Sequences controlling in vitro transcription of SV40 promoters

A series of deletion mutants of SV40 were tested for early and late promoter activity in vitro in a transcription extract prepared from HeLa cells. These mutants had previously been characterized for expression in vivo. Transcription in vitro from both the SV40 early and late promoters was strongly dependent on an upstream region of DNA that contains six direct GC repeats. Sequences spanning two or more of these repeats stimulated transcription in a bidirectional fashion, at distances of 50-200 bp. These sequences may function by mediating the activity of a specific transcriptional factor. Little effect on transcription in vitro was observed upon deletion of the 72-bp enhancer elements. With this exception, the sequence dependence of early and late transcription in vitro was similar to that observed previously in vivo, both of the region including the GC repeats and of the early TATA sequence.