Identification of families of overlapping polypeptides coded by early “transforming” gene region 1 of human adenovirus type 2

Abstract

Antisera against four lines of adenovirus 2-transformed rat cells, including F17 cells which contain only early gene region 1 (map position 1.5–11) (the transforming region), immunoprecipitate major polypeptides of 53,000 (53K) and 15,000 (15K) daltons ( Gilead, Y.-H. Jeng, W. S. M. Wold, K. Sugawara, H. M. Rho, M. L. Harter, and M. Green, 1976, Nature (London) 264,263–266; W. S. M. Wold and M. Green, 1976, J. Virol. 30,297–310). We show here that the 53Ks precipitated by three of these antisera as well as Adl-SV40 induced hamster tumor sera all have identical two-dimensional tryptic [ 35S]Met-peptide maps. Similarly, all 15Ks precipitated by these antisera have identical maps. Tryptic and chymotryptic maps demonstrate that most if not all of the [ 35S]Met-peptides of 15K are shared by 53K. Recent tryptic peptide maps (D. Halbert, D. Spector, H. J. Raskas, W. S. M. Wold, and M. Green, unpublished data) prove that the 53K corresponds to a 53K translated in vitro from a 22S RNA derived from map positions 4.5–11 (D. Halbert, D. Spector, and H. J. Raskas, J. Virol., in press). Thus, both the 53K and 15K are coded within map position 4.5–11. Four [ 35S]Met-labeled polypeptides of 40K–50K, specific to Ad2 early infected human cells, were isolated in O'Farrell-type 2D gels. These polypeptides are coded within map position 1.5-4.5 (D. Halbert, D. Spector, and H. J. Raskas, J. Virol., in press; D. Halbert, D. Spector, H. J. Raskas, W. S. M. Wold, and M. Green, unpublished data). As expected, our tryptic and chymotryptic peptide maps of these four polypeptides indicate no relationship to 53K or 15K. Two of the 40K–50K polypeptides are highly related, the other two are highly related, and all four are partially related. In addition to 53K and 15K, the F17 antiserum precipitated a 28K polypeptide and minor bands of 14K–16K, 18K–20K, and 11K–12K. Tryptic and chymotryptic maps of these polypeptides show that (1)14K–16K and 18K–20K polypeptides are members of the 53K/15K family, (2) 11K–12K polypeptides are related to each other but are unrelated to any other polypeptides, and (3) 28K is unrelated to any other polypeptides. We conclude that early region 1 codes for two (53K/15K family, 40K–50K family) or possibly more (e.g., 11K–12K family) families of polypeptides; the polypeptides included in each family overlap in amino acid sequence and therefore may be translated from overlapping spliced mRNAs. The possible contribution of these polypeptides to the phenotype of Ad2-transformed cells is discussed.