Identification and Initial Characterization of a Specific Proteasome (Prosome) Associated RNase Activity

doi:10.1074/jbc.270.37.22023

Identification and Initial Characterization of a Specific Proteasome (Prosome) Associated RNase Activity (*)

From the Université Blaise Pascal, Clermont-Fd II, Biochimie, 24 Avenue des Landais, F-63177 Aubière Cedex, France and the
Station de Virologie et d'Immunologie Moléculaire, INRA, Domaine de Vilvert, 78350 Jouy-en-Josas, France

^§To whom correspondence should be addressed. Tel.: 33-73-40-74-25; Fax: 33-73-40-70-42.

Abstract

We have identified and characterized a specific nuclease activity to be tightly associated with proteasomes. Using tobacco mosaic virus RNA (TMV-RNA) as substrate to analyze and quantify the cleavage reaction, we supply several lines of evidence that this nuclease activity is an integral part of proteasomes. Thus, RNase activity was coincident with the elution profiles of proteasomes at each stage of purification. Proteasomal nuclease activity was resistant to strong dissociation conditions using 480 mM KCl, 0.5% sodium lauroylsarcosinate, and 6 M urea. This nuclease activity remained associated with an urea-resistant subcomplex of the proteasome comprising a specific set of proteins. Finally the digestion of TMV-RNA led to a well defined pattern of RNA fragments while 5 S ribosomal RNA and globin mRNA were not degraded. These results provide further evidence that proteasomes are able to discriminate between different RNAs, and the possible involvement of proteasomes in translation control is discussed.

Footnotes

↵* This work was supported in part by the Hasselblad Foundation, the Deutsche Forschungsgemeinschaft, the Ministère de la Recherche et Technologie, and the Conseil Régional Auvergne, France. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PAGE

polyacrylamide gel electrophoresis

mRNP

messenger ribonucleoprotein

TMV

tobacco mosaic virus

MOPS

4-morpholinepropanesulfonic acid

FPLC

fast protein liquid chromatography

pCp

cytidine 3′-5′-[5′-P]biphosphate.
↵²M-N. Pouch, F. Petit, J. Buri, Y. Briand, and H-P. Schmid, unpublished results.
- Received November 21, 1994.
- Revision received June 5, 1995.