Gas vesicles, also termed gas vacuoles, are nano compartments that assist in buoyancy in some prokaryotic species. Gas vesicles are largely protein composed; no lipids and carbohydrates are being reported.
Gas vacuoles found in prokaryotes are air-filled and are like cylindrical compartments. They assist in the buoyancy process.
Gas vacuoles are found in many marine bacteria, including cyanobacteria or blue-green algae, halophilic archaea, and green bacteria.
Gas Vacuole Structure
An accumulation of several gas vesicles is gas vacuoles. In different species, the form and distribution of gas vesicles vary. Gas vesicles are large and construct parallel bundles in cyanobacteria, while in purple sulfur bacteria, they are smaller and irregularly distributed.
Protein-bound structures are gas vacuoles. A protein-membrane covers each gas vesicle.
The vesicle's inner portion is hydrophobic, so it does not allow water to enter.
Gas vesicles have a diameter of about 75 nm and a length ranging from 200 to 1000 nm.
Regulation of Gas Vacuole Formation-
Proteins and extracellular environmental factors control gas vesicle synthesis.
Greater intensity of lights leads to inhibition of gas vesicle synthesis. In Anabaena, good light intensity collapses gas vesicles caused by the accumulation of higher turgor strain and photosynthetic products. Exposure to the high intensity of light on the ground may also affect the bacterial genome.
Gas vesicle synthesis is also controlled by the amount of oxygen. In halophilic archaea, oxygen deprivation prevents vesicle formation.
Carbohydrate accumulation reduces vesicle synthesis.
Increased environmental pH results in an increase in vesicle production in certain animals.
In aquatic species, gas vesicles typically occur as they are used to attenuate the buoyancy of the cell and adjust the location of the cell in the water column so that it can be optimally positioned for photosynthesis or transfer to places with somewhat oxygen.
Other aerobes which do not grow in a water column by using oxygen at the top are competing with species that might float out into the air-liquid interface.
In particular, by placing the organism in particular positions in a stratified water body to avoid osmotic shock, gas vesicles could be used to preserve maximum salinity. Large solute concentrations can cause osmosis to pull water out of the cell, leading to cell lysis.
In order to raise the formation of vesicles in Microcystis organisms, an increased extracellular pH supply is expected. GvpA and gvpC transcript levels increase during increased pH, leading to greater exposure to ribosomes for expression and contributing to upregulation of Gvp proteins. The higher transcription of these genes, the greater stability of mRNA or the reduced degradation of the synthesized transcripts can be attributed to it.
Gas vesicles tend to begin their life as tiny biconical structures (two cones linked along with the flat bases) that expand to the specific diameter then develop and extend their length. Exactly what regulates the diameter is unclear, but that might be a molecule that interferes with GvpA, but it may also alter the form of GvpA.
Two Gvp proteins control the formation of gas vesicles: GvpD, which prevents the expression from the proteins GvpA and GvpC, and the protein GvpE induces expression Vesicle formation is also influenced by extracellular environmental variables, either by regulating the development of Gvp protein or by directly disrupting the structure of the vesicle.
Role in Vaccine Development
The gvpC gaseous vesicle gene from Halobacterium sp. is majorly preferred as a delivery method for research on vaccines.
A number of protein properties encoded by the gvpC gas vesicle gene enable it to be seen as an antigen carrier and adjuvant. It is prone to microbial breakdown, stable, tolerates significantly higher temperatures (up to 50 °C) and is anti-pathogenic to humans.
To build subunit vaccines with immunologic responses which can last for a longer period of time, multiple antigens from different human pathogens have been consolidated into the gvpC gene.
The gvpC gene of Halobacteria is based on various genomic fragments coding for many proteins of the Chlamydia trachomatis pathogen, including OmcB, MOMP, and PompD. In vitro cell assessments demonstrate the expression of the Chlamydia genes on target cells by imagining strategies and demonstrate characteristic immunological responses including the activity of TLRs and the development of pro-inflammatory cytokines.
It is possible to use the gas vesicle gene as a delivery vehicle to produce a future Chlamydia vaccine. This method's drawbacks include the need to reduce the harm of the GvpC protein itself while integrating as many of the target genes of the vaccine into the section of the gvpC gene.