scholarly journals Phosphorylation of phosphoenolpyruvate carboxykinase in plants. Studies in plants with C4 photosynthesis and Crassulacean acid metabolism and in germinating seeds

1996 ◽  
Vol 317 (3) ◽  
pp. 653-658 ◽  
Author(s):  
Robert P. WALKER ◽  
Richard C. LEEGOOD
Keyword(s):  
Molecular Mass ◽  
Crassulacean Acid Metabolism ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Acid Metabolism ◽  
C4 Photosynthesis ◽  
C4 Grasses ◽  
Cam Plants ◽  
Sds Page ◽  
Germinating Seeds

We have previously shown that phosphoenolpyruvate carboxykinase (PEPCK) is phosphorylated in vivo in the cotyledons of darkened cucumber seedlings and that phosphorylation is reversed by light [Walker and Leegood (1995) FEBS Lett. 362, 70–74]. In this study the molecular mass of PEPCK was estimated in a range of gluconeogenic seedlings and in leaves of C4 plants and plants with Crassulacean acid metabolism (CAM). Phosphorylation of PEPCK was studied in these plants by feeding tissues with [32P]Pi and assessing phosphorylation by SDS/PAGE and autoradiography of either total proteins or of immunoprecipitated protein. In gluconeogenic seedlings and most CAM plants PEPCK had a molecular mass of 74 kDa, whereas in C4 grasses the molecular mass of PEPCK was always smaller and varied from 67–71 kDa. In all gluconeogenic seedlings and leaves of CAM plants PEPCK was phosphorylated, but it was not phosphorylated in all species of C4 grasses studied. In CAM plants, phosphorylation of PEPCK occurred at night and dephosphorylation occurred during the day. In C4 grasses phosphorylation occurred when leaves were darkened and the enzyme was dephosphorylated following illumination, but it was only phosphorylated in those plants with larger (71 kDa) molecular mass forms of PEPCK.

Are crassulacean acid metabolism and C4 photosynthesis incompatible?

2002 ◽  
Vol 29 (6) ◽  
pp. 775 ◽  
Author(s):  
Rowan F. Sage
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
C4 Photosynthesis ◽  
Bundle Sheath ◽  
C4 Plants ◽  
Cam Plants ◽  
Bundle Sheath Cells ◽  
C4 Pathway ◽  
Cam Species ◽  
Cam Photosynthesis

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Despite sharing a similar metabolism, crassulacean acid metabolism (CAM) and C4 photosynthesis are not known to occur in identical species, with the exception of Portulaca spp. In Portulaca, C4 and weak CAM photosynthesis occur in distinct regions of the leaf, rather than in the same cells. This is in marked contrast to the situation in most CAM species where C3 and CAM photosynthesis are active in the same cell over the course of a day and growing season. The lack of CAM and C4 photosynthesis in identical cells of a plant indicates these photosynthetic pathways are incompatible. Incompatibilities between CAM and C4 photosynthesis could have a number of biochemical, anatomical and evolutionary explanations. Biochemical incompatibilities could result from the requirement for spatial separation of C3 and C4 phases in C4 plants versus temporal separation in CAM plants. In C4 plants, regulatory systems coordinate mesophyll and bundle sheath metabolism, with light intensity being the major environmental signal. In CAM plants, a circadian oscillator coordinates day and night phases of CAM. The requirement for rapid intercellular transport in C4 plants may be incompatible with the intracellular transport and storage needs of CAM. For example, the large vacuole required for malate storage in CAM could impede metabolite diffusion between mesophyll and bundle sheath cells in C4 plants. Anatomical barriers could also exist because both CAM and the C4 pathway require distinct leaf anatomies for efficient function. Efficient function of the C4 pathway generally requires an outer layer of cells specialized for phosphoenolpyruvate (PEP) carboxylation and regeneration and an inner layer for CO2 accumulation and refixation, while CAM species require enlarged vacuoles and tight cell packing. In evolutionary terms, barriers preventing CAM and C4 photosynthesis in the same species may be the initial steps in the respective evolutionary pathways from C3 ancestors. The first steps in C4 photosynthesis are related to scavenging photorespiratory CO2 via localization of glycine decarboxylase in the bundle sheath cells. The initial steps in CAM evolution are associated with the scavenging of respiratory CO2 at night by PEP carboxylation. In each, simplified versions of the specialized anatomy may need to be present for the evolutionary sequence to begin. For C4 evolution, enhanced bundle sheath size may be required in C3 ancestors; for CAM evolution, succulence may be required. Thus, before CAM or C4 photosynthesis began to evolve, the outcome of the evolutionary experiment may have been predetermined.

Phosphoenolpyruvate Carboxykinase in C4 Plants: Its Role and Regulation

1997 ◽  
Vol 24 (4) ◽  
pp. 459 ◽  
Author(s):  
Robert P. Walker ◽  
Richard M. Acheson ◽  
László I. Técsi ◽  
Richard C. Leegood
Keyword(s):  
Molecular Mass ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
C4 Plants ◽  
Panicum Maximum ◽  
C4 Plant ◽  
Cam Plants ◽  
Crude Extracts ◽  
High Concentrations ◽  
Regulatory Properties

Some of the recent findings which revise our view of the role and regulation of phosphoenolpyruvate carboxykinase (PEPCK) in C4 plants are discussed. Evidence is presented that PEPCK is present at appreciable activities in the bundle-sheath of some NADP-malic enzyme-type C4 plants, such as maize, but it was not detectable in NAD-malic enzyme-type C4 plants. PEPCK is rapidly inactivated in crude extracts of leaves of the C4 plant, Panicum maximum. This inactivation could be prevented by high concentrations of dithiothreitol or by the inclusion of ADP or ATP, suggesting the involvement of thiols at the active site. PEPCK is also subject to rapid proteolysis in crude extracts of a range of C4 plants, resulting in cleavage to a smaller (62 kDa) form. This can be reduced by extraction at high pH and by the inclusion of SDS, but it means that intact PEPCK has never been purified from a C4 plant. The molecular mass of PEPCK varies considerably in C4 plants, unlike C3 and CAM plants in which it is usually 74 kDa. PEPCK is phosphorylated during darkness (and reversed by light) in some C4 plants with PEPCK of a larger molecular mass, such as Panicum maximum (71 kDa), but it was not phosphorylated in the PEPCK-type C4 plant, Sporobolus pyramidalis (69 kDa). The known regulatory properties of PEPCK are discussed in relation to its role in C4 photosynthesis, in particular its sensitivity to regulation by adenylates and by Mn2+.

Regulation of malic-acid metabolism in Crassulacean-acid-metabolism plants in the dark and light: In-vivo evidence from 13C-labeling patterns after 13CO2 fixation

Planta ◽  
1988 ◽  
Vol 175 (2) ◽  
pp. 184-192 ◽  
Author(s):  
C. B. Osmond ◽  
J. A. M. Holtum ◽  
M. H. O'Leary ◽  
C. Roeske ◽  
O. C. Wong ◽  
...  
Keyword(s):  
Malic Acid ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
13C Labeling

Short-term plasticity of crassulacean acid metabolism expression in the epiphytic bromeliad Tillandsia usneoides

2002 ◽  
Vol 29 (6) ◽  
pp. 749 ◽  
Author(s):  
Richard Haslam ◽  
Anne Borland ◽  
Howard Griffiths
Keyword(s):  
Phase I ◽  
Carbon Balance ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Rapid Change ◽  
Co2 Uptake ◽  
Short Term Plasticity ◽  
Non Invasive ◽  
Tillandsia Usneoides

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The regulation and flexibility of the crassulacean acid metabolism (CAM) pathway has been investigated in the 'extreme epiphyte' Tillandsia usneoides (L.). Submerging strands of T. usneoides under water, thereby inhibiting the supply of atmospheric CO2, allowed non-invasive in vivo manipulation of the supply of CO2 during the nocturnal Phase I of CAM. Once the plants were removed from submersion, T. usneoides maintained open stomata, and net CO2 uptake occurred throughout most of the photoperiod. Variability in the expression of CAM allowed T. usneoides to compensate for restricted CO2 availability through Phase I of CAM by adjusting gas exchange rates through the photoperiod and subsequent dark period to maintain a constant internal supply of CO2 in the light. Furthermore, T. usneoides demonstrated a gradual, rather than rapid, change in phosphoenolpyruvate carboxylase (PEPC) activation across the day-night cycle, such that PEPC and Rubisco appear to work in tandem in order to maintain carbon balance for this extreme atmospheric bromeliad.

How to tell the time: the regulation of phosphoenolpyruvate carboxylase in Crassulacean acid metabolism (CAM) plants

2003 ◽  
Vol 31 (3) ◽  
pp. 728-730 ◽  
Author(s):  
H.G. Nimmo
Keyword(s):  
Circadian Rhythms ◽  
Phosphoenolpyruvate Carboxylase ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Circadian Oscillator ◽  
Cam Plants ◽  
Reversible Phosphorylation ◽  
Circadian Expression ◽  
Phosphoenolpyruvate Carboxylase Kinase ◽  
Co2 Metabolism

Crassulacean acid metabolism (CAM) plants exhibit persistent circadian rhythms of CO2 metabolism. These rhythms are driven by changes in the flux through phosphoenolpyruvate carboxylase, which is regulated by reversible phosphorylation in response to a circadian oscillator. This article reviews progress in our understanding of the circadian expression of phosphoenolpyruvate carboxylase kinase.

scholarly journals Light-responsive expression atlas reveals the effects of light quality and intensity in Kalanchoë fedtschenkoi, a plant with crassulacean acid metabolism

GigaScience ◽  
2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Jin Zhang ◽  
Rongbin Hu ◽  
Avinash Sreedasyam ◽  
Travis M Garcia ◽  
Anna Lipzen ◽  
...  
Keyword(s):  
Light Intensity ◽  
White Light ◽  
Crassulacean Acid Metabolism ◽  
Light Quality ◽  
Acid Metabolism ◽  
Easy Access ◽  
Cam Plants ◽  
A Genome ◽  
Acid Accumulation ◽  
Expression Atlas

Abstract Background Crassulacean acid metabolism (CAM), a specialized mode of photosynthesis, enables plant adaptation to water-limited environments and improves photosynthetic efficiency via an inorganic carbon-concentrating mechanism. Kalanchoë fedtschenkoi is an obligate CAM model featuring a relatively small genome and easy stable transformation. However, the molecular responses to light quality and intensity in CAM plants remain understudied. Results Here we present a genome-wide expression atlas of K. fedtschenkoi plants grown under 12 h/12 h photoperiod with different light quality (blue, red, far-red, white light) and intensity (0, 150, 440, and 1,000 μmol m–2 s–1) based on RNA sequencing performed for mature leaf samples collected at dawn (2 h before the light period) and dusk (2 h before the dark period). An eFP web browser was created for easy access of the gene expression data. Based on the expression atlas, we constructed a light-responsive co-expression network to reveal the potential regulatory relationships in K. fedtschenkoi. Measurements of leaf titratable acidity, soluble sugar, and starch turnover provided metabolic indicators of the magnitude of CAM under the different light treatments and were used to provide biological context for the expression dataset. Furthermore, CAM-related subnetworks were highlighted to showcase genes relevant to CAM pathway, circadian clock, and stomatal movement. In comparison with white light, monochrome blue/red/far-red light treatments repressed the expression of several CAM-related genes at dusk, along with a major reduction in acid accumulation. Increasing light intensity from an intermediate level (440 μmol m−2 s−1) of white light to a high light treatment (1,000 μmol m–2 s–1) increased expression of several genes involved in dark CO2 fixation and malate transport at dawn, along with an increase in organic acid accumulation. Conclusions This study provides a useful genomics resource for investigating the molecular mechanism underlying the light regulation of physiology and metabolism in CAM plants. Our results support the hypothesis that both light intensity and light quality can modulate the CAM pathway through regulation of CAM-related genes in K. fedtschenkoi.

scholarly journals CO2 starvation experiments provide support for the carbon-limited hypothesis on the evolution of CAM-like behaviour in Isoëtes

2020 ◽  
Vol 127 (1) ◽  
pp. 135-141
Author(s):  
Jacob S Suissa ◽  
Walton A Green
Keyword(s):  
Aquatic Ecosystems ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Selective Pressure ◽  
Atmospheric Co2 ◽  
Terrestrial Plants ◽  
Cam Plants ◽  
Acid Accumulation ◽  
Use Efficiency ◽  
Nocturnal Acid Accumulation

Abstract Background and Aims Crassulacean acid metabolism (CAM) is an adaptation to increase water use efficiency in dry environments. Similar biochemical patterns occur in the aquatic lycophyte genus Isoëtes. It has long been assumed and accepted that CAM-like behaviour in these aquatic plants is an adaptation to low daytime carbon levels in aquatic ecosystems, but this has never been directly tested. Methods To test this hypothesis, populations of Isoëtes engelmannii and I. tuckermanii were grown in climate-controlled chambers and starved of atmospheric CO2 during the day while pH was measured for 24 h. Key Results We demonstrate that terrestrial plants exposed to low atmospheric CO2 display diel acidity cycles similar to those in both xerophytic CAM plants and submerged Isoëtes. Conclusions Daytime CO2 starvation induces CAM-like nocturnal acid accumulation in terrestrial Isoëtes, substantiating the hypothesis that carbon starvation is a selective pressure for this physiological behaviour.

Cell organelles from crassulacean acid metabolism (CAM) plants

Planta ◽  
1980 ◽  
Vol 147 (5) ◽  
pp. 477-484 ◽  
Author(s):  
C. Schnarrenberger ◽  
D. Gro� ◽  
Ch. Burkhard ◽  
M. Herbert
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Cam Plants ◽  
Cell Organelles

Purification and Properties of Phosphoenolpyruvate Carboxylase From Plants With Crassulacean Acid Metabolism

1982 ◽  
Vol 9 (4) ◽  
pp. 409 ◽  
Author(s):  
DL Nott ◽  
CB Osmond
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Functional Significance ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Sodium Dodecyl ◽  
Kinetic Properties ◽  
Cam Plants ◽  
Pep Carboxylase ◽  
Purification And Properties ◽  
Ph Dependent

Phosphoenolpyruvate (PEP) carboxylase was purified from three species of crassulacean acid metabolism (CAM) plants. There was no evidence for isoenzymes of PEP carboxylase in these plants and the purified protein was an active dimer of Mr 220 000-250 000 which dissociated to a monomer of Mr 110 000 after treatment with sodium dodecyl sulfate. Active, higher aggregates could be obtained on Sepharose 6B but the functional significance, if any, of these remains to be assessed. In the absence of effectors, normal Michaelis-Menten kinetics were obtamed with the substrates HCO3- and PEP. The purified enzyme shows a preference for HCO3-, rather than CO2, at pH 6.1 and 8.1, with a Km (HCO3-) of 10-20 �M. The Vmax was relatively independent of pH between pH 5.5 and 8.5, but the Km (PEP) (like most other kinetic properties) was pH dependent with a minimum of about 0.1 mM PEP at pH 6.8. Malate inhibition was more effective at pH 6.2 than at pH 8.2, and the inhibition evidently involved a slow binding of malate which increased the Km (PEP) and resulted in non-hyperbolic kinetics. The Km (PEP) was lowered about 5-10-fold by 1.0 mM glucose 6-phosphate which also overcame malate inhibition and restored hyperbolic kinetic relationships in the presence of malate. Possible roles for these properties in the regulation of CAM are discussed.

Resistance is useful: diurnal patterns of photosynthesis in C3 and crassulacean acid metabolism epiphytic bromeliads

2002 ◽  
Vol 29 (6) ◽  
pp. 679 ◽  
Author(s):  
Kate Maxwell
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Enzyme Activation ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Cam Plants ◽  
Diurnal Patterns ◽  
Rubisco Activation

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001 Diurnal patterns of photosynthesis in response to environmental variables were investigated in an obligate C3 and a facultative C3-crassulacean acid metabolism (CAM) bromeliad species. A midday depression of photosynthesis occurred in both C3 groups, mediated as a decrease in stomatal conductance in response to increased vapour pressure difference. The response was associated with a reduction in Rubisco activation state during the period of maximum photon flux density. In contrast, the switch to CAM resulted in a strong shift in the pattern of Rubisco carbamylation, with full enzyme activation delayed until the midday period. For the first time it is demonstrated that the pattern of Rubisco activation differs between C3 and CAM plants of the same species under identical conditions. Despite large differences in Rubisco content between C3 and CAM plants, neither the amount of Rubisco or enzyme activity is thought to be limiting for photosynthesis, and it is suggested that Rubisco may function as a nitrogen store. Extreme CO2 diffusion limitation resulted in low rates of atmospheric CO2 assimilation that were associated with high rates of photosynthetic electron transport, and it is likely that photorespiration constitutes a significant electron sink over the entire diurnal course. Leaf morphological and physiological adaptations to drought stress are necessary for the epiphytic lifestyle but limit CO2 assimilation and confound the likelihood of high productivity.

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