Journal of Biological Chemistry
Volume 272, Issue 44, 31 October 1997, Pages 27635-27643
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NUCLEIC ACIDS, PROTEIN SYNTHESIS, AND MOLECULAR GENETICS
Structural Determinants in AUF1 Required for High Affinity Binding to A + U-rich Elements*

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AUF1 is an RNA-binding protein that contains two nonidentical RNA recognition motifs (RRMs). AUF1 binds to A + U-rich elements (AREs) with high affinity. The binding of AUF1 to AREs is believed to serve as a signal to an mRNA-processing pathway that degrades mRNAs encoding many cytokines, oncoproteins, and G protein-coupled receptors. Because the ARE binding activity of AUF1 appears central to the regulation of many important genes, we analyzed the domains of the protein that are important for this activity. Examination of the RNA binding affinity of various AUF1 mutants suggests that both RRMs may be required for binding to the human c-fos ARE. However, the two RRMs together are not sufficient. Highest affinity binding of AUF1 to an ARE requires an alanine-rich region of the N terminus and a short glutamine-rich region in the C terminus. In addition, the N terminus is required for dimerization of AUF1. However, AUF1 binds an ARE as a hexameric protein. Thus, protein-protein interactions are important for high affinity ARE binding activity of AUF1.

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*

This work was supported by National Institutes of Health (NIH) Grant CA52443, American Cancer Society Grant NP-884, and North Carolina Biotechnology Center (NCBC) Grant 9513-ARG-0002 (to G. B.). The core laboratories of the Comprehensive Cancer Center of Wake Forest University were supported in part by NIH Grant CA12197. PhosphorImager facilities were supported by NIH grant CA12197 and by NCBC grant 9510-IDG-1006.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.

Supported by NIH Grant T32-AI07401. Present address: Dept. of Biochemistry, McGill University, 3655 Drummond St., Montreal, Quebec H3G 1Y6, Canada.

§

Present address: Dept. of Physiology, Johns Hopkins School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205.

Supported by NIH Grant 1F32 DK08589, American Cancer Society Grant IRG 198, and National Science Foundation Grant MCB-9629732.