The N Terminus of Eukaryotic Translation Elongation Factor 3 Interacts with 18 S rRNA and 80 S Ribosomes*
Abstract
Elongation factor-3 (EF-3) is an essential fungal-specific translation factor which exhibits a strong ribosome-dependent ATPase activity and has sequence homologies that may predict domains critical for its role in protein synthesis, including a domain at the N terminus, which exhibits sequence homology with Escherichia coli ribosomal protein S5. A portion of the N terminus of Saccharomyces cerevisiaeEF-3 (spanning the S5 homology region) has been cloned, expressed, and purified from E. coli. UV cross-linking experiments revealed that the N-terminal EF-3 protein (N-term EF-3) can be specifically cross-linked to 18 S rRNA. Filter-binding assays confirmed these data, and also established that the interaction has aK d ∼238 nm. Additional evidence shows that N-term EF-3 is able to associate with yeast ribosomes and inhibit the ribosome-dependent ATPase activity of native EF-3. These data taken together suggest that at least one of the ribosome-binding sites of EF-3 is located at the N terminus.
Footnotes
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↵* 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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↵‡ To whom correspondence should be addressed: RNA Research Group, Dept. of Molecular Recognition, SmithKline Beecham Pharmaceuticals, 709 Swedeland Rd., King of Prussia, PA 19406. Tel.: 610-270-5865; Fax: 610-270-5860; Email: Richard_R_Gontarek{at}sbphrd.com.
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↵§ Current address: RiboTargets, Cambridge, England.
- Received September 22, 1997.
- Revision received January 23, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
