JBC, Vol. 250, Issue 21, 8399-8403, Nov, 1975
A novel function of Escherichia coli transfer RNA nucleotidyltransferase. Biosynthesis of the C-C-A sequence in a phage T4 transfer RNA precursor
F. J. Schmidt
The biosynthesis of the phage T4-coded proline and serine transfer RNA
species proceeds through a precursor RNA containing both tRNA sequences.
Neither tRNA sequence in the precursor RNA contains the 3'-terminal C-C-A
common to all mature tRNAs. Seidman and McClain ((1975) Proc. Natl. Acad.
Sci. U. S. A. 72, 1491-1495) have proposed that the C-C-A sequence is added
to serine tRNA while it is still part of the large precursor RNA. In the
present work, I show that, in vitro, a purified preparation of Escherichia
coli tRNA nucleotidyltransferase (EC 2.7.7.25) accurately synthesized
3'-terminal C-C-A in the serine tRNA portion of the precursor RNA. This
result establishes a role of tRNA nucleotidyltransferase in the
biosynthesis of the phage T4 serine tRNA. The finding that tRNA
nucleotidyltransferase utilizes the large precursor RNA as a substrate
represents a novel function of the enzyme.