Calcium-Modulated Proteins: Targets of Intracellular Calcium Signals in Higher Plants

Roberts, Daniel M.; Harmon, Alice C.

doi:10.1146/annurev.pp.43.060192.002111

Cited by 510 publications

(258 citation statements)

References 110 publications

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“…It is also likely that Ca 2ϩ , ionic strength and organic solvents induce conformational changes in was partially inhibited, and it suggests that LOR is activated by proteolysis. Enzymatic activation by limited proteolysis has the LOR domain of the enzyme, exposing hydrophobic plates on the surface of the protein, as has been shown for calmodulin been shown for many enzymes [29Ϫ33], including choline acetyltransferase (ChAT) which is activated fivefold by limited proand other Ca 2ϩ -binding proteins [28]. The Ca 2ϩ -dependent enhancement of LOR activity was inhibited by two structurally teolysis [29].…”

Section: Methodsmentioning

confidence: 99%

Structure and regulation of the bifunctional enzyme lysine‐oxoglutarate reductase‐saccharopine dehydrogenase in maize

Kemper

Cord-Neto

Capella

et al. 1998

European Journal of Biochemistry

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The lysine-oxoglutarate reductase (LOR) domain of the bifunctional enzyme lysine-oxoglutarate reductase-saccharopine dehydrogenase (LOR/SDH) from maize endosperm was shown to be activated by Ca 2ϩ , high salt concentration, organic solvents and Mg 2ϩ . The Ca 2ϩ -dependent enhancement of LOR activity was inhibited by the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) and calmidazolium. Limited proteolysis was used to assess the structure/function relationship of the enzyme. Digestion with elastase separated the bifunctional 125-kDa polypeptide into two polypeptides of 65 kDa and 57 kDa, containing the functional domains of LOR and SDH, respectively. Proteolysis did not affect SDH activity, while LOR showed a time-dependent and protease-concentration-dependent inactivation followed by reactivation. Prolonged digestion or increasing amounts of elastase produced a complex pattern of limit polypeptides derived from additional cleavage sites within the 65-kDa (LOR) and 57-kDa (SDH) domains. The SDH-containing polypeptides inhibited the enzymatic activity of LORcontaining polypeptides. When separated from the SDH domain by limited proteolysis and ion-exchange chromatography, the LOR domain retained its Ca 2ϩ activation property, but was no longer activated by high salt concentrations. These results suggest that the LOR activity of the native enzyme is normally inhibited such that after modulation, the enzyme undergoes a conformational alteration to expose the catalytic domain for substrate binding.

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Section: Methodsmentioning

confidence: 99%

Structure and regulation of the bifunctional enzyme lysine‐oxoglutarate reductase‐saccharopine dehydrogenase in maize

Kemper

Cord-Neto

Capella

et al. 1998

European Journal of Biochemistry

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“…Moreover, it can be argued that the proximal Ca 2ϩ -dependent effector in the signaling pathway may be similarly transiently activated, returning to its resting state when the activating Ca 2ϩ is removed. Signaling components such as the Ca 2ϩ -dependent protein kinases (55,56), calmodulin (57) and its responsive kinases (58,59), Ca 2ϩ -dependent phosphatases (60), Ca 2ϩ -gated channels (61), and Ca 2ϩ -activated phospholipases (62) are obvious candidates for this downstream effector.…”

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

confidence: 99%

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

Chandra

Low

1997

Journal of Biological Chemistry

146

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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“…Increased cytosolic calcium is believed to control biochemical and molecular processes by modulating the activity of specific proteins either directly or through calmodulin (1,2). Calmodulin, a highly conserved multifunctional calcium-binding protein, is implicated in many calcium-dependent cellular processes in plant and animal cells (2,5).…”

mentioning

confidence: 99%

“…To understand calmodulin-regulated processes, various strategies have been used to isolate, identify, and characterize the proteins that interact with calmodulin. These studies have resulted in identification of a few calmodulin-modulated proteins such as NAD kinase, calcium ATPase, nuclear nucleoside triphosphatase, a vacuolar ion channel, glutamate decarboxylase, elongation factor-1␣, and protein kinases in plants (1,(21)(22)(23)(24)(25)(26). Complementary DNAs that encode calmodulin-binding proteins of unknown function have also been isolated from maize and tobacco (27,28).…”

mentioning

confidence: 99%

A Novel Plant Calmodulin-binding Protein with a Kinesin Heavy Chain Motor Domain

Reddy

Safadi

Narasimhulu

et al. 1996

Journal of Biological Chemistry

169

155

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Calmodulin, a ubiquitous calcium-binding protein, regulates many diverse cellular functions by modulating the activity of the proteins that interact with it. Here, we report isolation of a cDNA encoding a novel kinesin-like calmodulin-binding protein (KCBP) from Arabidopsis using biotinylated calmodulin as a probe. Calcium-dependent binding of the cDNA-encoded protein to calmodulin is confirmed by 35

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Calcium-Modulated Proteins: Targets of Intracellular Calcium Signals in Higher Plants

Cited by 510 publications

References 110 publications

Structure and regulation of the bifunctional enzyme lysine‐oxoglutarate reductase‐saccharopine dehydrogenase in maize

Structure and regulation of the bifunctional enzyme lysine‐oxoglutarate reductase‐saccharopine dehydrogenase in maize

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

A Novel Plant Calmodulin-binding Protein with a Kinesin Heavy Chain Motor Domain

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