Riboregulation of photosynthesis genes in the adaptation to different growth conditions in Rhodobacter sphaeroides
Final Report Abstract
Most bacteria have to steadily adapt to changes in their environment. The aquatic bacterium Rhodobacter sphaeroides uses oxygen for aerobic respiration. When no oxygen is present (e.g. in certain zones of a lake) it can form pigment-protein complexes and perform anoxygenic photosynthesis when light is present. This process needs to be well controlled. The simultaneous presence of pigments, light and oxygen would not only waste energy but would cause the generation of the highly reactive and harmful singlet oxygen. For a long time, it was anticipated that such processes are mostly controlled at level of transcription: the production of mRNA from the DNA of a gene. Now it is well known that also the degradation of mRNA plays an important role in regulation of gene expression. RNA degradation is catalyzed by ribonucleases (RNases) and also controlled by other RNA-binding proteins and small non-coding RNAs (sRNAs) that can base pair to the mRNAs. We performed transcriptome analyses (determination of levels of all cellular RNAs) for the wild type and a number of mutants of R. sphaeroides during microaerobic (low oxygen, no light) and phototrophic (no oxygen, light) growth, both in exponential phase when nutrients are available and bacteria are dividing with maximal rate, and in stationary phase, when nutrients are limited and bacterial cultures stop growing. In natural environments bacteria are mostly in stationary phase, while experiments in the lab are mostly performed in exponential phase. The data revealed important roles of RNAse E and RNase III (both endoribonucleases) and limited influence of PNPase (polynucleotide phosphorylase, exoribonuclease) on the regulated formation of photosynthetic complexes and gives some insights into the underlying mechanisms. Also, the sRNA StsR and the small RNA-binding protein CcaF1 contribute to this regulation. Importantly, growth phase has a strong impact on the change of gene expression between microaerobic and phototrophic growth.
Publications
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A Complex Network of Sigma Factors and sRNA StsR Regulates Stress Responses in R. sphaeroides. International Journal of Molecular Sciences, 22(14), 7557.
Eisenhardt, Katrin M. H.; Remes, Bernhardt; Grützner, Julian; Spanka, Daniel-Timon; Jäger, Andreas & Klug, Gabriele
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Antisense RNA asPcrL regulates expression of photosynthesis genes in Rhodobacter sphaeroides by promoting RNase III-dependent turn-over of puf mRNA. RNA Biology, 18(10), 1445-1457.
Reuscher, Carina M. & Klug, Gabriele
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Impact of PNPase on the transcriptome of Rhodobacter sphaeroides and its cooperation with RNase III and RNase E. BMC Genomics, 22(1).
Spanka, Daniel-Timon; Reuscher, Carina Maria & Klug, Gabriele
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Ribonuclease E strongly impacts bacterial adaptation to different growth conditions. RNA Biology, 20(1), 120-135.
Börner, Janek; Friedrich, Tobias; Bartkuhn, Marek & Klug, Gabriele
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RNase III participates in control of quorum sensing, pigmentation and oxidative stress resistance in Rhodobacter sphaeroides. Molecular Microbiology, 120(6), 874-892.
Börner, Janek; Friedrich, Tobias & Klug, Gabriele
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The Small RNA-Binding Protein CcaF1 Promotes Formation of Photosynthetic Complexes in Rhodobacter sphaeroides. International Journal of Molecular Sciences, 24(11), 9515.
Grützner, Julian; Börner, Janek; Jäger, Andreas & Klug, Gabriele
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The Impact of the Major Endoribonucleases RNase E and RNase III and of the sRNA StsR on Photosynthesis Gene Expression in Rhodobacter sphaeroides Is Growth-Phase-Dependent. International Journal of Molecular Sciences, 25(16), 9123.
Börner, Janek; Grützner, Julian; Gerken, Florian & Klug, Gabriele
