title: RIP and RALyase cleave the sarcin/ricin domain, a critical domain for ribosome function, during senescence of wheat coleoptiles.
abstract: Type-I ribosome-inactivating protein (RIP), which is found in many plants, catalyzes depurination of a specific adenine in the sarcin/ricin domain (SRD) of the large rRNA causing loss of ribosomal activity. Previously, we found a RNA apurinic site-specific lyase (RALyase) that catalytically cleaved the phosphodiester bond at the RIP-dependent depurination site by beta-elimination reaction. Here we show that both the RIP activity and RIP-RALyase-mediated cleavage of SRD in the cytoplasmic ribosome were induced at the late stage of senescence of wheat coleoptiles. Following this process, tissue death was observed. Furthermore, transgenic tobacco plants expressing glucocorticoid-induced RIP developed senescence-like phenotype. Our results suggest that ribosome inactivation due to the cleavage of SRD by the inducible RIP and constitutively expressed RALyase may be a unique plant system that mediates programmed cell death at the late senescent stage.
authors.affiliation: Cell-free Science and Technology Research Center, The Venture Business Laboratory, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan. sawasaki@eng.ehime-u.ac.jp
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawasaki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishihara
authors.forename: Yaeta
authors.initials: Y
authors.lastname: Endo
mesh_terms: D001483:Base Sequence; D018548:Cotyledon / Q000201:enzymology / Q000276:immunology / Q000502:physiology*; D004722:Endoribonucleases / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000737:chemistry / Q000378:metabolism*; D054789:Ribosome Inactivating Proteins, Type 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012276:Ricin / Q000737:chemistry; D014026:Nicotiana / Q000235:genetics; D014908:Triticum / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
chemical_list: D005656:Fungal Proteins; D010940:Plant Proteins; D012335:RNA, Ribosomal; D054789:Ribosome Inactivating Proteins, Type 1; C031676:tritin protein, Triticum aestivum; C014801:alpha-sarcin; D012276:Ricin; D004722:Endoribonucleases; C402789:ribosomal RNA apurinic site specific lyase