Team:Bielefeld-CeBiTec/Project/CO2-fixation/Carboxysome

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The protein shell consists of two different types of proteins. Pentamers are used for the vertices of the icosaeder and hexamers for the facets. Carboxysomes are between 80 and 120 nm in diamter (<a href="#bonacci2011">Bonacci et al., 2011</a>). In the interior, there are two different types of enzymes. On the one hand there is the RuBisCO which catalyses the carboxylation oder oxygenation of ribulose-1,5-bisphosphate. On the other hand there is the carbonic anhydrase which converts hydrogen carbonate (HCO3<sup>-</sup>) to carbon dioxide. The resulting carbon dioxide is the substrate for the RuBisCO.<br>
The protein shell consists of two different types of proteins. Pentamers are used for the vertices of the icosaeder and hexamers for the facets. Carboxysomes are between 80 and 120 nm in diamter (<a href="#bonacci2011">Bonacci et al., 2011</a>). In the interior, there are two different types of enzymes. On the one hand there is the RuBisCO which catalyses the carboxylation oder oxygenation of ribulose-1,5-bisphosphate. On the other hand there is the carbonic anhydrase which converts hydrogen carbonate (HCO3<sup>-</sup>) to carbon dioxide. The resulting carbon dioxide is the substrate for the RuBisCO.<br>
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Generally, there are two different types of CBs found, called &alpha-type oder &beta-type carboxysomes. This classification is based on the coding sequence of the RuBisCo. &alpha-type carboxysomes
The advantage of the microcompartiment is that the concentration of carbon dioxide inside can be much higher than outside which increases the efficiency of the RuBisCO.<br>
The advantage of the microcompartiment is that the concentration of carbon dioxide inside can be much higher than outside which increases the efficiency of the RuBisCO.<br>
There are two different types of carboxysomes which are classified by the habitat of the organism. It is found in all cyanobacteria and some chemolitoautotrophic bacteria. A deletion mutant for a single gene of the cluster results in a conditionally lethal phenotype which requires high concentrations of carbon dioxide.</p>
There are two different types of carboxysomes which are classified by the habitat of the organism. It is found in all cyanobacteria and some chemolitoautotrophic bacteria. A deletion mutant for a single gene of the cluster results in a conditionally lethal phenotype which requires high concentrations of carbon dioxide.</p>

Revision as of 23:54, 14 October 2014


CO2 Fixation

Carboxysome

Carboxysome

A carboxysome is a bacterial microcompartiment (BMC) surrounded by a protein shell. Carboxysomes (CB) play an essential role in carbon fixation mechanism, as they are the seperated, enzym-containing center for these metabolic pathways.(Bonacci et al., 2011) (Shively et al., 1973) The first carboxysomes were discovered in 1956, and purified carboxysomes were first characterized in 1973 by Shively et al., 1973. Carboxysomes, as BMCs, are formed by different shell proteins, surrounding an enzyme-containing lumen, which is rigoroues seperated from the cytoplasm. Thus, the possibility is given to enable reaction pathways incongruous with the cytoplasm. The protein shell consists of two different types of proteins. Pentamers are used for the vertices of the icosaeder and hexamers for the facets. Carboxysomes are between 80 and 120 nm in diamter (Bonacci et al., 2011). In the interior, there are two different types of enzymes. On the one hand there is the RuBisCO which catalyses the carboxylation oder oxygenation of ribulose-1,5-bisphosphate. On the other hand there is the carbonic anhydrase which converts hydrogen carbonate (HCO3-) to carbon dioxide. The resulting carbon dioxide is the substrate for the RuBisCO.
Generally, there are two different types of CBs found, called &alpha-type oder &beta-type carboxysomes. This classification is based on the coding sequence of the RuBisCo. &alpha-type carboxysomes The advantage of the microcompartiment is that the concentration of carbon dioxide inside can be much higher than outside which increases the efficiency of the RuBisCO.
There are two different types of carboxysomes which are classified by the habitat of the organism. It is found in all cyanobacteria and some chemolitoautotrophic bacteria. A deletion mutant for a single gene of the cluster results in a conditionally lethal phenotype which requires high concentrations of carbon dioxide.

References

  • Bonacci et al., 2011. Modularity of carbon-fixing protein organelle. PNAS, vol. 109, pp. 478-483
  • Shively et al., 1973. Functional organelles in Prokaryotes: Polyhedral Inclusions (Carboxysomes) of Thiobacillus neapolitanus. Science, vol. 182, pp. 584-586