Identifying RING-type E3s involved in nutrient stress responses in Arabidopsis thaliana

Abstract

The Ubiquitin Proteasome System (UPS) is a eukaryotic protein degradation system that regulates nutrient uptake and translocation through mediating the degradation of enzymes, transporters, signalling proteins, transcription regulators, etc. Ubiquitin ligases (E3s) are central to the UPS as they govern specificity of substrate selection, interacting with the substrate directly and mediating ubiquitination. In this thesis I examine eight RING-type E3s in facilitating responses to nitrogen, phosphorus, and iron stress in Arabidopsis thaliana. Three E3s were investigated further: ATL12, ARI12, and WAVH1. ATL12 and ARI12 were determined to be involved in the response to iron stress, with results suggesting ATL12 is required for proper regulation of the iron deficiency response (IDR) when iron levels are low, and that ARI12 is involved in attenuating the IDR when levels are sufficient/high. Additionally, results suggest that WAVH1 promotes lateral root emergence and is required for proper primary root growth and gravitropism under nitrogen limitation.