TRANSCRIPTIONAL ACTIVITY OF THE HUMAN IMMUNODEFICIENCY VIRUS-1 LTR PROMOTER IN FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

We have analyzed the transcriptional activity of the human immunodeficiency virus type I (HIV-1) LTR Promoter in the fission yeast Schizosaccharomyces pombe (S. pombe). The ability of a series Of 5'-deleted forms of the HIV-1 LTR Promoter to direct transcription of the chloramphenicol acetyltransferase reporter gene was studied. We found that the HIV-1 promoter is functional in S. pombe and that deletion of sequences upstream of the NF-kB binding site previously identified to contain the negative regulatory element (NRE) in mammalian cells, resulted in an about thirty-fold increase in transcriptional activity. Sequences in the HIV-1 promoter that bind NF-kB were found to be essential for transcriptional activation in S. pombe. In mammalian cells, transactivation of the HIV-1 LTR requires TAR sequences and the viral Tat protein. In fission yeast, Tat failed to transactivate the HIV-1 LTR, suggesting that S. pombe may lack a cellular factor(s) required for the Tat transactivation process.