Site-directed mutagenesis of a tRNA gene: base alterations in the coding region affect transcription

Point mutations have been introduced in vitro in a cloned nematode tRNAPro gene. Four different mutant clones altered in the DNA that codes for tRNAPro have been isolated. Studies on the expression of the mutant genes by microinjection into Xenopus oocyte nuclei reveal that their activities as transcription templates are reduced. The results show that DNA sequences that code for the extra arm and the stem of the T-psi-C-G arm of the tRNAPro have an important role in the initiation of tRNA gene transcription.