Immortalization of T lymphocytes by human T-cell leukemia virus type 1 is independent of the Tax-CBP/p300 interaction

The human T-cell leukemia virus type I (HTLV-1) Tax oncoprotein is a 40-kDa nuclear phosphoprotein which functions in the viral replication cycle as a transcriptional trans-activator of the viral long terminal repeat. Tax int eracts with a variety of different transcription factors, including the CRE B binding protein (CBP)/p300 family of transcriptional accessory proteins. We demonstrate that a Tax mutant defective for the CBP/p300 interaction ret ains the capacity to immortalize primary human T lymphocytes when it is exp ressed from a functional molecular clone of HTLV-1. Thus, immortalization o f HTLV-1-infected cells appears to be independent of Tax-induced alteration s in CBP/p300 function.