What are Carboxysomes?

About Carboxysomes:

• These are intracellular structures found in many autotrophic bacteria, including Cyanobacteria, Knallgasbacteria, Nitroso- and Nitrobacteria.
• They are proteinaceous structures resembling phage heads in their morphology; they contain the enzymes of carbon dioxide fixation in these organisms.
• Similar structures are known to harbor the B12-containing coenzyme glycerol dehydratase, the key enzyme of glycerol fermentation to 1,3-propanediol, in some Enterobacteriaceae, such as Salmonella.
• They perform carbon fixation, which is the process of converting carbon dioxide from the atmosphere into organic compounds that can be used by the cell for growth and energy. 
• These are made of polyhedral protein shells about 80 to 140 nanometres in diameter.
• These compartments are thought to concentrate carbon dioxide to overcome the inefficiency of RuBisCo (ribulose bisphosphate carboxylase/oxygenase) – the predominant enzyme in carbon fixation and the rate limiting enzyme in the Calvin cycle.

Application

• One of the most promising application of carboxysome is in plant synthetic biology, whereby the introduction of carboxysome into plant chloroplasts as the CO2-concentrating mechanism can improve photosynthetic efficiency and crop yield.

Q1: What is Carbon fixation?

It is the conversion of atmospheric carbon dioxide into organic molecules by autotrophic organisms. Because atmospheric inorganic carbon must be mobilized into organic compounds for life on earth.

Source: Researchers shed new light on carboxysomes in key discovery that could boost photosynthesis