PT  - JOURNAL ARTICLE
AU  - Paween Mahinthichaichan
AU  - Dylan M. Morris
AU  - Yi Wang
AU  - Grant J. Jensen
AU  - Emad Tajkhorshid
TI  - Selective Permeability of Carboxysome Shell Pores to Anionic Molecules
AID  - 10.1101/367714
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 367714
4099  - http://biorxiv.org/content/early/2018/07/11/367714.short
4100  - http://biorxiv.org/content/early/2018/07/11/367714.full
AB  - Carboxysomes are closed polyhedral cellular microcompartments that increase the efficiency of carbon fixation in autotrophic bacteria. Carboxysome shells consist of small proteins that form hexameric units with semi-permeable central pores containing binding sites for anions. This feature is thought to selectively allow access to RuBisCO enzymes inside the carboxysome by (the dominant form of CO2 in the aqueous solution at pH 7.4) but not O2, which leads to a non-productive reaction. To test this hypothesis, here we use molecular dynamics simulations to characterize the energetics and permeability of CO2, O2, and through the central pores of two different shell proteins, namely, CsoS1A of α–carboxysome and CcmK4 of β-carboxysome shells. We find that the central pores are in fact selectively permeable to anions such as , as predicted by the model.