Point mutations in the 5' ICR and anticodon region of a Drosophila tRNAArg gene decrease in vitro transcription.

We have examined the effects of various nucleotide substitutions in a Drosophila tRNAArg gene on in vitro transcription and stable transcription complex formation in Drosophila KcO and HeLa cell extracts. Substitutions in positions encoding the invariant G18 and G19 residues resulted in decreased transcription, however, the moderate decreases indicate that these nucleotides are not obligatory promoter recognition sites. An A21 to C21 mutation had no effect on transcription levels using homologous extract however, this mutant displayed decreased transcriptional abilities in HeLa cell extract. Nucleotide substitutions within the sequence encoding the anticodon led to a decrease in the transcription activity but not in the ability to form a stable transcription complex.