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Team:TorontoMaRSDiscovery/Bioinformatics
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Background information:
Microcompartments:
Overview:
In nature, eukaryotic cells achieve different levels of organization by means of spatial segregation: proteins and chemicals are transported into and often retained within one of the many membrane-bound eukaryotic subcellular organelles, such as mitochondria, lysosomes, Golgi apparatus, etc. In bacteria, many cells can conditionally express proteinaceous microcompartments with similar function like eukaryotic organelles. These intracellular microcompartments are usually 100-150 nm in cross section [1]. They often consist of outer shells composed of thousands of protein subunits and functionally related enzymes in the core region[2]. This formation of microcompartment structure in bacteria allows cells to sequester specific metabolic pathways to enhance enzymatic efficiency and protect cells from the toxic effects of certain intermediates.
Classifications:
So far, most of our knowledge on bacterial microcompartments has been derived from the three well-studied microcompartment systems in nature.
- Carboxysomes:
- First reported in 1956, carboxysomes were the first bacteria microcompartments to be discovered. They are often present in cyanobacteria and other chemoautotrophic bacteria [3]. They are known to play a key role in enhancing autotrophic carbon fixation in the Calvin cycle. The shell of the carboxysome encodes the enzymes carbonic anhydrase (CA) and ribulose bis-phosphate carboxylase monooxygenase (RuBisCO). CA converts bicarbonate ions into carbon dioxide, which is then converted into 3-phosphoglycerate (3-PGA) by RuBisCO. Carboxysome not only allows for co-localization of CA and RuBisCO, but also acts as a diffusion barrier to retain carbon dioxide in the immediate vicinity of RuBisCO and thus catalyzes the conversion [2].
