We have developed an assay to monitor in vitro the posttranslational assembly of the chloroplast protein, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Most of the newly synthesized 55-kD catalytic ("large") subunits of this enzyme occur in a 29S complex together with 60- and 61-kD "binding" proteins. When the 29S complex is incubated with ATP and MgCl2 it dissociates into subunits...

RbcS antisense DNA mutants of tobacco have reduced amounts of ribulose bisphosphate carboxylase oxygenase (Rubisco). We found that carotenoid and chlorophyll contents decrease in parallel as Rubisco is decreased, however, pigment levels are not significantly altered until Rubisco levels are reduced sharply. The mutants have normal Chl a/Chl b ratios and normal plastid ultrastructures, suggestin...

The structure of active-site loop 6 plays a role in determining the CO2/O2 specificity of chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39). Rubisco from the green alga Chlamydomonas reinhardtii differs from higher plant Rubisco within the loop 6 region, and the C. reinhardtii enzyme has a CO2/O2 specificity 25% lower than that of higher plant enzymes. To examin...

A proteomic approach was used to analyze protein changes during nitrogen mobilization (N mobilization) from leaves to filling seeds in pea (Pisum sativum). First, proteome reference maps were established for mature leaves and stems. They displayed around 190 Coomassie Blue-stained spots with pIs from 4 to 7. A total of 130 spots were identified by mass spectrometry as corresponding to 80 differ...

Plants operating C3 and C4 photosynthetic pathways exhibit differences in leaf anatomy and photosynthetic carbon fixation biochemistry. Fully understanding this underpinning biochemical variation is requisite to identifying solutions for improving photosynthetic efficiency and growth. Here we refine assay methods for accurately measuring the carboxylase and decarboxylase activities in C3 and C4...

Ribulose bisphosphate carboxylase/oxygenase (Rubisco) is the protein that is responsible for the fixation of carbon dioxide in photosynthesis. Inhibitory sugar phosphate molecules, which can include its substrate ribulose-1,5-bisphosphate (RuBP), can bind to Rubisco catalytic sites and inhibit catalysis. These are removed by interaction with Rubisco activase (RA) via an ATP hydrolytic reaction....

The lysate from intact chloroplasts mechanically isolated from primary leaves of 9 day old seedlings of wheat (Triticum aestivum L. var Aoba) was incubated in the pH range of 5.5 to 8.5 at 37 degrees C for 5 hours. Proteolytic activity against ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) was estimated by disappearance of the large subunit of Rubisco or the appearance o...

A predictive and feedback glucose feed controller, previously developed for nutrient-sufficient growth of Escherichia coli to high cell densities, was used to produce large quantities of a heterologous, cyanobacterial recombinant hexadecameric (L8S8) protein, ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) in E. coli. Culture and plasmid stability conditions were optimized to yield th...

In cyanobacteria, the RbcX protein enhances the production of Rubisco, the multisubunit enzyme that catalyzes the first step of carbon dioxide fixation in most autotrophic organisms. In this issue of Cell, Saschenbrecker et al. (2007) report that RbcX acts as a specific assembly chaperone that mobilizes the large subunits of Rubisco to a specific oligomeric core that can then combine with the s...

The importance of the eukaryotic algal CO(2)-concentrating mechanism (CCM) is considered in terms of global productivity as well as molecular phylogeny and diversity. The three major constituents comprising the CCM in the majority of eukaryotes are described. These include: (i) likely plasma- and chloroplast-membrane inorganic carbon transporters; (ii) a suite of carbonic anhydrase enzymes in s...