RNA polymerase II induced transcription of tRNA genes and processing of the mRNAs in yeast

Only 5'-halves were produced when the terminator sequence for RNA polymerase (pol) III transcription was inserted into the intron of yeast tRNA(Tyr) gene. If a promoter and a terminator for pol II transcription flanked it, the tRNA gene could be transcribed by pol II, but the transcripts could not be processed into mature tRNAs. In contrast, tRNA gene could also be transcribed by pol III and the transcripts could be processed into mature tRNAs even if a promoter and a terminator for pol II transcription flanked it. Pol II transcripts, modified with a self-cleaved hammerhead structure at 3'-end, were processed into mature tRNAs in the medium containing 100 mmol/L Mg2+, indicating that the 3'-long trailer sequence blocks the maturation of tRNA gene transcripts by pol II.