Identification and characterization of an immunologically conserved adenovirus early region 11,000 M_r protein and its association with the nuclear matrix

Antisera from some hamsters bearing adenovirus-induced tumors contain antibodies to an 11,000 M_r adenovirus-induced protein. In adenovirus-infected HeLa cells, this early viral protein was specifically associated with the nuclear matrix fraction. After two-dimensional gel electrophoresis, two forms of the 11,000 M_r protein at pI 5.6 and pI 5.4 were found. Only the pI 5.4 form of this protein was associated with the nuclear matrix fraction. Adenoviruses from groups A, B, C, D and E all produced an early viral protein (10,000 to 12,000 M_r) that reacted with group C antibody to the 11,000 M_r protein. To date, this is the only known early viral protein that is immunologically conserved in all of the human adenovirus groups. The positions of two methionine and seven leucine residues were determined by sequencing the first 35 amino acids from the N terminus of the adenovirus serotype 2 group C 11,000 M_r protein. The positions of these amino acid residues were compared to the adenovirus serotype 2 nucleotide sequence, which uniquely localized the structural gene of the 11,000 M_r protein to region E4, subregion 3 in type 2 adenovirus. A frameshift mutant, which contained a deletion of one base-pair in the structural gene of the 11,000 M_r protein, was isolated and mapped by marker rescue and nucleotide sequence analysis. This mutant failed to produce immunologically detectable 11,000 M_r protein. The mutant had a viable phenotype, producing normal levels of infectious virus in both HeLa cells and WI38 cells in culture. These experiments identify the first adenovirus early region 4 protein detected in virus-infected cells.