Open AccessIncorporation of 1, N 6 ‐ethanoadenosine into the 3′ terminus of tRNA using T4 RNA ligase 1. Preparation of yeast tRNA Phe derivatives
Author(s) -
PAULSEN Harald,
WINTERMEYER Wolfgang
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb07889.x
Subject(s) - rna ligase , aminoacylation , transfer rna , cytidine , nucleoside , dna ligase , nucleotide , stereochemistry , chemistry , rna , biochemistry , enzyme , gene
The 3′‐terminal A‐C‐C‐A sequence of yeast tRNA Phe has been modified by replacing either adenosine 76 or 73 with the fluorescent analogues 1, N 6 ‐ethenoadenosine (ɛA) or 2‐aza‐1, N 6 ‐ethenoadenosine (aza‐ɛA). T4 RNA ligase was used to join the nucleoside 3′,5′‐bisphosphates to the 3′ end of the tRNA which was shortened by one [tRNA Phe (‐A)] or four [tRNA Phe (‐ACCA)] nucleotides. It was found that the base‐paired 3′‐terminal cytidine 72 in tRNA Phe (‐ACCA) is a more efficient acceptor in the ligation reaction than the unpaired cytidine 75 at the A‐C‐C terminus of tRNA Phe (‐A). This finding indicates that the mobility of the accepting nucleoside substantially influences the ligation reaction, the efficiency being higher the lower the mobility. This conclusion is corroborated by the observation that the ligation reaction with the double‐stranded substrate exhibits a positive temperature dependence rather than a negative one as found for single‐stranded acceptors. The replacement of the 3′‐terminal adenosine 76 with ɛA and aza‐ɛA leads to moderately fluorescent tRNA Phe derivatives, which are inactive in the aminoacylation reaction. A number of other tRNAs (Met, Ser, Glu, Lys and Leu‐specific tRNAs both from yeast and Escherichia coli ) are also inactivated by ɛA incorporation. Replacement of adenosine 73 followed by repair of the C‐C‐A end using nucleotidyl transferase leads to tRNA Phe derivatives which are fully active in the aminoacylation reaction and in polyphenylalanine synthesis. The fluorescence of ɛA and aza‐ɛA at position 73 is virtually completely quenched, suggesting a stacked arrangement of bases around this position. There is no fluorescence increase when the ɛA‐labeled tRNA Phe is complexed with phenylalanyl‐tRNA synthetase, elongation factor Tu, or ribosomes. These observations indicate that the stacked conformation of the 3′ terminus is not changed appreciably in these complexes.