title: Purification and characterization of serine proteases that exhibit caspase-like activity and are associated with programmed cell death in Avena sativa.
abstract: Victoria blight of Avena sativa (oat) is caused by the fungus Cochliobolus victoriae, which is pathogenic because of the production of the toxin victorin. The victorin-induced response in sensitive A. sativa has been characterized as a form of programmed cell death (PCD) and displays morphological and biochemical features similar to apoptosis, including chromatin condensation, DNA laddering, cell shrinkage, altered mitochondrial function, and ordered, substrate-specific proteolytic events. Victorin-induced proteolysis of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is shown to be prevented by caspase-specific and general protease inhibitors. Evidence is presented for a signaling cascade leading to Rubisco proteolysis that involves multiple proteases. Furthermore, two proteases that are apparently involved in the Rubisco proteolytic cascade were purified and characterized. These proteases exhibit caspase specificity and display amino acid sequences homologous to plant subtilisin-like Ser proteases. The proteases are constitutively present in an active form and are relocalized to the extracellular fluid after induction of PCD by either victorin or heat shock. The role of the enzymes as processive proteases involved in a signal cascade during the PCD response is discussed.
authors.affiliation: Department of Botany and Plant Pathology and Center for Gene Research and Biotechnology, Oregon State University, Corvallis 97331-2902, USA.
authors.forename: Warren C
authors.initials: WC
authors.lastname: Coffeen
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Wolpert
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001203:Ascomycota / Q000472:pathogenicity; D018554:Avena / Q000737:chemistry* / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D061945:Caspase Inhibitors; D020169:Caspases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005656:Fungal Proteins / Q000633:toxicity; D017343:Genes, Plant; D018869:Heat-Shock Response; D006493:Heparin / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009183:Mycotoxins / Q000633:toxicity; D010449:Peptide Mapping; D010935:Plant Diseases / Q000382:microbiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005656:Fungal Proteins; D009183:Mycotoxins; C094015:Victorin protein, Cochliobolus victoriae; D006493:Heparin; D012697:Serine Endopeptidases; D020169:Caspases; D012273:Ribulose-Bisphosphate Carboxylase