A specific lysine in c-Jun is required for transcriptional repression by E1A and is acetylated by p300

The adenovirus E1A protein regulates transcription of cellular genes via it s interaction with the transcriptional coactivators p300/CBP. The collagena se promoter activated by the c-Jun protein is repressed by E1A. Here we sho w that E1A repression is specific for c-Jun, as E1A does not repress the co llagenase promoter activated by the homologous transcription factor EB1. Us ing chimeras of c-Jun and EB1, we demonstrate that a 12 amino acid region i n the basic region of the c-Jun DNA-binding domain is essential for repress ion by E1A. Since repression requires the binding of p300 to E1A, we studie d the involvement of p300 acetyltransferase activity in the repression mech anism. We demonstrate that c-Jun is acetylated in vivo, and mutational anal ysis identified Lys271 in the c-Jun basic region to be essential for repres sion of the collagenase promoter by E1A. In addition, Lys271 is acetylated both in vitroandin vivo. These results suggest that the specific repression of the collagenase promoter by E1A involves acetylation of c-Jun.