Halothiobacillus neapolitanus carboxysomes sequester heterologous and chimeric RubisCO species.
BACKGROUND
The carboxysome is a bacterial microcompartment that consists of a polyhedral protein shell filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO), the enzyme that catalyzes the first step of CO2 fixation via the Calvin-Benson-Bassham cycle.


RESULTS
To analyze the role of RubisCO in carboxysome biogenesis in vivo we have created a series of Halothiobacillus neapolitanus RubisCO mutants. We identified the large subunit of the enzyme as an important determinant for its sequestration into alpha-carboxysomes and found that the carboxysomes of H. neapolitanus readily incorporate chimeric and heterologous RubisCO species. Intriguingly, a mutant lacking carboxysomal RubisCO assembles empty carboxysome shells of apparently normal shape and composition.


CONCLUSIONS
These results indicate that carboxysome shell architecture is not determined by the enzyme they normally sequester. Our study provides, for the first time, clear evidence that carboxysome contents can be manipulated and suggests future nanotechnological applications that are based upon engineered protein microcompartments.
Menon
Balaraj B
BB
Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, Mississippi, USA.
Dou
Zhicheng
Z
Heinhorst
Sabine
S
Shively
Jessup M
JM
Cannon
Gordon C
GC
D015478:Antigens, Heterophile / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D022082:Cellular Structures / Q000378:metabolism* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D044222:Halothiobacillus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D030781:Organisms, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism*
D015478:Antigens, Heterophile; D011993:Recombinant Fusion Proteins; D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase