Protein ubiquitination and plant development

The highly conserved, well regulated ubiquitination pathway is an integral part of numerous cellular processes and is required for proper growth and development of eukaryotic organisms. The pathway effectively targets protein for degradation by the 26S proteasome and is also involved in protein activation, sorting and internalization. At the center of the ubiquitin conjugation cascade is the substrate binding E3 ubiqutin-ligase enzyme, which governs specificity of the pathway. Over 5% Arabidopsis genome is dedicated to protein ubiquitination/proteasomal degradation, the majority these genes encode for E3 ligases. A growing number of E3s have been implicated in diverse plant growth and developmental processes including photomorphogenesis, self-incompatibility and hormone signaling. However, the majority of E3s remain largely uncharacterized. The proposed research focuses on understanding the role of protein ubiquitination in plant development with particular interest paid to the function of the large and diverse family of RING (Really Interesting New Gene)- type E3 ligases. Of the 469 RING E3 encoding genes identified in the Arabidopsis genome only a handful has assigned biological functions. The objectives of this proposal include the functional characterization and identification of substrate proteins for sub-groups of RING E3 ligases. This research will identify novel roles for protein ubiquitination in plant development and make significant contributions to this area of research. Knowledge acquired from this work has potential implications in other areas of biological research, plant biotechnology and agriculture.