BRCA1 protein is linked to the RNA polymerase II holoenzyme complex via RNA helicase A

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Abstract
The breast cancer specific tumour suppressor protein, BRCA1 (refs 1,2), activates transcription when linked with a DNA-binding domain3,4 and is a component of the RNA polymerase II (Pol II) holoenzyme5,6. We show here that RNA helicase A (RHA) protein7,8 links BRCA1 to the holoenzyme complex. The region of BRCA1 which interacts with RHA and, thus, the holoenzyme complex, corresponds to subregions of the BRCT domain of BRCA1 ( ref. 9). This interaction was shown to occur in yeast nuclei, and expression in human cells of a truncated RHA molecule which retains binding to BRCA1 inhibited transcriptional activation mediated by the BRCA1 carboxy terminus. These data are the first to identify a specific protein interaction with the BRCA1 C-terminal domain and are consistent with the model that BRCA1 functions as a transcriptional coactivator.