A nucleocytoplasmic-localized E3 ligase affects the NLR receptor stability.

Area of Science:

• Plant immunity
• Post-translational modifications
• Protein degradation

Background:

• Nucleotide-binding site and leucine-rich repeat receptors (NLRs) are crucial for plant immunity.
• Ubiquitination, mediated by E3 ligases like BOI, regulates NLR protein turnover.
• The subcellular localization and precise degradation pathway of L5, a CC-NBS-LRR protein, remain unclear.

Purpose of the Study:

• To investigate the subcellular localization of BOI-mediated ubiquitination and degradation of L5 in Nicotiana benthamiana.
• To elucidate the role of BOI and its homologs in regulating L5 protein levels.

Main Methods:

• In vitro ubiquitination assays.
• Subcellular localization studies using Nicotiana benthamiana.
• Analysis of L5 protein levels in the presence of BOI and its homologs.

Main Results:

• BOI directly interacts with and ubiquitinates L5.
• BOI exhibits nucleocytoplasmic localization and mediates the degradation of plasma membrane-localized L5 outside the nucleus.
• BOI, BRG1, and BRG3 function redundantly to negatively regulate L5 protein levels.

Conclusions:

• BOI targets L5 for proteasomal degradation at a subcellular location distinct from the nucleus.
• BOI and its homologs play a redundant role in controlling L5 protein homeostasis.
• This study expands the understanding of BOI's function, revealing multiple targets and diverse subcellular roles.