title: Ubiquitination of the tomato cell death suppressor Adi3 by the RING E3 ubiquitin ligase AdBiL.
abstract: Programmed cell death (PCD) is an organized process by which organisms selectively remove cells according to developmental needs or in response to biotic or abiotic stress. Despite recent efforts to understand mechanisms by which cell death takes place in plants, several gaps remain in our understanding of the molecular elements involved. The tomato PCD suppressor Adi3 is an AGC kinase that shares functional homology with the mammalian inhibitor of apoptosis PKB. Regulation of PKB stability, cell localization, and activation state is achieved through post-translational modifications such as ubiquitination. In an effort to understand the regulation of Adi3 function, we studied its interaction with the E3 ubiquitin ligase AdBiL. Using in vitro ubiquitination assays we show that AdBiL is an active E3 ubiquitin ligase using the E2 ubiquitin ligase UBC8 to ubiquitinate Adi3. Adi3 is also degraded in a proteasome-dependent manner. Our data draws additional parallels between Adi3 and PKB to support the functional relationship between these two PCD regulators.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843-2128, USA.
authors.forename: Julian
authors.initials: J
authors.lastname: Avila
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Devarenne
mesh_terms: D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D004795:Enzyme Stability; D018551:Solanum lycopersicum / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D054829:RING Finger Domains; D020798:Two-Hybrid System Techniques; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D051017:Apoptosis Regulatory Proteins; D010940:Plant Proteins; D044763:Ubiquitin-Conjugating Enzymes; C409686:ubiquitin-conjugating enzyme UBC8; D044767:Ubiquitin-Protein Ligases; D017346:Protein Serine-Threonine Kinases