The accessory gas vesicle protein GvpM of haloarchaea and its interaction partners during gas vesicle formation

Abstract

Gas vesicles consist predominantly of the hydrophobic GvpA and GvpC, and the accessory proteins GvpF through GvpM are required in minor amounts during formation. GvpM and its putative interaction partners were investigated. GvpM interacted with GvpH, GvpJ and GvpL, but not with GvpG. Interactions were also observed in vivo in Haloferax volcanii transformants using Gvp fusions to the green fluorescent protein smGFP. Cells producing the hydrophobic M(GF)P contained a single fluorescent aggregate per cell, whereas cells containing L(GFP) or H(GFP) were fully fluorescent. The soluble L(GFP) formed stable co-aggregates with GvpM in L(GFP)M transformants, but the presence of GvpH resulted in the absence of M(GF)P foci in HM(GFP) transformants. Substitution- and deletion mutants of GvpM determined functionally important amino acids (aa). Substitution of a polar by a non-polar aa in the N-terminal region of GvpM had no effect, whereas a substitution of a non-polar by a polar aa in this region inhibited gas vesicle formation in transformants. Substitutions in region 44-48 of GvpM strongly reduced the number of gas vesicles, and deletions at the N-terminus resulted in Vac(-) transformants. Gas vesicle morphology was not affected by any mutation, implying that GvpM is required during initial stages of gas vesicle assembly.

Molecular genetic and physical analysis of gas vesicles in buoyant enterobacteria

“…In summary, although the production of gas vesicles was originally described in 1895, the specific role of each protein required for gas vesicle formation is still being dissected (DasSarma et al ., ; Offner et al ., ; Mlouka et al ., ; Pfeifer, ; Tavlaridou et al ., 2013; 2014; Xu et al ., ). This work describes the minimal gene set required for gas vesicles in and demonstrates that gas vesicles formed in E. coli and are physically indistinguishable.…”

Tree of motility – A proposed history of motility systems in the tree of life

“…These bacteria can spread on a solid medium by the spreading force in cell division under the control of surface tension through secreting substances that act as surfactants around the cells (Henrichsen, 1972;Kearns, 2010). Another example is the gas vesicles formed in cells by microorganisms present in the hydrosphere such as the phylum Cyanobacteria and Haloarchaea, which move up and down in the environment using the gas vesicles akin to a fish bladder ( Figure 1; type ii) (Tashiro, Monson, Ramsay, & Salmond, 2016;Tavlaridou, Winter, & Pfeifer, 2014). "Motility" which does not link directly with energy consumption is known in many higher plants, which have hard cell walls and are difficult to move.…”

Microbial gas vesicles as nanotechnology tools: exploiting intracellular organelles for translational utility in biotechnology, medicine and the environment

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