Construction of Osmotic Pressure Responsive Vacuole-like Bacterial Organelles with Capsular Polysaccharides as Building Blocks

Abstract

Many artificial organelles or subcellular compartments have been developed to tune gene expression, regulate metabolic pathways, or endow new cell functions. Most of these organelles or compartments were built using proteins or nucleic acids as building blocks. In this study, we demonstrated that capsular polysaccharide (CPS) retained inside bacteria cytosol assembled into mechanically stable CPS compartments. The CPS compartments were able to accommodate and release protein molecules but not lipids or nucleic acids. Intriguingly, we found that the CPS compartment size responds to osmotic stress and this compartment improves cell survival under high osmotic pressures, which was similar to the vacuole functionalities. By fine-tuning the synthesis and degradation of CPS with osmotic stressresponsive promoters, we achieved dynamic regulation of the size of CPS compartments and the host cells in response to external osmotic stress. Our results shed new light on developing prokaryotic artificial organelles with carbohydrate macromolecules.

Designing Intracellular Compartments for Efficient Engineered Microbial Cell Factories

“…131−134 Recently, capsular polysaccharide have been designed to assemble in vivo and form compartments that can exchange proteins and water molecules. 135 There are also many prokaryotic organelles, such as gas vesicles, that have been artificially constructed in engineered strains such as Halobacterium salinarum, 136 Escherichia coli, 137 and Saccharomyces cerevisiae. 138 Many synthetic scaffolds, such as nucleic acid interaction partners and protein interaction partners, have been developed to shorten the distance between enzymes by forming substrate delivery microcompartments and act as a controllable tool for constructing ASCs to promote the synthesis of target products.…”

“…In addition to the design of ASCs based on LLPS and cage-like encapsulation protein structures (such as BMC protein shells, encapsulins, VLPs), ferritin, polymeric vesicles, heat shock proteins, and liposomes have also been used to assemble various enzymes as microreactors and are not limited to being used in their original form. − Recently, capsular polysaccharide have been designed to assemble in vivo and form compartments that can exchange proteins and water molecules . There are also many prokaryotic organelles, such as gas vesicles, that have been artificially constructed in engineered strains such as Halobacterium salinarum , Escherichia coli, and Saccharomyces cerevisiae .…”