OmpA-like transmembrane domain is an evolutionarily conserved
domain of
bacterial outer membrane
The bacterial outer membrane is found in gram-negative bacteria. Its composition is distinct from that of the inner cytoplasmic cell membrane - among other things, the outer leaflet of the outer membrane of many gram-negative bacteria includes ...
proteins. This domain consists of an eight-stranded
beta barrel
In protein structures, a beta barrel is a beta sheet composed of tandem repeats that twists and coils to form a closed toroidal structure in which the first strand is bonded to the last strand (hydrogen bond). Beta-strands in many beta-barrels are ...
.
OmpA is the predominant cell surface
antigen
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune respons ...
in enterobacteria found in about 100,000 copies per cell.
The expression of OmpA is tightly regulated by a variety of mechanisms. One mechanism by which OmpA expression is regulated in
Vibrio
''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive ...
species is by an antisense
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally im ...
called
VrrA.
Structure
The structure consists of an eight-stranded
Up-And-Down Beta-Barrel. The strands are connected by four extracellular loops and three intracellular turns.
Function
Numerous OmpA-like membrane-spanning domains contribute to bacterial virulence by a variety of mechanisms such as binding to host cells or immune regulators such as
Factor H
Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large (155 kilodaltons), soluble glycoprotein that circulates in human plasma (at typical concentrations of 200–300 micrograms ...
. Notable examples include ''E. coli'' OmpA and ''
Yersinia pestis
''Yersinia pestis'' (''Y. pestis''; formerly '' Pasteurella pestis'') is a gram-negative, non-motile, coccobacillus bacterium without spores that is related to both ''Yersinia pseudotuberculosis'' and ''Yersinia enterocolitica''. It is a facult ...
'' Ail. Several of these proteins are vaccine candidates.
''E. coli'' OmpA was shown to make specific interactions with the human
glycoprotein Ecgp on brain microvascular endothelial cells. ''
Cronobacter''
''sakazakii'' is a food borne pathogen causing meningitis in neonates and was shown to bind
fibronectin
Fibronectin is a high- molecular weight (~500-~600 kDa) glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. Fibronectin also binds to other extracellular matrix proteins such as collage ...
via OmpA and this played a significant role in invasion of the blood brain barrier. The ''Y. pestis'' protein Ail binds to laminin and heparin, therefore allowing bacterial attachment to host cells. The ''
Borrelia afzelii
''Borrelia afzelii'' is a species of '' Borrelia'' a bacterium that can infect various species of vertebrates and invertebrates.
Among 30 ''Borrelia'' known species, it is one of four which are likely to infect humans causing a variant of Lyme d ...
'' protein BAPKO_0422, is an OmpA-like transmembrane domain and binds to human
Factor H
Factor H is a member of the regulators of complement activation family and is a complement control protein. It is a large (155 kilodaltons), soluble glycoprotein that circulates in human plasma (at typical concentrations of 200–300 micrograms ...
.
See also
*
OmpA domain
References
Protein domains
Outer membrane proteins
{{membrane-protein-stub