Research Scientist CSIC
Instituto de Bioquímica Vegetal y Fotosíntesis
- Determine how cysteine homeostasis is regulated in the cytosol and the role of the cysteine-generated sulfide as a signaling molecule in senescence and autophagy.
- Determine the role it would play cyanide in signaling processes in which ethylene has traditionally been involved and decipher the mechanisms and potential targets of regulation by cyanide.
Hydrogen sulfide is already recognized as an important signaling molecule in mammalian systems, and emerging data suggest that H2S is a signaling molecule just as important as nitric oxide and oxygen peroxide in plants. Although sulfide is generated in chloroplasts and mitochondria, it is present predominantly in the charged HS– form due to the basic pH inside both organelles, thus requiring an active transporter, which is yet to be identified, to be released. In Arabidopsis, we found that the cytosolic L-cysteine desulfhydrase DES1 is involved in the degradation of cysteine, and therefore responsible for the generation of H2S in this cellular compartment. DES1 deficiency leads to the induction of autophagy. Moreover, we have demonstrated that sulfide in particular exerts a general effect on autophagy through negative regulation, in a way unrelated to nutrient deficiency. The mechanisms of H2S action and its molecular targets are largely unknown, although we have demonstrated that it is independent of the involvement of ROS. A molecular mechanism by which sulfide exerts its action involves the persulfidation of cysteines, consisting in the posttranslational modification of the thiol group (-SH) in target proteins to form a persulfide group (-SSH). Our group is studying whether persulfidation is the mechanism underlying the regulation of autophagy by sulfide.