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A small molecule with a high sun protection factor

A team from Freiburg University showed how cyanobacteria adapt to changing light intensities

A small molecule with a high sun protection factor

Cyanobacteria in a photobioreactor at different light intensities

Cyanobacteria are photosynthetic organisms, which get their energy from sun light. During this process they are producing oxygen. Photosynthetic systems are sensitive to an excess of light. Scientists did not know much about the molecular mechanisms how cyanobacteria respond to fluctuations in light intensity. The idea was that the respective signalling and regulatory systems consist mainly of proteins. The groups around Prof. Annegret Wilde and Prof. Wolfgang Hess from the Institute of Biology III of Freiburg University demonstrated that nature has solved this problem using the RNA molecule PsrR1. This RNA consists of only 131 nt and thus, is much smaller than messenger RNAs (mRNA) coding for regulatory proteins and acts directly at RNA level. The regulatory RNA PsrR1 has a central function in the reorganization of the photosynthetic apparatus upon high-light stress. The results of the research have been published in the journal “The Plant Cell”.

Experiments of the members of the two labs showed that short RNA molecules are important regulators not only in eukaryotes but also in unicellular bacteria. PsrR1 is a so called regulatory RNA molecule. It controls which mRNAs are translated into protein. The regulatory RNA binds to different parts of mRNAs thereby altering the efficiency of translation and mRNA stability. This leads to a decreased synthesis of pigments and proteins of photosystem I. The Photosystem I is part of the photosynthetic machinery in cyanobacteria and plants which converts the light energy of the sun into chemical energy. Decreasing light absorption thus protects the photosynthetic apparatus from light stress.

Cyanobacteria live in every light environment on Earth: in rivers, lakes, in all climate zones, in deserts, but can grow also on buildings and in deserts and exist in aquariums. They populated our Earth already more than 3 billion years ago and enriched the atmosphere with oxygen, a byproduct of their metabolism. In the oceans, which cover 71 percent of Earth`s surface, oxygen evolving cyanobacteria are the biggest group of photosynthetic organisms. Thus, cyanobacteria constitute a major component of the biosphere. The new findings will help to establish these organisms for biotechnological applications. Cyanobacteria have a great potential as producers of biofuels, food supplements, pharmaceutical and cosmetic products.


Original publication
J. Georg, D. Dienst, N. Schürgers, T. Wallner, D. Kopp, D. Stazic, E. Kuchmina, S. Klähn, H. Lokstein, W.R. Hess, A. Wilde (2014): The Small Regulatory RNA SyR1/PsrR1 Controls Photosynthetic Functions in Cyanobacteria. Plant Cell. 2014 Sep 23. pii: tpc.114.129767. [Epub ahead of print] PubMed PMID: 25248550.

Prof. Dr. Annegret Wilde
Institute for Biology III
University of Freiburg
Tel.: +49 (0)761 203 97828
e-mail: annegret.wilde@biologie.uni-freiburg.de

Prof. Dr. Wolfgang Hess
Institute for Biology III
University of Freiburg
Tel.: +49 (0)761 203 2796
e-mail: wolfgang.hess@biologie.uni-freiburg.de


 Click here for a printable version (pdf) of the press release.


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