Carboxysomes – Sequestering RubisCO for Efficient Carbon Fixation
Carbon fixation in cyanobacteria (and some chemoautotrophs) occurs in large cytoplasmic bodies known as carboxysomes. Carboxysomes are organized as an enzymatic core comprised of RubisCO and carbonic anhydrase, encapsulated within a thin protein shell. The carbonic anhydrase converts concentrated bicarbonate into carbon dioxide, which can then be fixed by RubisCO. The shell is required as it presents a semi-permeable barrier; in its absence, CO2 would escape too rapidly to allow efficient fixation. Despite the complexity of this arrangement, and large size of the resulting particle (90–400 nm), carboxysomes are self-organizing and require as few as eight different polypeptides (including the enzymes) for proper self-assembly. This chapter explores discusses the structure and functional roles of the proteins that build up the carboxysome, and analyses the unique architecture of these particles.
KeywordsCarbonic Anhydrase Active Carbonic Anhydrase Methanosarcina Thermophila Full Length Variant Zinc Binding Residue
– Bacterial microcompartment;
– Carbonic anhydrase;
– Doubled permuted bacterial microcompartment;
– Ethanolamine utilization microcompartment;
– Propanediol utilization microcompartment;
– Ribulose 1,5-bisphosphate;
– Ribulose 1,5-bisphosphate carboxylase/oxygenase
This work was funded by a Discovery Grant from the National Science and Engineering Research Council of Canada to MSK (# 327280).
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