Fluorescence characterization of the interaction of various transfer RNA species with elongation factor Tu multiplied by GTP: Evidence for a new functional role for elongation factor Tu in protein biosynthesis

• Published in: Biochemistry (Easton) Vol. 29; no. 18; pp. 4268 - 4277
• Main Authors: Janiak, F, Dell, V A, Abrahamson, J K, Watson, B S, Miller, D L, Johnson, A E
• Format: Journal Article
• Language: English
• Published: 01.01.1990
• ISSN: 0006-2960

The ubiquity of elongation factor Tu (EF-Tu)-dependent conformational changes in amino-acyl-tRNA (aa-tRNA) and the origin of the binding energy associated with aa-tRNA multiplied by EF-Tu multiplied by GTP ternary complex formation have been examined spectroscopically. Fluorescein was attached covalently to the 4-thiouridine base at position 8 (s super(4)U-8) in each of four elongator tRNAs (Ala, Met-m, Phe, and Val). Although the probes were chemically identical, their emission intensities in the free aa-tRNAs differed by nearly 3-fold, indicating that the dyes were in different environments and hence that the aa-tRNAs had different tertiary structures near s super(4)U-8. Upon association with EF-Tu multiplied by GTP, the emission intensities increased by 244%, 57%, or 15% for three aa-tRNAs due to a change in tRNA conformation; the fourth aa-tRNA exhibited no fluorescence change upon binding to EF-Tu multiplied by GTP.