Principal investigator:

Üstün, Suayb,
Zentrum für Molekularbiologie der Pflanzen (ZMBP)

Abteilung Allgemeine Genetik

Auf der Morgenstelle 32

72076 Tübingen

Phone: 49 7071 29 73230

suayib.uestuenspam prevention@zmbp.uni-tuebingen.de

Summary:

Regulated protein turnover mediated by the ubiquitin proteasome system (UPS) is involved in many cellular processes, including immunity. Recent advances revealed that the proteasome is exploited by plant pathogenic bacteria, including the suppression of its activity by degrading proteasomes via autophagy. However, in addition to the requirement of the proteasome during plant defence responses, its proper function is also essential for bacterial pathogenicity. This implies that fine-tuning of the proteasome regulation is central to the outcome of plant-microbe interactions. This project aims to identify the specificity of proteasome regulation during plant immunity by using a combination of cell biological, transcriptomics and biochemical methods. Preliminary data shows that two tail-anchored transcription factors (NAC53 and 78) regulate proteasome gene expression during bacterial infection. More recent evidence, however, implicates that both NAC transcription factors are also required during bacterial infection, as the double mutant shows increased resistance towards Pseudomonas infection. This either implies that proteasome activation is also required during virulent expression or that NAC53/78 have additional target genes and act as negative regulators of defence. As both NAC transcription factors are localized to ER membrane via their c-terminal transmembrane domains, we hypothesize a mechanism that is conserved across yeast and animals how they are transported to nucleus, which we also plan to decipher within this funding period. Thus, we aim to characterize the role of both transcription factors in plant immunity, identify novel targets of both transcription factors and reveal how NAC53/78 are inserted into the ER membrane and translocated to the nucleus. All in all, we will provide new insights of how bacterial infection might influence the balance between up- and down regulation of proteasome function and reveal proteasome-independent roles of the NAC transcription factor pair.