The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are cur...

The developmental pattern of C4 expression has been well characterized in maize and other C4 plants. However, few reports have explored the possibility that the development of this pathway may be sensitive to changes in atmospheric CO2 concentrations. Therefore, both the structural and biochemical development of leaf tissue in the fifth leaf of Sorghum bicolor plants grown at elevated CO2 have ...

Arabidopsis Rubisco was activated in vitro at rates 2- to 3-fold greater by recombinant Arabidopsis 43-kD Rubisco activase with the amino acid replacements Q111E and Q111D in a phosphate-binding loop, G-G-K-G-Q-G-K-S. However, these two mutant enzymes had only slightly greater rates of ATP hydrolysis. Activities of the Q111D enzyme were much less sensitive and those of Q111E were somewhat less ...

Ribulose 1,5 bisphosphate carboxylase oxygenase (Rubisco) concentrations were quantified as a proportion of total protein in eight species of microalgae. This enzyme has been assumed to be a major fraction of total protein in phytoplankton, as has been demonstrated in plants, potentially constituting a large sink for cellular nitrogen. Representative microalgae were grown in batch and continuou...

BACKGROUND Cyanobacteria play a significant role in the global carbon cycle. In Synechococcuselongatus, the carbon-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is concentrated into polyhedral, proteinaceous compartments called carboxysomes. METHODOLOGY/PRINCIPAL FINDINGS Using live cell fluorescence microscopy, we show that carboxysomes are first detected as small s...

Many nutritive symbioses between chemoautotrophic bacteria and invertebrates, such as Solemya velum , have d 13 C values of ~30 to 35‰, considerably more depleted than phytoplankton. Most of the chemoautotrophic symbionts fix carbon with a form IA ribulose 1,5-bisphosphate carboxylase (RubisCO). We hypothesized that this form of RubisCO discriminates against 13 CO 2 to a greater extent than oth...

Genetic and environmental variation in carbon isotope discrimination (A), photosynthetic gas exchange, growth and activities of phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase (Rubisco) were studied in four sugarcane clones grown under three different irrigation regimes for 65 d in a greenhouse. A of the uppermost fully expanded leaf increased with decreasing ir...

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a crucial enzyme in carbon fixation and the most abundant protein on earth. It has been studied extensively by biochemical and structural methods; however, the most essential activation step has not yet been described. Here, we describe the mechanistic details of Lys carbamylation that leads to RuBisCO activation by atmospheric CO(2)....

The incorporation of newly synthesized large subunits into ribulose bisphosphate carboxylase/oxygenase (RuBisCO) in pea chloroplast extracts occurs at the expense of intermediate forms of the large subunit which are complexed with a binding protein. Most subunits of this binding protein are found in dodecameric complexes in chloroplast extracts. Addition of small subunits to these extracts resu...

Rubisco enzymes play central roles in carbon fixation, with potential importance in biotechnology, but have eluded a full description of their multistep assembly and function. A new article describes the fascinating discovery that some archaeal Rubiscos contain a built-in assembly domain inserted into an otherwise canonical Rubisco fold, providing a tremendous expansion of our understanding of ...