NIPP-1, a Nuclear Inhibitory Subunit of Protein Phosphatase-1, Has RNA-binding Properties*
- Izabela Jagiello,
- Monique Beullens‡,
- Veerle Vulsteke,
- Stefaan Wera‡,
- Björn Sohlberg§,
- Willy Stalmans,
- Alexander von Gabain§ and
- Mathieu Bollen¶
- From the Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium and §Institute of Microbiology and Genetics, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
Abstract
NIPP-1 is a nuclear inhibitory subunit of protein phosphatase-1 with structural similarities to some proteins involved in RNA processing. We report here that baculovirus-expressed recombinant NIPP-1 displays RNA-binding properties, as revealed by North-Western analysis, by UV-mediated cross-linking, by RNA mobility-shift assays, and by chromatography on poly(U)-Sepharose. NIPP-1 preferentially bound to U-rich sequences, including RNA-destabilizing AUUUA motifs. NIPP-1 also associated with single-stranded DNA, but had no affinity for double-stranded DNA. The binding of NIPP-1 to RNA was blocked by antibodies directed against the COOH terminus of NIPP-1, but was not affected by prior phosphorylation of NIPP-1 with protein kinase A or casein kinase-2, which decreases the affinity of NIPP-1 for protein phosphatase-1. The catalytic subunit of protein phosphatase-1 did not bind to poly(U)-Sepharose, but it bound very tightly after complexation with NIPP-1. These data are in agreement with a function of NIPP-1 in targeting protein phosphatase-1 to RNA.
Footnotes
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↵* This work was supported by the Algemene Spaar- en Lijfrentekas, by the Belgian Fund for Medical Scientific Research (Grant G.0179.97), by a Flemish Concerted Research Action, and by grants of the Austrian Science Foundation FWF (to A. v. G.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ Postdoctoral Fellow of the Fund for Scientific Research-Flanders.
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↵¶ To whom correspondence should be addressed: Afdeling Biochemie, Campus Gasthuisberg KULeuven, B-3000 Leuven, Belgium. Tel.: 32-16-34-57-01; Fax: 32-16-34-59-95; E-mail: Mathieu.Bollen@med.KULeuven.ac.Be.
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↵1 The abbreviations used are: PP-1, protein phosphatase-1; PP-1C, catalytic subunit of PP-1; NIPP-1, nuclear inhibitor of protein phosphatase-1; PP-1NNIPP-1, complex of PP-1C and NIPP-1; snRNPs, small nuclear ribonucleoproteins; PAGE, polyacrylamide gel electrophoresis;ompA, outer membrane protein A.
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↵2 A. Van Eynde, I. Jagiello, M. Beullens, V. Vulsteke, S. Wera, W. Stalmans, and M. Bollen, unpublished data.
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↵3 V. Vulsteke, manuscript in preparation.
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- Received June 10, 1997.
