Gas Vesicle Nanoparticles

Gas vesicles are intracellular nanoparticles produced by many prokaryotic microorganisms. These buoyant, gas-filled and phase-bright organelles promote movement of cells vertically in the water column. Easily isolated by flotation after cell disruption, the nanoparticles are surrounded by a lipid-free protein membrane that is extremely stable and gas permeable. Gas vesicle biogenesis begins with small bicones and proceeds to longer spindle or cylindrical-shaped structures, with the size and shape dependent on the species. Water is excluded from the gas vesicle interior as a consequence of hydrophobicity of the inner surface of the membrane. Two major and five minor gas vesicle proteins coded by large gvp ( g as v esicle p rotein) gene clusters with a dozen or more genes have been found in many species. Such gene clusters are necessary and sufficient for biogenesis. Research on gas vesicle architecture is ongoing, and gas vesicle nanoparticles are being engineered for uses in environmental and biomedical applications. Diverse prokaryotes make organelles known as gas vesicles (GVs) for buoyancy. Gas vesicles are common in cyanobacteria, halophilic Archaea and other aquatic microorganisms. Toxic blooms are made by some gas vesicle-containing cyanobacteria. Buoyancy increases the availability of light and oxygen to cells for photosynthesis and respiration. Gas vesicle synthesis requires a cluster of about a dozen genes. Gas vesicles are easily purified and harvested as nanoparticles (GVNPs). GVNPs are extremely stable and may be genetically engineered to display foreign proteins. The GVNPs are being developed for biomedical and environmental applications.