Limitation of the Rate of Ribulosebisphosphate Carboxylase Activation by Carbamylation and Ribulosebisphosphate Carboxylase Activase Activity: Development and Tests of a Mechanistic Model

1996 ◽  
Vol 23 (2) ◽  
pp. 141 ◽  
Author(s):  
IE Woodrow ◽  
ME Kelly ◽  
KA Mott
Keyword(s):  
Mechanistic Model ◽  
Large Subunit ◽  
Intercellular Co2 Concentration ◽  
Rubisco Activase ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Bisphosphate Carboxylase ◽  
Ribulosebisphosphate Carboxylase ◽  
Kinetics Of ◽  
Rubisco Activation

A mechanistically-based model of light-mediated activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is developed. The model describes the kinetics of Rubisco activation following a relatively rapid increase in photon flux density (PPFD) from an initially low level. Underlying the model is the assumption that there are two slow processes that could potentially limit the rate of light-mediated Rubisco activation. These processes are the addition of the activator CO2 to the large subunit of Rubisco, which is accompanied by a conformational change in the enzyme (carbamylation), and activase-mediated removal of ribulose 1,5-bisphosphate from the inactive form of the enzyme. The contribution of these slow processes to the overall activation kinetics of Rubisco was resolved by measuring Rubisco activation in whole spinach leaves using non-steady-state CO2 exchange. It was found that when the change in PPFD was relatively small and a correspondingly small proportion of the Rubisco pool was activated, the kinetics of activation were highly sensitive to the intercellular CO2 concentration (ci). The apparent rate constant for activation under these conditions was found to be similar to that for the carbamylation of purified spinach Rubisco. When the change in PPFD and the proportion of Rubisco activated was relatively large, however, the kinetics of Rubisco activation were almost completely CO2 insensitive and were consistent with those of an enzyme-catalysed reaction. It is suggested that (1) CO2-insensitive activation reflects the operation of Rubisco activase and (2) the increasing CO2 sensitivity seen as the change in PPFD decreases reflects a transition to limitation by carbamylation.

Comparison of the structure and function of ribulosebisphosphate carboxylase–oxygenase from a cold-hardy and nonhardy potato species

1981 ◽  
Vol 59 (4) ◽  
pp. 280-289 ◽  
Author(s):  
Norman P. A. Huner ◽  
Jiwan P. Palta ◽  
Paul H. Li ◽  
John V. Carter
Keyword(s):  
Large Subunit ◽  
Structure And Function ◽  
Sulfhydryl Groups ◽  
Relative Mass ◽  
Nitrobenzoic Acid ◽  
Significant Difference ◽  
Ribulosebisphosphate Carboxylase ◽  
Cold Hardy ◽  
And Function ◽  
Kinetics Of

A comparison of ribulosebisphosphate carboxylase–oxygenase from the leaves of the non-acclimated, cold-hardy species, Solanum commersonii, and the nonacclimated, nonhardy species, Solanum tuberosum showed that this enzyme from the two species differed in structure and function. The results of sulfhydryl group titration with 5,5′-dithiobis(2-nitrobenzoic acid) indicated that the kinetics of titration and the number of accessible sulfhydryl groups in the native enzymes were different. After 30 min, the enzyme from the hardy species had 1.7 times fewer sulfhydryl groups titrated than that from the nonhardy species. In the presence of 1% (w/v) sodium dodecyl sulfate, the total number of sulfhydryl groups titratable with 5,5′-dithiobis-(2-nitrobenzoic acid) was the same for both species. However, this denaturant had a differential effect on the kinetics of titration with 5,5′-dithiobis(2-nitrobenzoic acid). Both enzymes had a native molecular weight of about 550 000. The quaternary structures of the two enzymes were similar with the presence of large and small subunits of 54 000 and 14 000, respectively. However, there was more polypeptide of 108 000 – 110 000 present in preparations of the enzyme from S. tuberosum than from S. commersonii. This polypeptide is an apparent dimer of the large subunit on a relative mass basis. The large subunit of the enzyme from S. tuberosum was more sensitive to the absence of reducing agent and was more sensitive to freezing and thawing than the large subunit of the enzyme from S. commersonii. Catalytic properties of both enzymes at 5 and 25 °C indicated no significant difference in the [Formula: see text] at either temperature. However, the Vmax at 5 °C for the enzyme from S. commersonii was 35% higher than that of the enzyme from S. tuberosum. In contrast, the Vmax at 25 °C for the enzyme of the hardy species was 250% lower than that of the enzyme from the nonhardy species.

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.

scholarly journals Incorporation of carbon from photosynthetic products into 2-carboxyarabinitol-1-phosphate and 2-carboxyarabinitol

1994 ◽  
Vol 304 (3) ◽  
pp. 781-786 ◽  
Author(s):  
P J Andralojc ◽  
G W Dawson ◽  
M A J Parry ◽  
A J Keys
Keyword(s):  
Specific Binding ◽  
Anion Exchange Chromatography ◽  
Photosynthetic Photon Flux Density ◽  
French Bean ◽  
Exchange Chromatography ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Bisphosphate Carboxylase ◽  
Naturally Occurring ◽  
Subsequent Exposure

The synthesis of 2-carboxy-D-arabinitol-1-phosphate (CA1P), the naturally occurring inhibitor of ribulose-1,5-bisphosphate carboxylase/oxygenase, was studied in leaves of the French bean Phaseolus vulgaris, L. Leaves were supplied with air containing 14CO2 in the light then the plants were transferred to normal air in the light or in the dark. Leaf samples were frozen in liquid nitrogen, ground to a powder and extracted with acid. Lipids, pigments and cations were removed from the extract and CA1P and 2-carboxy-D-arabinitol (CA) recovered by anion exchange chromatography. The CA1P was further purified by its specific binding to purified ribulose-1,5-bisphosphate carboxylase/oxygenase. CA and CA1P were identified by chromatographic properties and n.m.r. spectra. When plants were kept for 15 h in darkness after exposure to 14CO2, up to 2.2% and 5.5% of the radioactivity in the extracts was present in CA1P and CA, respectively. The most radioactivity appeared in these compounds when photosynthesis from 14CO2 took place at low photosynthetic photon flux density (PPFD). Under such conditions, radioactivity was detected in CA1P after only 10 min. During subsequent exposure to normal air (12CO2) at low PPFD the amount of radioactivity in CA1P remained almost constant for 6 h; in darkness the rate of incorporation of radioactivity into CA1P reached a maximum after 2 h and the radioactivity was still increasing 6 h later. At low PPFD, the amount of CA1P in the leaves reached a maximum after 2 h. In darkness, the amount of CA1P began to increase rapidly after a lag of almost 1 h, well ahead of the increase in radioactivity in CA1P.

scholarly journals Photosynthetic responses of young cashew plants to varying environmental conditions

2005 ◽  
Vol 40 (8) ◽  
pp. 735-744 ◽  
Author(s):  
Rogéria Pereira de Souza ◽  
Rafael Vasconcelos Ribeiro ◽  
Eduardo Caruso Machado ◽  
Ricardo Ferraz de Oliveira ◽  
Joaquim Albenísio Gomes da Silveira
Keyword(s):  
Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Co2 Assimilation ◽  
Photon Flux ◽  
Photochemical Quenching ◽  
Photon Flux Density ◽  
Effective Quantum Yield ◽  
Water Losses ◽  
Controlled Conditions

The aim of this study was to characterize gas exchange responses of young cashew plants to varying photosynthetic photon flux density (PPFD), temperature, vapor-pressure deficit (VPD), and intercellular CO2 concentration (Ci), under controlled conditions. Daily courses of gas exchange and chlorophyll a fluorescence parameters were measured under natural conditions. Maximum CO2 assimilation rates, under optimal controlled conditions, were about 13 mmol m-2 s-1 , with light saturation around 1,000 mmol m-2 s-1. Leaf temperatures between 25ºC and 35ºC were optimal for photosynthesis. Stomata showed sensitivity to CO2, and a closing response with increasing Ci. Increasing VPD had a small effect on CO2 assimilation rates, with a small decrease above 2.5 kPa. Stomata, however, were strongly affected by VPD, exhibiting gradual closure above 1.5 kPa. The reduced stomatal conductances at high VPD were efficient in restricting water losses by transpiration, demonstrating the species adaptability to dry environments. Under natural irradiance, CO2 assimilation rates were saturated in early morning, following thereafter the PPFD changes. Transient Fv/Fm decreases were registered around 11h, indicating the occurrence of photoinhibition. Decreases of excitation capture efficiency, decreases of effective quantum yield of photosystem II, and increases in non-photochemical quenching were consistent with the occurrence of photoprotection under excessive irradiance levels.

Changes in the heterogeneity of ribulosebisphosphate carboxylase–oxygenase in winter rye induced by cold hardening

1982 ◽  
Vol 60 (9) ◽  
pp. 897-903 ◽  
Author(s):  
N. P. A. Huner ◽  
D. B. Hayden
Keyword(s):  
Large Subunit ◽  
Cold Hardening ◽  
Winter Rye ◽  
Charge Heterogeneity ◽  
Two Dimensional Gel Electrophoresis ◽  
Bisphosphate Carboxylase ◽  
Ribulose 1 ◽  
Ribulosebisphosphate Carboxylase ◽  
Quaternary Structures ◽  
Molecular Weight Heterogeneity

The quaternary structures of ribulose-1, 5-bisphosphate carboxylase–oxygenase from cold-hardened and unhardened Puma rye were examined by two-dimensional gel electrophoresis according to the method of O'Farrell. The results indicate that major changes in charge heterogeneity occur in the large subunit of this enzyme during growth at cold-hardening temperatures. The extent of charge heterogeneity decreased upon adaptation of Puma rye to cold-hardening temperatures. In addition to charge heterogeneity, molecular weight heterogeneity was also evident in the large subunit polypeptides of the enzyme from cold-hardened and unhardened Puma rye.

Structural Properties and Ribulosebisphosphate Carboxylase and Oxygenase Activity of Fraction-1 Protein from the Marine Alga Halimeda cylindracea (Chlorophyta)

1976 ◽  
Vol 3 (1) ◽  
pp. 93 ◽  
Author(s):  
T Akazawa ◽  
CB Osmond
Keyword(s):  
Large Subunit ◽  
Homogeneous State ◽  
Plant Type ◽  
Precipitation Line ◽  
Carboxylase Activity ◽  
Bisphosphate Carboxylase ◽  
Subunit A ◽  
Fraction 1 Protein ◽  
Oxygenase Activity ◽  
Ribulosebisphosphate Carboxylase

Ribulosebisphosphate carboxylase/oxygenase activity was detected in Halimeda cylindracea and Chaetomorpha crassa. In H. cylindracea carboxylase activity (72-250 micromoles CO2 fixed per hour per milligram chlorophyll) was sufficient to account for measured photosynthetic rates. The activity of the oxygenase was only 1 % that of the carboxylase but otherwise both enzymes showed properties similar to those of the same enzymes in higher green plants. Fraction-1 protein from H. cylindracea was purified to a homogeneous state as tested by poly- acrylamide gel electrophoresis at pH 8.9. The activity of the ribulose-1,5-bisphosphate carboxylase in the purified preparations was 0.1 micromoles CO2 fixed per minute per milligram protein (pH 7.0). The H. cylindracea fraction-1 protein was shown to comprise two subunits, A and B, with molecular weights 5.4 × 104, and 1.35 x 104, respectively, typical of the plant-type ribulose-1,5-bisphosphate carboxylase. The amino acid composition of the large subunit A was similar to that from spinach and Chlorella enzymes, whereas that of the subunit B was markedly distinguishable from the enzymes of other origins. The close resemblance of the H. cylindricea protein to the plant enzymes was further supported by the formation of a spur in the double immunodiffusion precipitation line, indicating probable existence of sequence-homology of the catalytic larger subunit A, typical of the plant-type enzyme molecules.

Kinetics of Rubisco Activation as Determined from Gas-exchange Measurements in Antisense Plants of Arabidopsis thaliana Containing Reduced Levels of Rubisco Activase

1997 ◽  
Vol 24 (6) ◽  
pp. 811 ◽  
Author(s):  
Keith A. Mott ◽  
Gordon W. Snyder ◽  
Ian E. Woodrow
Keyword(s):  
Arabidopsis Thaliana ◽  
Steady State ◽  
Gas Exchange ◽  
Rubisco Activase ◽  
Activation Rate ◽  
Time Courses ◽  
Activation Rates ◽  
Kinetics Of ◽  
Rubisco Activation ◽  
Intercellular Co2

The kinetics of the increase in photosynthesis rate following an increase in PFD were determined in wildtype Arabidopsis thaliana plants and in two antisense plants that contained reduced levels of Rubisco activase. Experiments were conducted over a range of intercellular CO2 mole fractions (ci). The rate at which photosynthesis approached steady-state following an increase in PFD was similar for wildtype and transformed plants at low values of ci. At higher values of ci, however, wildtype plants approached steady state more rapidly than did the antisense plants. Photosynthesis time courses were used to calculate Rubisco activation rates for the three types of plants, and Rubisco activation rate was found to be proportional to activase content at a ci of 280 µmol mol-1. These data are discussed in the context of proposed mechanisms for Rubisco activase in the activation of Rubisco.

Variations in photosynthetic, anatomical, and enzymatic leaf traits and correlations with growth in recently selected Populus hybrids

1987 ◽  
Vol 17 (4) ◽  
pp. 273-283 ◽  
Author(s):  
R. Ceulemans ◽  
I. Impens ◽  
V. Steenackers
Keyword(s):  
Growth Performance ◽  
Principal Component ◽  
Net Photosynthesis ◽  
Leaf Traits ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Ribulose Bisphosphate Carboxylase ◽  
Bisphosphate Carboxylase ◽  
Shoot Height

Several photosynthetic, anatomical, and enzymatic leaf traits were studied on 1- and 2-year-old fast growing Populus clones representing interspecific hybrids of P. deltoides, P. trichocarpa, and P. maximowiczii. Growth performance of the clones was studied with container-grown plants and for 5 years in the field. Considerable variation in photosynthetic, anatomical, and enzymatic leaf traits was found, but variation in growth differences among the clonal groups was minimal. Photosynthetic photon flux density saturated net photosynthesis of 1-year-old container-grown plants was significantly correlated with shoot height growth, but none of the other leaf traits measured showed a significant correlation with any of the growth characteristics. Clonal groups could be segregated by taxonomic and genetic affinities with hierarchical clustering and principal component analysis. Although enzymatic and biochemical traits (area leaf weight, ribulose-bisphosphate carboxylase and phosphoenolpyruvate carboxylase activities, protein content) and adaxial stomatal frequency can be used to discriminate among clonal groups, no significant regression of these leaf traits on growth performance was observed.

scholarly journals Rubisco activase requires residues in the large subunit N terminus to remodel inhibited plant Rubisco

2020 ◽  
Vol 295 (48) ◽  
pp. 16427-16435
Author(s):  
Jediael Ng ◽  
Zhijun Guo ◽  
Oliver Mueller-Cajar
Keyword(s):  
Higher Plants ◽  
Large Subunit ◽  
Rubisco Activase ◽  
Higher Plant ◽  
Bisphosphate Carboxylase ◽  
Interaction Sites ◽  
Dead End ◽  
Highly Sensitive ◽  
N Terminus ◽  
Sugar Phosphates

The photosynthetic CO2 fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) forms dead-end inhibited complexes while binding multiple sugar phosphates, including its substrate ribulose 1,5-bisphosphate. Rubisco can be rescued from this inhibited form by molecular chaperones belonging to the ATPases associated with diverse cellular activities (AAA+ proteins) termed Rubisco activases (Rcas). The mechanism of green-type Rca found in higher plants has proved elusive, in part because until recently higher-plant Rubiscos could not be expressed recombinantly. Identifying the interaction sites between Rubisco and Rca is critical to formulate mechanistic hypotheses. Toward that end here we purify and characterize a suite of 33 Arabidopsis Rubisco mutants for their ability to be activated by Rca. Mutation of 17 surface-exposed large subunit residues did not yield variants that were perturbed in their interaction with Rca. In contrast, we find that Rca activity is highly sensitive to truncations and mutations in the conserved N terminus of the Rubisco large subunit. Large subunits lacking residues 1–4 are functional Rubiscos but cannot be activated. Both T5A and T7A substitutions result in functional carboxylases that are poorly activated by Rca, indicating the side chains of these residues form a critical interaction with the chaperone. Many other AAA+ proteins function by threading macromolecules through a central pore of a disc-shaped hexamer. Our results are consistent with a model in which Rca transiently threads the Rubisco large subunit N terminus through the axial pore of the AAA+ hexamer.

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