Synthesis in Escherichia coli of human adenovirus type 12 transforming proteins encoded by early region 1A 13S mRNA and 12S mRNA.

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Abstract
To further study the human adenovirus(Ad)-encoded early region 1A (E1A) tumor (T) antigen and to facilitate their purification, complementary DNA (cDNA) copies of the Ad12 E1A 13S mRNA and 12S mRNA were cloned downstream of a hybrid E. coli trp-lac (tac) promoter. Up to 8% of the protein synthesized in E. coli cells transformed by each of the 2 different Ad12 E1A cDNA constructs were immunoprecipitated as a MW 47,000 protein by antibody to a synthetic peptide encoded in the Ad12 E1A DNA sequence. Both proteins produced in E. coli appear to be authentic and complete Ad12 E1A T antigens because they possess the Ad12 E1A NH2-terminal amino acid sequence predicted from the DNA sequence; the Ad12 E1A COOH-terminal sequence, as shown by immunoprecipitation with anti-peptide antibody; an a MW and an acidic isoelectric point similar to that of the E1A T antigens synthesized in Ad12-infected and transformed mammalian cells. The T antigens were purifed to near homogeneity in yields of 100-200 .mu.g/g wet wt of transformed E. coli cells.