Gas vesicle formation in halophilic Archaea

Abstract

Gas vesicles are intracellular, microbial flotation devices that consist of mainly one protein, GvpA. The formation of halobacterial gas vesicles occurs along a complex pathway involving 14 different gvp genes that are clustered in a genomic region termed the "vac region". Various vac regions found in Halobacterium salinarum (p-vac and c-vac), Haloferax mediterranei (mc-vac), and Natronobacterium vacuolatum (nv-vac) have been investigated. Except for the latter vac region, the arrangement of the gvp genes is identical. Single gvp genes have been mutated to study the effect on gas vesicle synthesis in transformants and to determine their possible function. Each vac region exhibits a characteristic transcription pattern, and regulatory steps have been observed at the DNA, RNA, and protein level, indicating a complex regulatory network acting during gas vesicle gene expression.

Eight of Fourteen gvp Genes Are Sufficient for Formation of Gas Vesicles in Halophilic Archaea

“…However, gvp gene function can still be determined by this method, especially when the respective control transformant indicates normal gas vesicle formation. The differences obtained with mutations in the gvpACNO gene cluster have already been discussed (29,35).…”

Overproduction of individual gas vesicle proteins perturbs flotation, antibiotic production and cell division in the enterobacterium Serratia sp. ATCC 39006

“…These hollow cylindrical structures are permeable only to dissolved gas in the medium, and thus, gas vesicles reduce the density of bacterial cells, allowing them to fully colonize a static water column through flotation (Walsby, 1994). Gas vesicles are sensitive to pressure and production is often regulated in response to environmental and nutritional inputs from the organism's surroundings (Hechler & Pfeifer, 2009;Pfeifer et al, 2002;Ramsay et al, 2011;Tashiro et al, 2016). To date, all gas vesicles identified are composed of the small hydrophobic protein GvpA, which self-assembles into a ribbed array structure forming the gas vesicle walls (Buchholz et al, 1993;Hayes et al, 1988;and reviewed extensively in Walsby, 1994).…”

Elucidation of the gas vesicle gene clusters in cyanobacteria of the genusArthrospira(Oscillatoriales, Cyanophyta) and correlation with ITS phylogeny

“…Gas vacuoles, whose function is to provide cells with buoyancy, are present in many different prokaryotes, including cyanobacteria and archaea, particularly in those inhabiting aquatic environments (Walsby, 1994;Pfeifer et al, 1997;DasSarma & Arora, 1997). These structures are made up of stacks of cylindrical gas vesicles, whose walls are composed solely of proteins.…”

“…In cyanobacteria up to eight other gas vesicle genes have been identified (Kinsman & Hayes, 1997;Albouy et al, 2001;Mlouka et al, 2004). In the case of halophilic archaea as many as 12 additional genes have been found (DasSarma & Arora, 1997;Pfeifer et al, 1997).…”