title: Biochemical identification of proteasome-associated endonuclease activity in sunflower.
abstract: Proteasomes have been purified from sunflower hypocotyles. They elute with a molecular mass of 600 kDa from gel filtration columns and two-dimensional gel electrophoresis indicates that the complex contains at least 20 different protein subunits. Peptide microsequencing revealed the presence of four subunits homologous to subunits Beta2, Beta6, Alpha5 and Alpha6 of plant proteasomes. These proteasomes have chymotrypsin-like activity and the highly purified fraction of this complex is associated with an endonuclease activity hydrolyzing Tobacco mosaic virus RNA and Lettuce mosaic virus RNA with a cleavage pattern showing fragments of well-defined size. This is the first evidence of a RNA endonuclease activity associated with plant proteasomes.
authors.affiliation: UMR 1095, INRA Amélioration et Santé des Plantes, Université Blaise Pascal, Campus des Cézeaux, 24 Avenue des Landais, 63177 Aubière Cedex, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Ballut
authors.forename: Franck
authors.initials: F
authors.lastname: Petit
authors.forename: Said
authors.initials: S
authors.lastname: Mouzeyar
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Gall
authors.forename: Thierry
authors.initials: T
authors.lastname: Candresse
authors.forename: Peter
authors.initials: P
authors.lastname: Schmid
authors.forename: Paul
authors.initials: P
authors.lastname: Nicolas
authors.forename: Saloua
authors.initials: S
authors.lastname: Badaoui
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002918:Chymotrypsin / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004720:Endonucleases / Q000737:chemistry / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism; D006368:Helianthus / Q000737:chemistry / Q000201:enzymology*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D016415:Sequence Alignment
chemical_list: D009097:Multienzyme Complexes; D004720:Endonucleases; D004722:Endoribonucleases; D002918:Chymotrypsin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex