The PrrF RNAs are small
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not 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 important types of non-c ...
s involved in iron homeostasis and are encoded by all ''
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...
'' species. The PrrF RNAs are
analogs of the
RyhB RNA
RyhB RNA is a 90 nucleotide RNA that down-regulates a set of iron-storage and iron-using proteins when iron is limiting; it is itself negatively regulated by the ferric uptake repressor protein, Fur ( Ferric uptake regulator).
Discovery
The gene ...
, 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 encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerugi ...
'', 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, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...
'' 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, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...
'' 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
HrrF RNA (''Haemophilus'' regulatory RNA responsive to iron Fe) is a small non-coding RNA involved in iron homeostasis in ''Haemophilus'' species. Orthologues exist only among other '' Pasteurellacae.'' Iron- regulated sRNAs JA01- JA04 were ident ...
*
NrrF RNA
NrrF is a non-coding RNA which is regulated by the Ferric uptake regulator (Fur) protein in bacteria. This non-coding RNA was identified in ''Neisseria meningitidis'' and is involved in iron regulation of the succinate dehydrogenase genes sdhA an ...
*
Aggregatibacter iron-regulated sRNA Four non-coding small RNAs containing a Fur box-like (Ferric uptake regulator family, ferric uptake regulator) sequence were identified by bioinformatics analysis in ''Aggregatibacter actinomycetemcomitans'' ''HK1651'' called JA01-JA04. The transcri ...
References
External links
*
Non-coding RNA
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