MAPPING OF TRANSCRIPTIONAL REGULATORY DOMAINS OF PSEUDORABIES VIRUS IMMEDIATE-EARLY PROTEIN

The 180 kilodalton immediate-early protein (IE180) of pseudorabies vir us functions as a strong transactivator of several different promoters and also as a repressor of its own transcription. To map the function al domains of IE180, we prepared various truncated mutants and analyze d their transcriptional regulatory activities using the chloramphenico l acetyl transferase (CAT) assay. Analysis of mutants truncated from t he carboxy-terminal end of the 1460-amino acid polypeptide showed that a polypeptide possessing amino acids 1 to 1081 retained significant f unctions of transactivation and autoregulation potential. On the other hand, removing amino acids 1 to 131 resulted in a complete loss of tr ansactivation potential, indicating that the domain responsible for tr ansactivation is located in the amino-terminal end of IE180. Additiona l amino-terminal truncation up to amino acid 453 did not affect the au toregulation activity, indicating that the region between amino acids 454 and 1081 has autoregulation potential.