The Carboxylation and Oxygenation of Ribulose 1,5-Bisphosphate: The Primary Events in Photosynthesis and Photorespiration

Lorimer, George H.

doi:10.1146/annurev.pp.32.060181.002025

Cited by 444 publications

(226 citation statements)

References 76 publications

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“…For Rubisco to act as a carboxylase and fix C, it must first be activated. One of the steps in activation involves carbamylation of the active site with a CO # molecule (Lorimer, 1981). Therefore, following the decline in stomatal conductance, and a reduction in the supply of internal CO # , it is possible that the amount of activated Rubisco declines, resulting in our observed reductions in V cmax .…”

Section: Fungal Impacts and Mechanismmentioning

confidence: 93%

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation

et al. 2000

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The following study investigates the timing and mechanism of impact of Swiss needle cast on Douglas-fir (Pseudotsuga menziesii) needle physiology (i.e. gas exchange). Swiss needle cast is a foliar disease caused by the fungus Phaeocryptopus gaeumannii, which occurs throughout the range of Douglas fir and until recently has been considered unimportant. However, recent surveys show the Swiss needle cast currently affects 52 611 ha of forested lands in western Oregon, USA, causing a reduction in growth of c. 23% or an implied growth loss of c. 3.2 m$ ha −" yr −" for 1996 alone. Gas exchange of artificially inoculated 2-yr-old Douglas-fir seedlings was monitored on a monthly basis using A\C i curve analysis. No effect of fungal presence on gas exchange was noted until the emergence of fungal fruiting structures (pseudothecia) from needle stomata. However, once present, maximum stomatal conductance and CO # assimilation rates were inversely proportional to the presence of pseudothecia. A\C i curve analysis showed that declines in CO # assimilation appeared to be due to both stomatal and nonstomatal limitations. Stomatal limitations to CO # assimilation were the direct result of reduced CO # diffusion through blocked stomata. Nonstomatal limitations arose, in part, from an indirect effect of pseudothecia development on Rubisco activation. For example, in both Swiss needle cast-infected foliage and foliage with artificially blocked stomata (by external application of petroleum jelly), the amount of Rubisco activation showed a strong, positive relationship with daily maximum stomatal conductance. A mechanism is proposed that outlines the impact of pseudothecia development on stomatal conductance and CO # assimilation rates.

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Section: Fungal Impacts and Mechanismmentioning

confidence: 93%

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation

et al. 2000

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“…In addition to being the substrate for photosynthetic carbon assimilation, CO, is an essential factor in the light-activation of the enzyme RuBP' carboxylase (14,18 …”

Section: Introductionmentioning

confidence: 99%

“…In addition to being the substrate for photosynthetic carbon assimilation, CO, is an essential factor in the light-activation of the enzyme RuBP' carboxylase (14,18). Results obtained with isolated enzyme preparations demonstrated that an activator CO2 molecule, which is not the substrate for CO2 fixation, forms an e-aminocarbamate with a lysyl residue located near the active site region (18).…”

mentioning

confidence: 99%

“…Results obtained with isolated enzyme preparations demonstrated that an activator CO2 molecule, which is not the substrate for CO2 fixation, forms an e-aminocarbamate with a lysyl residue located near the active site region (18). Because the carboxylase constitutes over onehalf the soluble protein in the stroma, the concentration of CO2 binding sites in the chloroplast exceeds 3 mm (14).…”

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confidence: 99%

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Characteristics of Light-Dependent Inorganic Carbon Uptake by Isolated Spinach Chloroplasts

Sicher¹

1984

Plant Physiol.

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The light-dependent accumulation of radioactively labeled inorganic carbon in isolated spinach (Spinacia orwcea L.) chloroplasts was determined by silicone oil filtering centrifuption. Intact chloroplasts, darkincubated 60 seconds at pH 7.6 and 23°C with 0.5 millimolar sodium bicarbonate, contained 0.5 to 1.0 millimolar internal inorganic carbon.The stromal pool of inorganic carbon increased 5-to 7-fold after 2 to 3 minutes of light. The saturated internal bicarbonate concentration of illuminated spinach chloroplasts was 10-to 20-fold greater than that of the external medium. This ratio decreased at lower temperatures and with increasing external bicarbonate. Over one-half the inorganic carbon found in intact spinach chloroplasts after 2 minutes of light was retained during a subsequent 3-minute dark incubation at 5'C. Calculations of light-induced stromal alkalization based on the uptake of radioactively labeled bicarbonate were OA to 0.5 pH units less than measurements performed with '4qCdimethyloxazolidine-dione. About one-third of the binding sites on the enzyme ribulose 1,5-bisphosphate carboxyase were radiolabeled when the enzyme was activated in situt and 4C02 bound to the activator site was trapped in the presence of carboxypentitol bisphosphates. Deleting orthophosphate from the incubation medium eliminated inorganic carbon accumulation in the stroma. Thus, bicarbonate ion distribution across the chloroplast envelope was not strictly pH dependent as predicted by the Henderson-Hasselbach formula. This finding is potentially explained by the presence of bound CO2 in the chloroplast.that illumination should produce a 10-fold increase of bicarbonate ion within this space. The following report details efforts in this laboratory to verify this observation.In addition to being the substrate for photosynthetic carbon assimilation, CO, is an essential factor in the light-activation of the enzyme RuBP' carboxylase (14,18 MATERIALS AND METHODSThe low ambient CO2 concentration in the atmosphere may be a critical factor limiting the photosynthetic rate of agronomic crop species (6). In spite of the importance of CO2 to the carbon assimilation process, there have been relatively few studies on the acquisition of inorganic carbon by isolated chloroplasts or by chloroplast envelope preparations (21,22,27). The transfer of inorganic carbon across the chloroplast membrane has been reviewed recently (8) and this process has the following important features: (a) permeability of the chloroplast envelope is high for CO2 relative to bicarbonate (27), (b) diffusion of CO2 across the chloroplast envelope is rapid and bicarbonate accumulation saturates in less than 30 s at 9C (21, 27), and (c) distribution of bicarbonate ion across the chloroplast envelope is dependent upon the pH gradient between the internal and external medium as predicted by the Henderson-Hasselbach equation (27). This latter observation is significant inasmuch as the internal and external bicarbonate ion concentrations can be used to calculate the ...

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“…Purified RuBPCase2 requires preincubation in Mg2" and CO2 before assay to attain maximal activity (for details, see reviews by Jensen and Bahr [6] and Lorimer [12] (14). This inability to deactivate the enzyme completely by eliminating CO2 has been observed previously with purified enzyme (13) (Fig.…”

mentioning

confidence: 99%

Activation State of Ribulose Bisphosphate Carboxylase in Soybean Leaves

Servaites¹,

Torisky²

1984

Plant Physiol.

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The Carboxylation and Oxygenation of Ribulose 1,5-Bisphosphate: The Primary Events in Photosynthesis and Photorespiration

Cited by 444 publications

References 76 publications

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation

Characteristics of Light-Dependent Inorganic Carbon Uptake by Isolated Spinach Chloroplasts

Activation State of Ribulose Bisphosphate Carboxylase in Soybean Leaves

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The Carboxylation and Oxygenation of Ribulose 1,5-Bisphosphate: The Primary Events in Photosynthesis and Photorespiration

Cited by 444 publications

References 76 publications

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO2 assimilation

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO2 assimilation

Characteristics of Light-Dependent Inorganic Carbon Uptake by Isolated Spinach Chloroplasts

Activation State of Ribulose Bisphosphate Carboxylase in Soybean Leaves

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Resources

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Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation

Pseudothecia of Swiss needle cast fungus, Phaeocryptopus gaeumannii, physically block stomata of Douglas fir, reducing CO₂ assimilation