TheKIN28Gene is Required both for RNA Polymerase II Mediated Transcription and Phosphorylation of the Rpb1p CTD

Abstract

Kin28p, associated with cyclin Ccl1p, is a putative cyclin-dependent kinase (CDK) of the p34cdc2family inSaccharomyces cerevisiae. Search for mutations co-lethal (synmutations) with akin28thermosensitive mutation (kin28-ts3) has uncovered genetic interactions between geneKIN28and genesRAD3, SIN4, STI1andCDC37. The genetic interaction betweenKIN28and theCDC37cell division cycle gene suggests that a connection exists between the activity of CDK-Kin28p and cell-cycle progression. BothRAD3andSIN4gene products are implicated in the RNA polymerase II transcription process. Here we show that RNA polymerase II transcription is drastically reduced in akin28-tsmutant, at restrictive temperature. This impairment correlates with a markedly decreased phosphorylation of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Rpb1p). Thus, the Kin28 gene product is requiredin vivofor RNA polymerase II phosphorylation and transcriptional activity as recently suggested by experiments using anin vitroreconstituted system.