OmpA-like transmembrane domain is an evolutionarily conserved
domain
A domain is a geographic area controlled by a single person or organization. Domain may also refer to:
Law and human geography
* Demesne, in English common law and other Medieval European contexts, lands directly managed by their holder rather ...
of
bacterial outer membrane
The bacterial outer membrane is found in gram-negative bacteria. Gram-negative bacteria form two lipid bilayers in their cell envelopes - an inner membrane (IM) that encapsulates the cytoplasm, and an outer membrane (OM) that encapsulates the p ...
proteins. This domain consists of an eight-stranded
beta barrel
In protein structures, a beta barrel (β barrel) is a beta sheet (β 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 ...
.
OmpA is the predominant cell surface
antigen
In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.
...
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, which have a characteristic curved-rod (comma) shape, several species of which can cause foodborne infection or soft-tissue infection called Vibriosis. Infection is commonly associated with eati ...
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 imp ...
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 (FH) 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 m ...
. Notable examples include ''E. coli'' OmpA and ''
Yersinia pestis
''Yersinia pestis'' (''Y. pestis''; formerly ''Pasteurella pestis'') is a Gram-negative bacteria, gram-negative, non-motile bacteria, non-motile, coccobacillus Bacteria, bacterium without Endospore, spores. It is related to pathogens ''Yer ...
'' Ail. Several of these proteins are vaccine candidates.
''E. coli'' OmpA was shown to make specific interactions with the human
glycoprotein
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...
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 col ...
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'' endemic to parts of Eurasia where it is one of the causative agents of Lyme disease. It is transmitted by hard-bodied ticks of the Ixodes genus (''Ixodes ricinus'' in Europe, and '' Ixodes persulc ...
'' protein BAPKO_0422, is an OmpA-like transmembrane domain and binds to human
Factor H
Factor H (FH) 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 m ...
.
See also
*
OmpA domain
References
Protein domains
Outer membrane proteins
{{membrane-protein-stub