PROSITE documentation PDOC00207

Gas vesicles protein GVPa signatures

Gas vesicles are small, hollow, gas filled protein structures found in several cyanobacterial and archaebacterial microorganisms [1]. They allow the positioning of the bacteria at the favorable depth for growth. Gas vesicles are hollow cylindrical tubes, closed by a hollow, conical cap at each end. Both the conical end caps and central cylinder are made up of 4-5 nm wide ribs that run at right angles to the long axis of the structure. Gas vesicles seem to be constituted of two different protein components: GVPa and GVPc.

GVPa, a small protein of about 70 amino acid residues, is the main constituent of gas vesicles and form the essential core of the structure. The sequence of GVPa is extremely well conserved.

GvpJ and gvpM, two proteins encoded in the cluster of genes required for gas vesicle synthesis in the archaebacteria Halobacterium halobium and Haloferax mediterranei, have been found [2] to be evolutionary related to GVPa. The exact function of these two proteins is not known, although they could be important for determining the shape determination gas vesicles.

The N-terminal domain of Aphanizomenon flos-aquae protein gvpA/J is also related to GVPa.

We developed two signature patterns for this family of proteins. The first pattern is located in the N-terminal section while the second is in the C-terminal section.