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Structural characteristics of halobacterial gas vesicles
Sonja Offner1, Ulrike Ziese2, Gerhard Wanner3
1Institut für Mikrobiologie und Genetik, Technische Universität Darmstadt, Schnittspahnstr. 10, D-64287 Darmstadt, Germany.
Microbiology (Reading, England)
|June 5, 1998
Summary
Gas vesicle shape in halophilic archaea is determined by multiple gene products, not just the GvpA protein. This finding reveals a complex regulatory mechanism for gas vesicle biogenesis.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Gas vesicle formation in halophilic archaea is controlled by a conserved DNA region (vac region) encoding 14 genes.
- Different archaeal species exhibit distinct gas vesicle morphologies (spindle-shaped vs. cylindrical).
Purpose of the Study:
- To investigate the genetic determinants of gas vesicle shape in halophilic archaea.
- To elucidate the roles of specific gvp genes in gas vesicle biogenesis and morphology.
Main Methods:
- Homologous and heterologous complementation of gvp gene clusters in Halobacterium salinarum and Haloferax mediterranei.
- Transmission electron microscopy (TEM) of wild-type and chimeric gas vesicles.
- Analysis of moiré patterns in frozen hydrated gas vesicles.
Main Results:
- Complementation experiments confirmed the dependence of the c-gvpA promoter on products from the c-gvpE-M region.
- Chimeric gas vesicles could be formed, indicating that GvpA alone does not exclusively determine shape.
- TEM analysis revealed a helical structure of the gas vesicle ribs, not a stack of hoops.
Conclusions:
- Gas vesicle shape is likely determined by a dynamic interplay of multiple gvp gene products.
- The structural organization of gas vesicle ribs involves a low-pitch helix.