GvpA

GvpA is a gas vesicle structural protein found in different phyla of bacteria and archaea for example in Halobacterium salinarum or Haloferax mediterranei. 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 a favourable depth for growth.

gvpA gas vesicle synthesis protein GvpA
Identifiers
OrganismHalobacterium salinarum
NRC-1
SymbolgvpA
Entrez1446785
RefSeq (Prot)NP_045970.1
UniProtP08958
Other data
ChromosomeGenome: 0.02 - 0.02 Mb
GvpA
Identifiers
SymbolGvpA
PfamPF00741
InterProIPR000638
PROSITEPDOC00207

GvpA associates with GvpC, to build up gas vesicles, hollow protein structures which are used by planktonic organisms to perform vertical migration. GvpA makes up most of the structure, as so called "ribs", rigid β-sheets, whereas GvpC stabilizes the vesicle against collapse by crosslinking as α-helices.[2][3][4]

Sequence

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 salinarium and Halobacterium mediterranei (Haloferax mediterranei), have been found [5] to be evolutionarily 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.

Structure

GvpA of Halobacterium salinarum is a 76 amino acid long 8 kDa hydrophobic monomer.[3]

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.

References
  1. Walsby AE, Hayes PK (December 1989). "Gas vesicle proteins". Biochem. J. 264 (2): 313–22. doi:10.1042/bj2640313. PMC 1133585. PMID 2513809.
  2. Englert C, Pfeifer F (May 1993). "Analysis of gas vesicle gene expression in Haloferax mediterranei reveals that GvpA and GvpC are both gas vesicle structural proteins". J. Biol. Chem. 268 (13): 9329–36. PMID 7683649.
  3. UniProt, UniProt GvpA from halobacterium salinarum.
  4. Walsby AE (March 1994). "Gas vesicles". Microbiol. Rev. 58 (1): 94–144. doi:10.1128/mmbr.58.1.94-144.1994. PMC 372955. PMID 8177173.
  5. Jones JG, Young DC, DasSarma S (June 1991). "Structure and organization of the gas vesicle gene cluster on the Halobacterium halobium plasmid pNRC100". Gene. 102 (1): 117–22. doi:10.1016/0378-1119(91)90549-Q. PMID 1864501.
This article incorporates text from the public domain Pfam and InterPro: IPR000638
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