Nucleic Acids Research, 1986, Vol. 14, No. 11 4659-4672
© 1986
Articles |
Fluorine-19 nuclear magnetic resonance study of codonanticodon interaction in 5-fluorouracil-substituted E. coli transfer RNAs*
Department of Biochemistry and Biophysics, Iowa State University Ames, IA 50011, USA
To whom correspondence should be addressed
Received March 18, 1986. Accepted May 5, 1986.
Codonanticodon interaction was investigated in fully active 5-fluorouracil-substituted E. coll tRNAYal (anticodon FAC) by 19F NMR spectroscopy. Binding of the codon GpUpA results in the upfield shift of a 19F resonance at 3.9'ppm in the central region of the 19F NMR spectrum, whereas trinucleotides not complementary to the anticodon have no effect. The same 19F resonance shifts upfield upon formation of an anticodon-anticodon dimer between the 19F-labeled tRNA and E. coll tRNA2Tyr (anticodon QUA). These results permit assignment of the peak at 3.9 ppm to the 5-fluorouracil at position 34 in the anticodon of fluorouracil-substituted tRNA1Ya1. The methionine codon ApUpG also causes a sequence-specific upfield shift of a peak in the central part of the 19F NMR spectrum of fluorinated E. coli tRNAmMet. However, ApUpG has no effect on the 19F spectrum of 19F-labeled E. coli tRNArMet, indicating possible conformational differences between the anti-codon loop of initiator and chain-elongating methionine tRNAs. 19F NMR experiments detect no binding of CpGpApA to the complementary FpFpCpG (replaces Tp
pCpG) in the T-loop of 5-fluorouracil-substituted tRNA1Yal, in the presence or absence of codon, suggesting that the tertiary interactions between the T- and D-loops are not disrupted by codon-anticodon interactions.
+Journal Paper No. J-11939 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA. Project No. 2566.
*Present address: Department of Chemistry, University of California-Berkeley, Berkeley, CA 94720, USA.