Iron stress repressed RNA
Encyclopedia
Iron stress repressed RNA (IsrR) is a cis-encoded antisense RNA which regulates the expression of the photosynthetic protein isiA. IsiA expression is activated by the Ferric uptake regulator protein
(Fur) under iron
stress conditions. IsiA enhances photosynthesis by forming a ring around photosystem I
which acts as an additional antenna complex.
IsrR is abundant when there is a sufficient iron concentration. IsrR is encoded for within the opposite stand of isiA gene and contains a conserved stem loop secondary structure. Under sufficient iron conditions IsrR binds to its complementary region which corresponds to the central third of the isiA mRNA. The resulting duplex RNA is then targeted for degradation. This allows the antisense RNA to act as a reversible switch that responds to changes in environmental conditions to modulate the expression of the isiA protein.
IsrR was originally identified within cyanobacteria but may be conserved throughout a number of photosynthetic species from multiple kingdoms. At present IsrR is the only non coding RNA identified that has a regulatory role on photosynthetic proteins.
Ferric uptake regulator family
In molecular biology, the ferric uptake regulator family of proteins includes metal ion uptake regulator proteins. These are responsible for controlling the intracellular concentration of iron in many bacteria. Although iron is essential for most organisms, high concentrations can be toxic because...
(Fur) under iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
stress conditions. IsiA enhances photosynthesis by forming a ring around photosystem I
Photosystem I
Photosystem I is the second photosystem in the photosynthetic light reactions of algae, plants, and some bacteria. Photosystem I is so named because it was discovered before photosystem II. Aspects of PS I were discovered in the 1950s, but the significances of these discoveries was not yet known...
which acts as an additional antenna complex.
IsrR is abundant when there is a sufficient iron concentration. IsrR is encoded for within the opposite stand of isiA gene and contains a conserved stem loop secondary structure. Under sufficient iron conditions IsrR binds to its complementary region which corresponds to the central third of the isiA mRNA. The resulting duplex RNA is then targeted for degradation. This allows the antisense RNA to act as a reversible switch that responds to changes in environmental conditions to modulate the expression of the isiA protein.
IsrR was originally identified within cyanobacteria but may be conserved throughout a number of photosynthetic species from multiple kingdoms. At present IsrR is the only non coding RNA identified that has a regulatory role on photosynthetic proteins.