DNA-Mediated Transfer of an RNA Polymerase II Gene: Reversion of the Temperature-Sensitive Hamster Cell Cycle Mutant TsAF8 by Mammalian DNA

Treatment of the TsAF8 temperature-sensitive (TS) mutant of Syrian hamster BHK-21 cells, with calcium phosphate precipitates of genomic TS/sup +/ DNAs from a variety of mammalian cell lines permitted the selection of TS/sup +/ colonies at 40/sup 0/C. TS/sup +/ transformation events were distinguished from spontaneous TS/sup +/ reversions in experiments in which ..cap alpha..-amanitin-sensitive (Ama/sup s/) TS/sup +/ DNA was used to transform an AMA/sup R/ derivative of TsAF8 cells and Ama/sup R/ TS/sup +/ DNA was used to transform Ama/sup s/ TsAF8 cells. In each case it was possible to demonstrate the unselected acquisition of the appropriate Ama/sup s/ or Ama/sup R/ phenotype with the selected TS/sup +/ allele. Each of these TS/sup +/ transformed cell lines when grown at 40/sup 0/C contained an RNA polymerase II activity with a sensitivity to inhibition by ..cap alpha..-amanitin characteristic of the particular DNA used to transform the TS cells, whereas at 34/sup 0/C the same cells contained a mixture of Ama/sup R/ and Ama/sup s/ polymerase II activities. Together, these data provide convincing evidence that the RNA polymerase II gene determining sensitivity to inhibition by ..cap alpha..-amanitin can be transferred to TsAF8 cells and that the TS defect in TsAF8more » is a polymerase II mutation.« less