From S-sulfenylation to S-sulfinylation: redox switches in plants

Adverse environmental conditions can trigger reactive oxygen species (ROS) production in plants. ROS can function as a "warning signal" to alarm the plant cell to initiate a protective response. In our research, we aim to understand how plant cells detect these warning signals and launch a “counter attack” against adverse conditions. One of the ways to sense ROS signal is via oxidative post-translational modifications (Oxi-PTMs) of cysteine residues (Cys) in proteins. These Oxi-PTMs can lead to an altered functional state of target proteins. My previous work focused on S-sulfenylation (SOH), which is reversible thanks to the existence of “redoxins” that are able to reduce it. Hence, SOH can exert a transient effect on protein function and are therefore termed ‘redox switches’. Another Cys Oxi-PTM, S-sulfinylation (SO2H), was considered to be irreversible and thought to keep the switch continuously “on” or “off”. However, SO2H on some sensor proteins was recently shown to be reversed by sulfiredoxin, a reducing enzyme. In this project, I hope to discover the sensor proteins that are amenable to reversion of SO2H and elucidate the specific redox switches mechanism in cellular signal transduction. The identified redox mechanisms could be extrapolated and contribute to optimize crops and vegetables to be more resilient against adverse environmental conditions.