Poking a hole in mitochondria

The authors have found that the two yeast mRNA capping enzymes, Cet1p and Ceg1p, are potent in vitro inhibitors of transcription. Cet1p, stimulated by its Ceg1p binding partner, stalled transcription by blocking reinitiation at already activated promoters. Conversely, elimination of Cet1p in vivo stimulated transcription. Although Cet1p is the first general repressor found to act at reinitiation, this step is well suited for transcripNative and recombinant capping enzymes block transcription in vitro. Te m ps t/E ls ev ie r