title: Expression and localisation of a senescence-associated KDEL-cysteine protease from Lilium longiflorum tepals.
abstract: Senescence is a tightly regulated process and both compartmentalisation and regulated activation of degradative enzymes is critical to avoid premature cellular destruction. Proteolysis is a key process in senescent tissues, linked to disassembly of cellular contents and nutrient remobilisation. Cysteine proteases are responsible for most proteolytic activity in senescent petals, encoded by a gene family comprising both senescence-specific and senescence up-regulated genes. KDEL cysteine proteases are present in senescent petals of several species. Isoforms from endosperm tissue localise to ricinosomes: cytosol acidification following vacuole rupture results in ricinosome rupture and activation of the KDEL proteases from an inactive proform. Here data show that a Lilium longiflorum KDEL protease gene (LlCYP) is transcriptionally up-regulated, and a KDEL cysteine protease antibody reveals post-translational processing in senescent petals. Plants over-expressing LlCYP lacking the KDEL sequence show reduced growth and early senescence. Immunogold staining and confocal analyses indicate that in young tissues the protein is retained in the ER, while during floral senescence it is localised to the vacuole. Our data therefore suggest that the vacuole may be the site of action for at least this KDEL cysteine protease during tepal senescence.
authors.affiliation: Department of Agricolture, food and environment, University of Pisa, Via del Borghetto 80, 56124, Italy. Electronic address: riccardobattelli@gmail.com.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Battelli
authors.forename: Lara
authors.initials: L
authors.lastname: Lombardi
authors.forename: Piero
authors.initials: P
authors.lastname: Picciarelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Lorenzi
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Frigerio
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Rogers
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D057056:Cysteine Proteases / Q000235:genetics* / Q000378:metabolism; D035264:Flowers / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D027762:Lilium / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D021382:Protein Sorting Signals / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000201:enzymology / Q000648:ultrastructure
chemical_list: D008164:Luminescent Proteins; D009842:Oligopeptides; D010940:Plant Proteins; D021382:Protein Sorting Signals; C073762:lysyl-aspartyl-glutamyl-leucine; D057056:Cysteine Proteases
keywords: Cysteine proteases; Endoplasmic reticulum; Lilium; Petal senescence; Subcellular localisation; Vacuole