H2O2 signalling from mitochondria and chloroplast to the nucleus in the green microalga Chlamydomonas: in vivo and in vitro approaches

Reactive oxygen species (ROS) are mainly produced in the mitochondrial (Larosa and Remacle, 2018) and in the photosynthetic electron transport chains (Pospíšil, 2009). Historically, ROS were only considered as toxic molecules for cells, leading to oxidation of proteins, lipids and DNA.
Nowadays, the ROS-molecule H2O2 is increasingly being recognized as a signaling molecule due to the fact that it is relatively stable compared to the other ROS-molecules and H2O2 can potentially travel across membranes (Mittler, 2017). H2O2 signals via rapid reactions with protein cysteine sulfurs, which results in an altered protein structure and function (Pedre et al., 2018). Such cysteine modifications are known as S-sulfenylations (-SOH).
So far, hundreds of sulfenylated proteins have been identified in the model plant Arabidopsis thaliana (Waszczak et al., 2014; Akter et al., 2015). In this project we want to (i) identify C. reinhardtii crucial redox enzymes which effect the phenotype under H2O2-stress inducing conditions; (ii) trap and identify sulfenylated proteins involved in the redox signaling, using dimedone-based carbon nucleophiles and mass spectrometry; (iii) in vitro characterize the oxidation kinetics and the oxidation induced structural changes on one of the identified redox-sensing proteins.

This work is supported by the Fonds Wetenschappelijk Onderzoek – Vlaanderen (FWO) and the Fonds de la Recherche Scientifique – FNRS under EOS Project No. 30829584.

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