 1993) and tomato GAD (Gallego et al, 1995). A putative CaM-binding region, located at the carboxy termini of the two peptides, was variable among the sequences.…”

Section: Sequence Analysis Of Gad Clonesmentioning

confidence: 99%

“…GAD is present in Escherichia coli (Smith et al, 1992), mammals (Erlander and Tobin, 1991), and plants (Satyanarayan and Nair, 1990). In plants the enzyme has a unique feature, a CaMbinding domain at the carboxy terminus (Baum et al, 1993;Arazi et al, 1995;Gallego et al, 1995).…”

mentioning

confidence: 99%

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Characterization of Two Glutamate Decarboxylase cDNA Clones from Arabidopsis

Turano

Fang

1998

Plant Physiology

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Two distinct cDNA clones encoding for the glutamate decarboxylase (GAD) isoenzymes GAD1 and GAD2 from Arabidopsis (L.) Heynh. were characterized. The open reading frames for GAD1 and GAD2 were expressed in Escherichia coli and the recombinant proteins were purified by affinity chromatography. Analysis of the recombinant proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis suggest that GAD1 and GAD2 encode for 58-and 56-kD peptides, respectively. The enzymatic activities of the pure recombinant GAD1 and GAD2 proteins were stimulated 35-and 13-fold, respectively, by Ca 2؉ /calmodulin but not by Ca 2؉ or calmodulin alone. Southern-blot analysis of genomic DNA suggests that there is only one copy of each gene in Arabidopsis. The GAD1 transcript and a corresponding 58-kD peptide were detected in roots only. Conversely, the GAD2 transcript and a corresponding 56-kD peptide were detected in all organs tested. The specific activity, GAD2 transcript, and 56-kD peptide increased in leaves of plants treated with 10 mM NH 4 Cl, 5 mM NH 4 NO 3 , 5 mM glutamic acid, or 5 mM glutamine as the sole nitrogen source compared with samples from plants treated with 10 mM KNO 3 . The results from these experiments suggest that in leaves GAD activity is partially controlled by gene expression or RNA stability. Results from preliminary analyses of different tissues imply that these tendencies were not the same in flower stalks and flowers, suggesting that other factors may control GAD activity in these organs. The results from this investigation demonstrate that GAD activity in leaves is altered by different nitrogen treatments, suggesting that GAD2 may play a unique role in nitrogen metabolism.

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supporting

confidence: 80%

Section: Sequence Analysis Of Gad Clonesmentioning

confidence: 99%

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Characterization of Two Glutamate Decarboxylase cDNA Clones from Arabidopsis

Turano

Fang

1998

Plant Physiology

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“…Ca 2ϩ fluxes in both the cell suspension cultures and whole seedlings were similarly inhibited by EGTA and La 3ϩ , and in both systems the magnitudes of the cold shocks and Ca 2ϩ transients were roughly proportional. Although physical barriers/inequities prevent similar comparisons of Ca 2ϩ transients following mechanical perturbation, elicitor stimulation, or osmotic stress, the observation that these signals also trigger Ca 2ϩ fluxes in both single cell and whole plant systems (38,39,50,51) adds further weight to the contention that cultured cells can serve as useful models when properly validated. With this motivation in mind, it should be possible to explore in greater detail the role of Ca 2ϩ pulses in signaling a variety of defenserelated responses.…”

Section: Fig 2 Effect Of Plant Defense Elicitors On Intracellular Cmentioning

confidence: 99%

“…Fortunately in 1991, Knight et al (38) transformed tobacco plants with a Ca 2ϩ -sensitive luminescent protein, termed aequorin, and demonstrated that resting levels of Ca 2ϩ were insufficient to induce photon emission but that stimulus-induced Ca 2ϩ increases generated readily measurable levels of bioluminescence. Since this initial discovery, aequorin-transformed plants have been exploited to quantitate intracellular Ca 2ϩ fluxes accompanying such diverse processes/ stimuli as direct mechanical perturbation (34,38), gusts of wind (39), cold shock (38,40), and circadian oscillations (30). Because the aequorin protein is expressed in the plant cell cytoplasm and because the intensity of light emitted by aequorin is directly proportional to Ca 2ϩ concentration, measurement of aequorin-derived bioluminescence enables direct quantitation of Ca 2ϩ transients in the transformed cytoplasm of the cell.…”

mentioning

confidence: 99%

Measurement of Ca2+ Fluxes during Elicitation of the Oxidative Burst in Aequorin-transformed Tobacco Cells

Chandra

Low

1997

Journal of Biological Chemistry

147

117

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We have employed suspension cultured aequorintransformed tobacco cells to examine the involvement of Ca 2؉ in signal transduction of the oxidative burst. Use of cultured cells for this purpose was validated by demonstrating that the cells responded to cold shock quantitatively and qualitatively similarly to the intact transgenic plants from which they were derived. Stimulation of the oxidative burst in the cell suspension was achieved by administration of oligogalacturonic acid, Mas-7 (a peptide known to activate G proteins and Ca 2؉ fluxes), hypo-osmotic stress, or harpin (a protein from the pathogenic bacterium Erwinia amylovora). The latter failed to promote any detectable increase in cytoplasmic Ca 2؉ concentration, whereas each of the former three triggered a rapid rise in cytosolic Ca 2؉ followed by a return within seconds to basal Ca 2؉ levels. Peak Ca 2؉ concentrations induced by the former three elicitors were ϳ0.7, 1.4, and 1.3 M, respectively. Three lines of evidence suggest that the observed Ca 2؉ pulses are essential to transduction of the oxidative burst signals by their respective elicitors: (i) inhibition of the Ca 2؉ transients with Ca 2؉ chelators or Ca 2؉ channel blockers prevented expression of the oxidative burst, (ii) introduction of exogenous Ca 2؉ into the same cells initiated the burst even in the absence of other inducers of the response, and (iii) the observed Ca 2؉ transients often returned to near basal levels well before any H 2 O 2 synthesis could be detected, suggesting that the Ca 2؉ influx is required to communicate the burst signal but not maintain the defense response. These data suggest that Ca 2؉ pulses serve frequently, but not invariably, to transduce an oxidative burst signal.The oxidative burst constitutes one of the more rapid responses of a plant cell to pathogen attack (1). Within minutes of pathogen recognition, reactive oxygen species are generated that may promote cross-linking and lignification of the cell wall (2, 3), transcription of defense-related genes (4, 5), secondary metabolite biosynthesis (6), the hypersensitive response (4,7,8), and direct pathogen cytotoxicity (9, 10), depending on the plant species examined. In cultured cell systems, the oxidative burst can be promoted by isolated elicitors including harpin (11, 12), oligouronides (13), elicitins (14), purified fungal peptides (15), and other molecules from the extracts of pathogens (7,16). Abiotic stimuli such as mechanical stress (17), the pesticide fenthion (18), cold shock (19), phosphatase inhibitors (4, 20), and hypo-osmotic stress (17) can also induce biosynthesis of reactive oxygen species in plant cells.Because of its rapid expression, ease of assay, and similarity to the analogous defense response in human neutrophils (21), the oxidative burst has recently served as a model for exploring signal transduction pathways in plants. As the numbers of elicitors examined have risen, it has become increasingly clear that different elicitors may inaugurate independent signal transduction pathways that...

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Comparative modeling of the three-dimensional structure of the calmodulin-related TCH2 protein from arabidopsis

et al. 1997

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Plants adapt to various stresses by developmental alterations that render them less easily damaged. Expression of the TCH2 gene of Arabidopsis is strongly induced by stimuli such as touch and wind. The gene product, TCH2, belongs to the calmodulin (CaM) family of proteins and contains four highly conserved Ca(2+)-binding EF-hands. We describe here the structure of TCH2 in the fully Ca(2+)-saturated form, constructed using comparative molecular modeling, based on the x-ray structure of paramecium CaM. Like known CaMs, the overall structure consists of two globular domains separated by a linker helix. However, the linker region has added flexibility due to the presence of 5 glycines within a span of 6 residues. In addition, TCH2 is enriched in Lys and Arg residues relative to other CaMs, suggesting a preference for targets which are more negatively charged. Finally, a pair of Cys residues in the C-terminal domain, Cys126 and Cys131, are sufficiently close in space to form a disulfide bridge. These predictions serve to direct future biochemical and structural studies with the overall aim of understanding the role of TCH2 in the cellular response of Arabidopsis to environmental stimuli.

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Wind-induced plant motion immediately increases cytosolic calcium.

Abstract: Wind

Cited by 300 publications

References 21 publications

Characterization of Two Glutamate Decarboxylase cDNA Clones from Arabidopsis

Characterization of Two Glutamate Decarboxylase cDNA Clones from Arabidopsis

Measurement of Ca2+ Fluxes during Elicitation of the Oxidative Burst in Aequorin-transformed Tobacco Cells

Comparative modeling of the three-dimensional structure of the calmodulin-related TCH2 protein from arabidopsis

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