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Poly(A)-binding protein interaction with eIF4G stimulates picornavirus IRES-dependent translation

Published online by Cambridge University Press:  11 January 2002

YURI V. SVITKIN
Affiliation:
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada
HIROAKI IMATAKA
Affiliation:
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada
KIANOUSH KHALEGHPOUR
Affiliation:
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada Present address: The Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada.
AVAK KAHVEJIAN
Affiliation:
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada
HANS-DIETER LIEBIG
Affiliation:
Department of Biochemistry, Medical Faculty, University of Vienna, A1090, Vienna, Austria
NAHUM SONENBERG
Affiliation:
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec H3G 1Y6, Canada
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Abstract

The eukaryotic mRNA 3′ poly(A) tail and the 5′ cap cooperate to synergistically enhance translation. This interaction is mediated, at least in part, by eIF4G, which bridges the mRNA termini by simultaneous binding the poly(A)-binding protein (PABP) and the cap-binding protein, eIF4E. The poly(A) tail also stimulates translation from the internal ribosome binding sites (IRES) of a number of picornaviruses. eIF4G is likely to mediate this translational stimulation through its direct interaction with the IRES. Here, we support this hypothesis by cleaving eIF4G to separate the PABP-binding site from the portion that promotes internal initiation. eIF4G cleavage abrogates the stimulatory effect of poly(A) tail on translation. In addition, translation in extracts in which eIF4G is cleaved is resistant to inhibition by the PABP-binding protein 2 (Paip2). The eIF4G cleavage-induced loss of the stimulatory effect of poly(A) on translation was mimicked by the addition of the C-terminal portion of eIF4G. Thus, PABP stimulates picornavirus translation through its interaction with eIF4G.

Type
Research Article
Information
RNA , Volume 7 , Issue 12 , December 2001 , pp. 1743 - 1752
Copyright
2001 RNA Society

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