J. Biol. Chem., Vol. 258, Issue 7, 4279-4284, 04, 1983
Transfer RNA pyrophosphorolysis with CTP(ATP):tRNA nucleotidyltransferase. A direct route to tRNAs modified at the 3' terminus
TA Francis, GM Ehrenfeld, MR Gregory and SM Hecht
The pyrophosphorolysis of tRNA by yeast CTP-(ATP):tRNA
nucleotidyltransferase has been studied in an effort to define the behavior
of the enzyme and the experimental parameters that lead to net loss of the
3'-terminal nucleotide or to nucleotide exchange. It was found that removal
of AMP from the terminus of tRNA proceeded optimally at 1.0 mM PPi;
incorporation of 2'- or 3'-dAMP was also studied and shown to proceed
optimally at a 6.0 mM concentration of deoxynucleoside triphosphate. CTP
was shown to inhibit the pyrophosphorolysis and nucleotide exchange
observed when starting from intact tRNA, but apparently not by inhibiting
removal of CMP from tRNA missing the 3'- terminal adenosine moiety. The
optimized conditions for nucleotide exchange were used for the preparative
conversion of tRNAs to species terminating in 2'- and 3'-deoxyadenosine.