The E1A proteins of all six human adenovirus subgroups target the p300/CBP acetyltransferases and the SAGA transcriptional regulatory complex.

The N-terminal/conserved region 1 (CR1) portion of the human adenovirus (Ad) 5 E1A protein was previously shown to inhibit growth in the simple eukaryote Saccharomyces cerevisiae. We now demonstrate that the corresponding regions of the E1A proteins of Ad3,-4,-9,-12, and -40, which represent the remaining five Ad subgroups, also inhibit yeast growth. These results suggest that the E1A proteins of all six human Ad subgroups share a common cellular target(s) conserved in yeast. Growth inhibition induced by either full-length or the N-terminal/CR1 portion of Ad5 E1A was relieved by coexpression of the E1A binding portions of the mammalian p300, CBP, and pCAF acetyltransferases. Similarly, growth inhibition by the N-terminal/CR1 portions of the other Ad E1A proteins was suppressed by expression of the same regions of CBP or pCAF known to bind Ad5 E1A. The physical interaction of each of the different Ad E1A proteins with CBP, p300, and pCAF was confirmed in vitro. Furthermore, deletion of the gene encoding yGcn5, the yeast homolog of pCAF and a subunit of the SAGA transcriptional regulatory complex, restored growth in yeast expressing each of the different Ad E1A proteins. This indicates that the SAGA complex is a conserved target of all Ad E1A proteins. Our results demonstrate for the first time that the p300, CBP, and pCAF acetyltransferases are common targets for the E1A proteins of all six human Ad subgroups, highlighting the importance of these interactions for E1A function.