Transcription in vivo from SV40 early promoter deletion mutants without repression by large T antigen.

Transfection of monkey cells with recombinant plasmids containing a beta-globin coding region fused to wild-type or deleted simian virus 40 (SV40) early region promoters has allowed an analysis of the transcriptional activity of these promoters in the absence of repression by large T antigen. We find that deletion of the TATA sequence does not reduce the transcriptional effectiveness of the promoter; however, the 5' ends of the transcripts are heterogeneous rather than being restricted to the usual sites. The short GC-rich repeat sequences between nucleotides 37 and 107 and the tandemly repeated 72-bp segment between nucleotides 107 and 250 are each essential for promoter function. The GC-rich repeats are functionally redundant and probably interchangeable, since several subsets of two or three of the GC-rich segments are sufficient. One copy of the 72-bp sequence is sufficient to permit transcription. Moreover, the 72-bp repeat sequences function normally even if they are inverted relative to their normal orientation.