Recruitment of TRRAP required for oncogenic transformation by E1A.

TRRAP links Myc with histone acetylases and appears to be an important mediator of its oncogenic function. Here we show that interaction with TRRAP is required for cellular transformation not only by Myc, but also by the adenovirus E1A protein. Substitution of the 262 N-terminal residues of Myc with a small domain of E1A (residues 12-54) restores Myc transforming function. E1A(12-54) contains a TRRAP-interaction domain, that recruits TRRAP to either E1A-Myc chimeras, or the native 12S E1A protein. Overexpression of a competing TRRAP fragment in vivo blocks interaction of cellular TRRAP with either E1A-Myc or E1A, and suppresses cellular transformation by both oncoproteins. Moreover, E1A(Delta26-35) that fails to bind TRRAP but is capable of binding the Retinoblastoma (Rb)-family and p300/CBP proteins is defective in cellular immortalization, transformation and cell cycle deregulation. Thus in addition to disrupting Rb and p300/CBP functions, E1A must recruit TRRAP to transform cells.     

Adenovirus E1b-58 kD antigen binds to p53 during infection of rodent cells: evidence for an N-terminal binding site on p53.

We show using mild extraction procedures that the p53 proto-oncogene forms a complex with adenovirus 5 E1b-58 kD during infection. These complexes are detected as coimmunoprecipitates from radiolabeled extracts of adenovirus infected cells on SDS-PAGE. Furthermore, adenovirus mutants with defects in E1b-58 kD fail to form complexes, whereas mutants in other early region genes still show evidence of complex. Using a panel of monoclonal antibodies to mouse p53, we show that antibodies reacting with N-terminal epitopes on p53, displace E1b-58 kD. This result suggests that E1b-58 kD binds to an N-terminal region of mouse p53. In addition, in a transient transfection assay in monkey COS cells, we show that an N-terminal deletion mutant of mouse p53 does not bind to E1b-58 kD but wild-type mouse p53 does bind. This result again suggests that E1b-58 kD binds an N-terminal determinant on p53.