Erschienen in:
Molecular Microbiology, 81 (2011) 1, Seite 56-68
Sprache:
Englisch
DOI:
10.1111/j.1365-2958.2011.07669.x
ISSN:
0950-382X;
1365-2958
Entstehung:
Anmerkungen:
Beschreibung:
SummaryGas vesicles are gas‐filled protein structures increasing the buoyancy of cells. The gas vesicle envelope is mainly constituted by the 8 kDa protein GvpA forming a wall with a water excluding inner surface. A structure of GvpA is not available; recent solid‐state NMR results suggest a coil‐α‐β‐β‐α‐coil fold. We obtained a first structural model of GvpA by high‐performance de novo modelling. Attenuated total reflection (ATR)‐Fourier transform infrared spectroscopy (FTIR) supported this structure. A dimer of GvpA was derived that could explain the formation of the protein monolayer in the gas vesicle wall. The hydrophobic inner surface is mainly constituted by anti‐parallel β‐strands. The proposed structure allows the pinpointing of contact sites that were mutated and tested for the ability to form gas vesicles in haloarchaea. Mutations in α‐helix I and α‐helix II, but also in the β‐turn affected the gas vesicle formation, whereas other alterations had no effect. All mutants supported the structural features deduced from the model. The proposed GvpA dimers allow the formation of a monolayer protein wall, also consistent with protease treatments of isolated gas vesicles.