Engineering CO2-Fixing Carboxysome into Saccharomyces cerevisiae to Improve Ethanol Production.

Abstract

Bacterial microcompartments (BMCs) are intracellular structures for compartmentalizing specific metabolic pathways in bacteria. As a unique type of BMCs, carboxysomes utilize protein shells to sequester ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase for efficient carbon dioxide (CO₂) fixation. This study aims to reconstruct an α-carboxysome in Saccharomyces cerevisiae and investigate its metabolic effects. Here, genes of the cso operon from Halothiobacillus neapolitanus, Calvin cycle-related enzyme phosphoribulokinase (PRK) from Spinacia oleracea, and two S. cerevisiae chaperone genes, HSP60 and HSP10, were introduced into S. cerevisiae. The engineered yeast strain demonstrated assembled and enzymatically active Rubisco, significant increase in ethanol production and reduction in the byproduct glycerol. Formation of the α-carboxysome structures was observed after purification by sucrose density gradient centrifugation. The engineered yeast strain harboring functional α-carboxysome has the potential for enhancing bioethanol production.