Isolation of tRNA isoacceptors by affinity chromatography with immobilized elongation factor Tu from Escherichia coli

Elongation factor Tu (EF-Tu) from E. coli was coupled to activated CH Sepharose 4B. The immobilized EF-Tu maintained most of the guanosine nucleotide binding activity, but its ability to bind aminoacyl-tRNA depended on the type of complex used in the coupling reaction. The EF-Tu . GTP . aminoacyl-tRNA . kirromycin complex yielded an immobilized factor that was much more active in binding aminoacyl-tRNA than that obtained by coupling EF-Tu . GDP or EF-Tu . GDP . kirromycin to CH Sepharose 4B. Like the free factor, the immobilized EF-Tu . GTP did bind aminoacyl-tRNAs, but not unacylated tRNAs or N-acylated-aminoacyl-tRNAs. The antibiotic kirromycin was used to obtain the rapid conversion of EF-Tu . GDP to EF-Tu . GTP and the release of aminoacyl-tRNA from the matrix-bound EF-Tu by GDP. When total tRNA was aminoacylated by one amino acid only, a column of immobilized EF-Tu . GTP . kirromycin allowed the isolation of the aminoacylated tRNA from bulk tRNA. A rapid and nearly quantitative recovery of highly purified tRNA isoacceptors for various amino acids was obtained in one chromatographic step. (C) 1997 Elsevier Science B.V.