Purification, gene cloning, and gene disruption of the transcription elongation factor S-II in Saccharomyces cerevisiae.

Saccharomyces cerevisiae S-II was purified to near homogeneity as a protein stimulating RNA polymerase II. Four of seven lysyl endopeptidase-digested fragments of S-II were located in the PPR2 sequence reported previously. Analysis of a genomic clone of S-II revealed that S-II and PPR2 are the same protein consisting of 309 amino acid residues, and frame shifts were found in the sequence of PPR2 gene reported previously. Yeast S-II and mouse S-II showed high similarity in their amino acid sequences, especially in their amino-terminal and carboxyl-terminal regions. A gene disruption experiment showed that an S-II null mutant was not lethal under usual growth conditions, indicating that S-II is not essential for the growth of yeast.