title: Cross-species divergence of the major recognition pathways of ubiquitylated substrates for ubiquitin/26S proteasome-mediated proteolysis.
abstract: The recognition of ubiquitylated substrates is an essential element of ubiquitin/26S proteasome-mediated proteolysis (UPP), which is mediated directly by the proteasome subunit RPN10 and/or RPN13, or indirectly by ubiquitin receptors containing ubiquitin-like and ubiquitin-associated domains. By pull-down and mutagenesis assays, we detected cross-species divergence of the major recognition pathways. RPN10 plays a major role in direct recognition in Arabidopsis and yeast based on the strong affinity for the long and K48-linked ubiquitin chains. In contrast, both the RPN10 and RPN13 homologs play major roles in humans. For indirect recognition, the RAD23 and DSK2 homologs (except for the human DSK2 homolog) are major receptors. The human RAD23 homolog is targeted to the 26S proteasome by the RPN10 and RPN13 homologs. In comparison, Arabidopsis uses UIM1 and UIM3 of RPN10 to bind DSK2 and RAD23, respectively. Yeast uses UIM in RPN10 and LRR in RPN1. Overall, multiple proteasome subunits are responsible for the direct and/or indirect recognition of ubiquitylated substrates in yeast and humans. In contrast, a single proteasome subunit, RPN10, is critical for both the direct and indirect recognition pathways in Arabidopsis. In agreement with these results, the accumulation of ubiquitylated substrates and severe pleiotropic phenotypes of vegetative and reproductive growth are associated with the loss of RPN10 function in an Arabidopsis T-DNA insertion mutant. This implies that the targeting and proteolysis of the critical regulators involved are affected. These results support a cross-species mechanistic and functional divergence of the major recognition pathways for ubiquitylated substrates of UPP.
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
authors.forename: Antony S
authors.initials: AS
authors.lastname: Fatimababy
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Lin
authors.forename: Raju
authors.initials: R
authors.lastname: Usharani
authors.forename: Ramalingam
authors.initials: R
authors.lastname: Radjacommare
authors.forename: Hsing-Ting
authors.initials: HT
authors.lastname: Wang
authors.forename: Hwang-Long
authors.initials: HL
authors.lastname: Tsai
authors.forename: Yenfen
authors.initials: Y
authors.lastname: Lee
authors.forename: Hongyong
authors.initials: H
authors.lastname: Fu
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013045:Species Specificity; D025801:Ubiquitin / Q000378:metabolism*; D014452:Ubiquitins / Q000378:metabolism
chemical_list: C500781:ADRM1 protein, human; D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C108125:DDI1 protein, S cerevisiae; D004268:DNA-Binding Proteins; C100415:DSK2 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C490846:RAD23 protein, S cerevisiae; C499663:RPN1 protein, S cerevisiae; C475163:RPN10 protein, Arabidopsis; C122019:RPN10 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D014452:Ubiquitins; C086985:RAD23A protein, human; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D045643:DNA Repair Enzymes