title: PUB22 and PUB23 U-BOX E3 ligases directly ubiquitinate RPN6, a 26S proteasome lid subunit, for subsequent degradation in Arabidopsis thaliana.
abstract: Drought stress strongly affects plant growth and development, directly connected with crop yields, accordingly. However, related to the function of U-BOX E3 ligases, the underlying molecular mechanisms of desiccation stress response in plants are still largely unknown. Here we report that PUB22 and PUB23, two U-box E3 ligase homologs, tether ubiquitins to 19S proteasome regulatory particle (RP) subunit RPN6, leading to its degradation. RPN6 was identified as an interacting substrate of PUB22 by yeast two-hybrid screening, and in vitro pull-down assay confirmed that RPN6 interacts not only with PUB22, but also with PUB23. Both PUB22 and PUB23 were able to conjugate ubiquitins on RPN6 in vitro. Furthermore, RPN6 showed a shorter protein half-life in PUB22 overexpressing plants than in wild-type, besides RPN6 was significantly stabilized in pub22pub23 double knockout plants. Taken together, these results solidify a notion that PUB22 and PUB23 can alter the activity of 26S proteasome in response to drought stress.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: Seok Keun
authors.initials: SK
authors.lastname: Cho
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: Hansol
authors.initials: H
authors.lastname: Bae
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark.
authors.forename: Moon Young
authors.initials: MY
authors.lastname: Ryu
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Copenhagen, Denmark. Electronic address: swyang@plen.ku.dk.
authors.forename: Seong
authors.initials: S
authors.lastname: Wook Yang
authors.affiliation: Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, 120-749, South Korea. Electronic address: wtkim@yonsei.ac.kr.
authors.forename: Woo TaeK
authors.initials: WT
authors.lastname: Kim
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D055864:Droughts; D004795:Enzyme Stability; D055786:Gene Knockout Techniques; D017343:Genes, Plant; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits; D059748:Proteolysis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; D021122:Protein Subunits; D011994:Recombinant Proteins; C582896:PUB22 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
keywords: 26S proteasome lid complex; Drought stress; RPN6; U-BOX E3 ligase; Ubiquitin-proteasome system