Elucidation of the molecular function of plasma membrane-localized OTU deubiquitylases in Arabidopsis thaliana

• Applicant: Professorin Dr. Erika Isono
• Subject Area: Plant Cell and Developmental Biology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441867841

Ubiquitylation is a posttranslational modification that is important for most biological processes in eukaryotic organisms. Among others, ubiquitylation often serves as a signal for protein degradation through the proteasomal, endocytic, or autophagosomal pathway. While ubiquitylating enzymes are the primary determinant of the stability of a given protein during these processes, deubiquitylating enzymes (DUBs) can also regulate the degradation of a protein by removing ubiquitin and rescuing the protein from degradation. DUBs are regulated at various levels including regulations at the transcriptional level as well as the localization, posttranslational modification, and the enzymatic activity. We have identified two DUBs in Arabidopsis, OTU11 and OTU12, as plasma membrane-localized DUBs. Both enzymes have very low activity as recombinant proteins but can be activated by binding to anionic lipids and are involved in the regulation of plasma membrane proteins. We now found that OTU11 and OTU12 re-localize to cytosolic foci under different stress conditions, however, the molecular basis for this re-localization and the physiological functions of DUBs in cellular stress responses is not yet understood. The goal of this project proposal is thus to (1) identify the nature of compartments containing OTU11 and OTU12 upon stress and (2) to identify and characterize the interactors and possible targets of these DUBs. We will apply biochemical, cell biological, and genetic methods and expect that the outcome of this project will contribute to gain deeper insights into the function of DUBs in the regulation of cellular stress response.

• DFG Programme: Research Grants