title: The RPN5 subunit of the 26s proteasome is essential for gametogenesis, sporophyte development, and complex assembly in Arabidopsis.
abstract: The 26S proteasome is an essential multicatalytic protease complex that degrades a wide range of intracellular proteins, especially those modified with ubiquitin. Arabidopsis thaliana and other plants use pairs of genes to encode most of the core subunits, with both of the isoforms often incorporated into the mature complex. Here, we show that the gene pair encoding the regulatory particle non-ATPase subunit (RPN5) has a unique role in proteasome function and Arabidopsis development. Homozygous rpn5a rpn5b mutants could not be generated due to a defect in male gametogenesis. While single rpn5b mutants appear wild-type, single rpn5a mutants display a host of morphogenic defects, including abnormal embryogenesis, partially deetiolated development in the dark, a severely dwarfed phenotype when grown in the light, and infertility. Proteasome complexes missing RPN5a are less stable in vitro, suggesting that some of the rpn5a defects are caused by altered complex integrity. The rpn5a phenotype could be rescued by expression of either RPN5a or RPN5b, indicating functional redundancy. However, abnormal phenotypes generated by overexpression implied that paralog-specific functions also exist. Collectively, the data point to a specific role for RPN5 in the plant 26S proteasome and suggest that its two paralogous genes in Arabidopsis have both redundant and unique roles in development.
authors.affiliation: Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Book
authors.forename: Jan
authors.initials: J
authors.lastname: Smalle
authors.forename: Kwang-Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: Peizhen
authors.initials: P
authors.lastname: Yang
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Walker
authors.forename: Sarah
authors.initials: S
authors.lastname: Casper
authors.forename: James H
authors.initials: JH
authors.lastname: Holmes
authors.forename: Laura A
authors.initials: LA
authors.lastname: Russo
authors.forename: Zachri W
authors.initials: ZW
authors.lastname: Buzzinotti
authors.forename: Pablo D
authors.initials: PD
authors.lastname: Jenik
authors.forename: Richard D
authors.initials: RD
authors.lastname: Vierstra
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D047108:Embryonic Development / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010641:Phenotype; D011058:Pollen / Q000235:genetics / Q000254:growth & development; D046988:Proteasome Endopeptidase Complex / Q000502:physiology*; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012639:Seeds / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D021122:Protein Subunits; C542040:RPN5 protein, Arabidopsis; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease