Dissection of sulfurtransferase-mediated persulfidation in plant mitochondria

• Applicant: Dr. Anna Moseler
• Subject Area: Plant Biochemistry and Biophysics ; Plant Physiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 539230919

An ever-growing body of evidence suggests that hydrogen sulfide (H2S) plays a role in cellular signalling similar to the role of other gaseous molecules such as nitric oxide (NO). H2S signalling occurs through persulfidation of critical cysteine residues and cysteine persulfides have been found in free cysteine, small peptides like glutathione, as well as in proteins. In proteins, persulfidation has gained attention as a reversible posttranslational modification that contributes to protein regulation or protection. H2S signalling has been associated with various plant processes ranging from abiotic and biotic stress response to development to stomatal movement. Exogenous application of H2S has been reported to have positive effects on plant germination and yield, highlighting a potential relevance for crop production. Despite this increasingly recognised importance, central questions surrounding protein persulfidation remain unanswered. We, for instance, do not know how H2S is endogenously produced and if downstream persulfidation occurs non-enzymatically via H2S or enzymatically through corresponding persulfidases. An enzyme that has been implicated in the persulfidation of proteins or low molecular weight molecules is the 3-mercaptopyruvate sulfurtransferase (MST). The overarching goal of this project is to understand how MSTs contribute to persulfide generation in Arabidopsis mitochondria by applying a combination of genetic, physiological and biochemical approaches. We will functionally characterize the pathway leading to persulfide formation that supposedly starts with the transamination of cysteine to form 3-mercaptopyruvate. 3-mercaptopyruvate is then used by 3‐mercaptopyruvate sulfurtransferase 1 (MST1), which we think is a key player in either H2S production or direct persulfidation of molecules. To dissect that, the first aim is to identify and characterize the cysteine transaminase. The second aim is to investigate whether the function of MST1 is dedicated to H2S production or whether is rather involved in direct persulfidation of molecules. For this, we will determine the amounts of sulfide and sulfane sulfur as well as persulfidated proteins. Furthermore, we will analyse whether disturbance of mitochondrial sulfide homeostasis related to the suggested MST function will cause any pronounced phenotype. In summary, this work will set a framework for understanding the potential roles of MST-mediated persulfidation and will help mapping sulfur transfer events across interconnected pathways.

• DFG Programme: Research Grants