T=75 icosahedral carboxysome

The carboxysome enhances CO2 fixation inside many photosynthetic and chemoautotrophic bacterial cells by encapsulating the key enzymes ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCO) and carbonic anhydrase. Interestingly this structure is icosahedral like viral capsid and has a T=75 symmetry .

T=75 icosahedral carboxysome is composed of 12 pentameric and 740 hexameric capsomeres for a total of 4500 carboxysome proteins.

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Icosahedric triangulation number is calculated following Caspar and Klug system

Viral molecular biology Virion
Virus entry
Virus latency
Transcription and replication
Host-virus interactions
Virus exit
Icosahedral capsids Virus symmetry and T number
T=1
T=2*
T=3
Pseudo T=3
T=4
T=7
T=9
T=13
T=16
T=21/pseudo T=21
T=25/pseudo T=25
T=27/pseudo T=27
T=28
T=31/pseudo T=31
T=75 bacterial carboxysome
T=169
Links Uniprot Keyword:
GO ontology:
Virus None
Bacteria cyanobacteria and some chemotrophic bacteria that fix carbon dioxide