title: Involvement of proteasomal subunits zeta and iota in RNA degradation.
abstract: We have identified two distinct subunits of 20 S proteasomes that are associated with RNase activity. Proteasome subunits zeta and iota, eluted from two-dimensional Western blots, hydrolysed tobacco mosaic virus RNA, whereas none of the other subunits degraded this substrate under the same conditions. Additionally, proteasomes were dissociated by 6 M urea, and subunit zeta, containing the highest RNase activity, was isolated by anion-exchange chromatography and gel filtration. Purified subunit zeta migrated as a single spot on two-dimensional PAGE with a molecular mass of approx. 28 kDa. Addition of anti-(subunit zeta) antibodies led to the co-precipitation of this proteasome subunit and nuclease activity. This is the first evidence that proteasomal alpha-type subunits are associated with an enzymic activity, and our results provide further evidence that proteasomes may be involved in cellular RNA metabolism.
authors.affiliation: Université Blaise Pascal, Clermont-Ferrand II, Aubière, France.
authors.forename: F
authors.initials: F
authors.lastname: Petit
authors.forename: A S
authors.initials: AS
authors.lastname: Jarrousse
authors.forename: B
authors.initials: B
authors.lastname: Dahlmann
authors.forename: A
authors.initials: A
authors.lastname: Sobek
authors.forename: K B
authors.initials: KB
authors.lastname: Hendil
authors.forename: J
authors.initials: J
authors.lastname: Buri
authors.forename: Y
authors.initials: Y
authors.lastname: Briand
authors.forename: H P
authors.initials: HP
authors.lastname: Schmid
mesh_terms: D000818:Animals; D002417:Cattle; D003546:Cysteine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D006868:Hydrolysis; D008099:Liver / Q000201:enzymology; D009097:Multienzyme Complexes / Q000302:isolation & purification / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012367:RNA, Viral / Q000378:metabolism*; D012260:Ribonucleases / Q000378:metabolism; D014027:Tobacco Mosaic Virus / Q000235:genetics
chemical_list: D009097:Multienzyme Complexes; D012367:RNA, Viral; D012260:Ribonucleases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex