BS69 : A novel adenovirus E1A-associated protein that inhibits E1A transactivation

Abstract

The adenovirus ElA gene products are nuclear phosphoproteins that can transactivate the other adenovirus early genes as well as several cellular genes, and can transform primary rodent cells in culture. Transformation and transactivation by ElA proteins is most likely to be mediated through binding to several cellular proteins, including the retinoblastoma gene product pRb, the pRb-related p107 and p130, and the TATA box binding protein TBP. We report here the cloning of BS69, a novel protein that specifically interacts with adenovirus 5 ElA. BS69 has no significant homology to known proteins and requires the region that is unique to the large (289R) ElA protein for high affinity binding. BS69 and ElA proteins coimmunoprecipitate in adenovirus-transformed 293 cells, indicating that these proteins also interact in vivo. BS69 specifically inhibits transactivation by the 289R ElA protein, but not by the 243R ElA protein. BS69 also suppressed the ElA-stimulated transcription of the retinoic acid receptor in COS cells, but did not affect the cellular ElA-like activity that is present in embryonic carcinoma cells. Our data indicate that BS69 is a novel and specific suppressor of ElA-activated transcription.