Functional conservation of RNA polymerase II in fission and budding yeasts

The complementary DNAs of the 12 subunits of fission yeast (Schizosaccharom yces pombe) RNA polymerase II were expressed from strong promoters in Sacch aromyces cerevisine and tested for heterospecific complementation by monito ring their ability to replace in vivo the null, mutants of the correspondin g host genes. Rpb1 and Rpb2, the two largest subunits and Rpb8, a small sub unit shared by all three polymerases, failed to support growth in S, cerevi siae. The remaining nine subunits were all proficient for heterospecific co mplementation and led in most cases to a wild-type level of growth. The two alpha-like subunits (Rpb3 and Rpb11), however, did not support growth at h igh (37 degrees C) or low (25 degrees C) temperatures. Ln the case of Rpb3, growth was restored by increasing the gene dosage of the host Rpb11 or Rpb 10 subunits, confirming previous evidence of a close genetic interaction be tween these three subunits. (C) 2000 Academic Press.