title: Constitutive and inducible type 1 ribosome-inactivating proteins (RIPs) in elderberry (Sambucus nigra L.).
abstract: Two novel highly basic type 1 (single chain) ribosome-inactivating proteins (RIPs) with N-glycosidase activity have been found in elderberries (the fruits of Sambucus nigra L.). Mass spectrometry of these RIPs, which we named nigritins f1 and f2, gave Mr values of 24095 and 23 565, respectively. Both proteins strongly inhibited protein synthesis in rabbit reticulocyte lysates but were inactive against plant ribosomes. Both nigritins have a similar topological activity on pBlueScript SK+ DNA as that displayed by dianthin 30. Nigritin f1 is a constitutive RIP since it is present in both green and mature intact elderberries at nearly the same proportion with respect to total fruit protein. By contrast, nigritin f2 is inducible and only appeared in mature intact elderberries. Elderberries also contain two isoforms of a basic nigrin equivalent to the recently found basic nigrin b in elder bark (De Benito et al., FEBS Letters 413 (1997) 85-91). Our results indicate that probably not all plant RIPs exert the same biological function and that this may be determined by the physiological state of the tissue.
authors.affiliation: Departamento de Bioquímica y Biologia Molecular, Facultad de Ciencias, Universidad de Valladolid, Spain.
authors.forename: F M
authors.initials: FM
authors.lastname: de Benito
authors.forename: R
authors.initials: R
authors.lastname: Iglesias
authors.forename: J M
authors.initials: JM
authors.lastname: Ferreras
authors.forename: L
authors.initials: L
authors.lastname: Citores
authors.forename: E
authors.initials: E
authors.lastname: Camafeita
authors.forename: E
authors.initials: E
authors.lastname: Méndez
authors.forename: T
authors.initials: T
authors.lastname: Girbés
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D054788:Ribosome Inactivating Proteins; D054790:Ribosome Inactivating Proteins, Type 2
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D054790:Ribosome Inactivating Proteins, Type 2; D009699:N-Glycosyl Hydrolases; D054788:Ribosome Inactivating Proteins