Vibrio regulatory RNA of OmpA
Encyclopedia
VrrA is a non-coding RNA
that is conserved across all Vibrio species of bacteria and acts as a repressor for the synthesis of the outer membrane protein OmpA
. This non-coding RNA was initially identified from Tn5 transposon
mutant libraries of Vibrio Cholerae and its location within the bacterial genome was mapped to the intergenic region between genes VC1741 and VC1743 by RACE analysis.
Outer membrane vesicles are secreted from the surface of gram negative bacteria where they are though to aid in virulence
. Little is known about how these vesicles aid virulence but it has been speculated that they may contribute by secreting toxins and help in the evasion of the immune system
. Recent studies showed that VrrA expression is activated by the alternative stress sigma factor
, sigma E, unlike other strains of bacteria such as E. coli
and Salmonella
it doesn’t require the Hfq protein to regulate the sigma factor. It was also shown that VrrA transcription
increases on exposure to UV light and that over expression of VrrA resulted in an increase in outer membrane vesicles secreted. From these studies it has been suggested that VrrA acts to relieve outer membrane stress by limiting the synthesis of OmpA protein and that outer membrane vesicles provide the bacteria physical protect against UV light.
Non-coding RNA
A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...
that is conserved across all Vibrio species of bacteria and acts as a repressor for the synthesis of the outer membrane protein OmpA
OmpA-like transmembrane domain
OmpA-like transmembrane domain is an evolutionarily conserved domain of outer membrane proteins. This domain consists of an eight-stranded beta barrel. OmpA is the predominant cell surface antigen in enterobacteria found in about 100,000 copies per cell. The expression of OmpA is tightly regulated...
. This non-coding RNA was initially identified from Tn5 transposon
Transposon
Transposable elements are sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell. The mechanism of transposition can be either "copy and paste" or "cut and paste". Transposition can create phenotypically significant mutations and alter the cell's...
mutant libraries of Vibrio Cholerae and its location within the bacterial genome was mapped to the intergenic region between genes VC1741 and VC1743 by RACE analysis.
Outer membrane vesicles are secreted from the surface of gram negative bacteria where they are though to aid in virulence
Virulence
Virulence is by MeSH definition the degree of pathogenicity within a group or species of parasites as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenicity of an organism - its ability to cause disease - is determined by its...
. Little is known about how these vesicles aid virulence but it has been speculated that they may contribute by secreting toxins and help in the evasion of the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
. Recent studies showed that VrrA expression is activated by the alternative stress sigma factor
Sigma factor
A sigma factor is a bacterial transcription initiation factor that enables specific binding of RNA polymerase to gene promoters. Different sigma factors are activated in response to different environmental conditions...
, sigma E, unlike other strains of bacteria such as E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
and Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
it doesn’t require the Hfq protein to regulate the sigma factor. It was also shown that VrrA transcription
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
increases on exposure to UV light and that over expression of VrrA resulted in an increase in outer membrane vesicles secreted. From these studies it has been suggested that VrrA acts to relieve outer membrane stress by limiting the synthesis of OmpA protein and that outer membrane vesicles provide the bacteria physical protect against UV light.