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E-GEOD-63328 - The sRNA SorY confers resistance during photooxidative stress by affecting a metabolite transporter in Rhodobacter sphaeroides
Released on 18 November 2014, last updated on 28 November 2014
Rhodobacter sphaeroides 2.4.1
Exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen (1O2) in the facultative photosynthetic bacterium Rhodobacter sphaeroides. We have identified SorY as an sRNA, which is induced under several stress conditions and confers increased resistance against 1O2. SorY by direct interaction decreases the levels of takP mRNA, encoding a TRAP-T transporter. A takP mutant shows higher resistance to 1O2 than the wild type, which is no longer affected by SorY. We present a model in which SorY reduces the metabolite flux into the TCA cycle by reducing malate import through TakP. It was previously shown that oxidative stress in bacteria leads to switch from glycolysis to the pentose phosphate cycle and to reduced activity of the tricaboxylic acid cycle. As a consequence the production of the prooxidant NADH is reduced and production of the protective NADPH is enhanced. In R. sphaeroides enzymes for glycolysis, pentose phosphate pathway, Entner–Doudoroff pathway and gluconeogenesis are induced in response to 1O2 by the alternative sigma factor RpoHII. The same is true for the sRNA SorY. By limiting malate import SorY thus contributes to the balance of the metabolic fluxes under photooxidative stress conditions. This assigns a so far unknown function to an sRNA in oxidative stress response. RNA samples collected from a control strain harbouring an empty vector (2.4.1pBBR) and of the SorY overexpressing strain (2.4.1pBBRSorYi) after 10 min of 1O2 stress were analyzed by two-color microarrays
transcription profiling by array
Gabriele Klug <Gabriele.Klug@mikro.bio.uni-giessen.de>, Gabriele Klug, Lennart Weber