title: Stored cysteine proteinases start globulin mobilization in protein bodies of embryonic axes and cotyledons during vetch (Vicia sativa L.) seed germination.
abstract: Inhibition of protein synthesis by cycloheximide during vetch seed germination, did not prevent globulin breakdown as indicated by a decrease in vicilin- and legumin-specific immunosignals on Western blots. Protein bodies isolated from embryo axes and cotyledons of dry vetch (Vicia sativa L.) seeds using a non-aqueous method were found to be free of cytoplasmic and organellar contaminations. Lysates of these purified protein bodies were capable of degrading globulins; this process was blocked by the cysteine proteinase (CPR) inhibitor iodoacetic acid. Protein bodies contained the papain-like CPR2 and CPR4, and the legumain-like CPR VsPB2. In vitro assays showed that albumin extracts from protein bodies degraded oligopeptide substrates in the PepTag-Assay and degraded the legumain substrate N-benzoyl-asparaginyl-p-nitroanilide. We conclude that, during germination, globulin mobilization is initiated by stored CPRs in protein bodies of embryonic axes as well as cotyledons, and that de-novo-formed proteolytic enzymes mainly mediate bulk degradation of stored globulin in cotyledons after germination.
authors.affiliation: Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, 06466 Gatersleben, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schlereth
authors.forename: D
authors.initials: D
authors.lastname: Standhardt
authors.forename: H P
authors.initials: HP
authors.lastname: Mock
authors.forename: K
authors.initials: K
authors.lastname: Müntz
mesh_terms: D001586:Benzoylarginine Nitroanilide; D001693:Biological Transport, Active; D015153:Blotting, Western; D002863:Chromogenic Compounds; D018548:Cotyledon / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D007887:Fabaceae / Q000187:drug effects / Q000378:metabolism*; D018525:Germination / Q000187:drug effects / Q000502:physiology*; D005916:Globulins / Q000187:drug effects / Q000378:metabolism*; D019807:Iodoacetic Acid / Q000037:antagonists & inhibitors; D010940:Plant Proteins / Q000378:metabolism; D010946:Plants, Medicinal; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D055314:Seed Storage Proteins; D012639:Seeds / Q000196:embryology / Q000378:metabolism; D000097793:Legumins; D000099240:Asparaginyl Endopeptidase
chemical_list: D001586:Benzoylarginine Nitroanilide; D002863:Chromogenic Compounds; D003513:Cycloheximide; D003546:Cysteine Endopeptidases; D005916:Globulins; D019807:Iodoacetic Acid; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D055314:Seed Storage Proteins; D000097793:Legumins; D000099240:Asparaginyl Endopeptidase; C015575:vicilin protein, plant