NIH Postdoctoral Fellow Rice University Rosharon, Texas
The Ubiquitin Proteasome System (UPS) is integral to eukaryotic cell function, facilitating a range of processes including transcriptional activation, protein quality control, DNA damage repair, cell cycle progression and cell death. The UPS involves ubiquitination, the attachment of multiple ubiquitin molecules to selected substates, followed by degradation of the modified proteins by the multi-proteolytic 26S Proteasome. Targeting proteins for ubiquitin dependent degradation is achieved via a cascade that utilizes a large and diverse family of substrate-recruiting ubiquitin ligase (E3) enzymes. For Arabidopsis, most E3s are involved in modulating cellular processes and signaling pathways to facilitate the appropriate responses to stress. In fact, different stressors engage common E3s to regulate cellular responses. 80% of Arabidopsis genes encoding for Really Interesting New Gene (RING)-type E3s are differentially expressed in response to biotic or abiotic stresses, and 42% are responsive to both types of stresses. The role of specific RING-type E3s in facilitating responses to multiple abiotic stresses, such as nutrient and water deprivation, will be discussed. As well as a RING-type E3 that regulate both biotic and abiotic stress responses via the ubiquitin dependent degradation of a single substrate.