The PrrF RNAs are small
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 ...
s involved in iron homeostasis and are encoded by all ''
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...
'' species. The PrrF RNAs are
analogs of the
RyhB RNA, which is encoded by enteric bacteria. Expression of the PrrF RNAs is repressed by the ferric uptake regulator (Fur) when cells are grown in iron-replete conditions. Under iron limitation, the PrrF RNAs are expressed and act to negatively regulate several genes encoding iron-containing proteins, including SodB and succinate dehydrogenase. As such, PrrF regulation "spares" iron when this nutrient becomes scarce.
PrrF and virulence
In ''
Pseudomonas aeruginosa
''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...
'', the PrrF RNAs are required for the production of the Pseudomonas quinolone signal (PQS), a quorum sensing molecule that activates the expression of several virulence genes. The phenomenon is mediated by PrrF repressing the expression of enzymes that degrade
anthranilic acid
Anthranilic acid is an aromatic acid with the formula C6H4(NH2)(CO2H) and has a sweetish taste. The molecule consists of a benzene ring, ''ortho''-substituted with a carboxylic acid and an amine. As a result of containing both acidic and basic f ...
, which is the precursor for PQS synthesis. Due to this regulatory link with PQS, the PrrF RNAs are predicted to play a role in pathogenesis.
The PrrF RNAs of ''P. aeruginosa'' are unique from other ''
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...
'' species, in that they are encoded by two highly homologous genes, ''prrF1'' and ''prrF2'', which are located in tandem on the chromosome. The tandem arrangement of the ''prrF'' genes allows for the expression of a third, heme-regulated non-coding RNA named PrrH, which regulates genes involved in heme homeostasis. Heme is an abundant source of iron in the human host, and ''P. aeruginosa'' is the only ''
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...
'' species capable of causing infection in humans. Therefore, it is hypothesized that the PrrH RNA plays a role in ''P. aeruginosa's'' adaptability as a human pathogen.
Both homologues inhibit translation of ''antR'' mRNA, which affects quorum sensing and virulence factor production.
See also
*
HrrF RNA
*
NrrF RNA
*
Aggregatibacter iron-regulated sRNA
References
External links
*
Non-coding RNA
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