title: RPT2a, a 26S proteasome AAA-ATPase, is directly involved in Arabidopsis CC-NBS-LRR protein uni-1D-induced signaling pathways.
abstract: Arabidopsis semi-dominant uni-1D shows both constitutive defense responses and diverse morphological defects. In particular, uni-1D homozygote (uni-1D) mutants exhibit severe phenotypes including not only highly up-regulated pathogenesis related-1(PR-1) gene expression, but also lethality in the early stage of true leaf formation after germination. The gene responsible for the mutant encodes a coiled-coil-nucleotide-binding site-leucine-rich repeat (CC-NBS-LRR)-type R protein that functions in the recognition of pathogen and the triggering of defense responses. However, the molecular basis of how uni-1D can induce these phenotypes was unknown. In this study, we isolated the regulatory particle triple-ATPase (RPT) subunits 2a and 2b, base components of the 19S regulatory particle in the 26S proteasome, as uni-1D-interacting proteins using yeast two-hybrid screening. Genetic studies showed that crossing with the rpt2a mutant reduces the level of uni-1D-induced PR-1 gene expression and suppresses the lethality of uni-1D, by leading to restoration of lost expression of the WUSCHEL gene, which functions to maintain meristem activity, in the shoot apical mersitem of uni-1D. These results suggest that RPT2a is a major interacting partner of uni-1D/UNI, and that the interaction between uni-1D and RPT2a is responsible for activating both morphology and defense signals.
authors.affiliation: Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, 630-0192 Japan.
authors.forename: KwiMi
authors.initials: K
authors.lastname: Chung
authors.forename: Masao
authors.initials: M
authors.lastname: Tasaka
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003583:Cytokinins / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics; D020156:Salicylic Acid / Q000378:metabolism; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D003583:Cytokinins; D018749:RNA, Plant; C487429:RPT2a protein, Arabidopsis; C532244:UNI protein, Arabidopsis; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D020156:Salicylic Acid