Yeast expression vectors using RNA polymerase III promoters.

A series of Saccharomyces cerevisiae--Escherichia coli shuttle vectors is described in which small RNAs can be stably expressed in yeast from two different promoters for RNA polymerase III transcription. The vectors are available in either high- or low-copy-number forms with either URA3, HIS3, or TRP1 selection markers, and are based on a previously described set of plasmid vectors [Sikorski and Hieter, Genetics 122 (1989) 19-27]. Transcripts have structured pre-tRNA or RPR1 leaders fused to RNA corresponding to inserted sequences. Levels of RNA accumulation are dependent on plasmid copy number and the type of transcript.