Gene Cloning and Mutant Isolation of Subunits of RNA Polymerases in the Yeast Saccharomyces Cerevisiae
Compared to the bacterial situation, the transcriptional machinery of eukaryotes is remarkably complex. This complexity is evident at three levels. First, there is a multiplicity of RNA polymerases (one mitochondrial enzyme and three nuclear enzymes, the latter being designated as RNA polymerases A, B, and C or I, II, and III),* whereas there is only one enzyme in all bacteria and archebacteria thus far analyzed. Each RNA polymerase has a distinct gene specificity, with RNA polymerase A (which is nucleolar) synthesizing the large ribosomal RNA, polymerase B (which is the most sensitive to a amanitin) producing messenger RNAs, and polymerase C synthesizing small RNAs, such as 5S RNA and transfer RNAs. Second, each nuclear RNA polymerase appears to have more different polypeptide subunits than the bacterial enzyme. Third, purified eukaryotic RNA polymerases are unable to carry the accurate transcription of isolated genes in vitro, which is in contrast to bacterial holoenzymes. There appears to be no equivalent to a subunits in eukaryotic RNA polymerases, where additional proteins (transcription factors) are required to reconstitute specific transcription.
KeywordsNull Allele Mutant Allele Replicative Plasmid Haploid Strain Mutant Isolation
Unable to display preview. Download preview PDF.
- 6.Miller, J.H., I.V. Claeus, J.B. Kirschbaum, S. Nasi, S. Van Der Eisacker, B. Molholt, G. Gross, D.A. Fields, and E.K.F. Bautz (1976) Altered RNA polymerases resulting from temperature-sensitive mutations in the rif region of the E. coll genome. In RNA Polymerase, R. Losick and M. Chamberlin, eds. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, pp. 519–538.Google Scholar
- 10.Rothstein, R.L. (1983) One step disruption in yeast. In Methods in Enzymology, Vol. 101, L. Grossman and K. Moldave, eds. Academic Press, Inc., New York, pp. 202–210.Google Scholar
- 14.Shortle, D., and D. Botsteln (1983) Directed mutagenesis with sodium bisulfite. In Methods in Enzymology, Vol. 100, L. Grossman and K. Moldave, eds. Academic Press, Inc., New York, pp. 457–468.Google Scholar