The 3′-End of tRNA and Its Role in Protein Biosynthesis

Authors

  • Prof. Dr. Stanislav Chládek,

    1. Michigan Cancer Foundation, Chemistry Department, 110 East Warren Avenue, Detroit, MI 48 201 (USA)
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  • Prof. Dr. Mathias Sprinzl

    Corresponding author
    1. Laboratorium für Biochemie der Universität, Universitätsstrasse 30, D-8580 Bayreuth (FRG)
    • Laboratorium für Biochemie der Universität, Universitätsstrasse 30, D-8580 Bayreuth (FRG)
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  • This review was written during a sabbatical stay of S. C. at the Laboratorium für Biochemie der Universität Bayreuth.

Abstract

In the course of protein biosynthesis, the 3′-ends of aminoacyl-tRNA (aa-tRNA) and peptidyl-tRNA specifically interact with macromolecules of the protein biosynthesis machinery. The 3′-end of tRNA consists of an invariant C-C-A single strand. Interaction of the aminoacyl-tRNA 3′-end with elongation factor Tu (EF-Tu) containing bound GTP is necessary for the formation of the aa-tRNA·EF-Tu·GTP complex and, after the complex binds to the ribosome, for the GTP hydrolysis. This process is followed by the specific binding of the aminoacyl-tRNA 3′-end to the aminoacyl (A) site of the ribosome. In this review, a model is proposed that involves Watson-Crick base pairing of the C[BOND]C sequence of the aminoacyl-tRNA 3′-end with a specific G[BOND]G sequence of the ribosomal 23S RNA. Similarly, peptidyl-tRNA binds with its 3′-end to the peptidyl (P) site of the ribosome. This binding may also involve Watson-Crick base pairing of the C-C-A sequence with a complementary sequence of 23S RNA. It is proposed that peptide bond formation is catalyzed by a functional site of the 23S RNA located near the 3′-ends of aminoacyl-tRNA and peptidyl-tRNA. A model is suggested in which two loops of the 23S RNA, brought into close proximity via folding, are involved both in binding the 3′-ends of the tRNAs and in catalyzing peptide bond formation. This model presumes a dynamic structure for ribosomal RNA, which is modulated by interaction with elongation factors and ribosomal proteins.

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