THE HERPES-SIMPLEX VIRUS-1 GENE ENCODING A PROTEASE ALSO CONTAINS WITHIN ITS CODING DOMAIN THE GENE ENCODING THE MORE ABUNDANT SUBSTRATE

The herpes simplex virus 1 open reading frames U(L)26 and U(L)26.5 are 3' coterminal. The larger, U(L)26 open reading frame encodes a protein approximately 80,000 in apparent molecular weight and contains the promoter and coding sequence of the U(L)26.5 gene, which specifies a capsid protein designated infected cell protein 35. The larger product contains in its entirely the amino acid sequence of the smaller protein. We report that the U(L)26 gene encodes a protease which catalyzes its own cleavage and that of the more abundant product of U(L)26.5. By inserting the coding sequence of an epitope to a cytomegalovirus monoclonal antibody and homologs of the immunoglobulin G binding domain of staphylococcal protein A into the 3' termini of the coding domains of the two open reading frames, we identified both products of the cleavage and determined that the cleavage site is approximately 20 amino acids from the carboxyl termini of both proteins.