Mutational dissection of the 21 bp repeat region of the SV40 early promoter reveals that it contains overlapping elements of the early-early and late-early promoters.
Using quantitative S1 nuclease analysis and recombinants which contain the SV40 early promoter region linked to the rabbit beta-globin gene coding sequence, we have studied the effect of deletion, inversion and point mutations, located within the 21 bp repeat region, on initiation of transcription from the early-early and late-early startsites in the absence of T-antigen. Our data establish unequivocally that the six GC-rich repeats present in the 21 bp repeat region are essential elements of both the early-early and late-early promoters and that they are not redundant, since mutations, which affect only the GC-rich repeat most proximal to the TATA box, decrease drastically the activity of the early-early promoter, but increase that of the late-early promoter. On the other hand, the four GC-rich repeats most proximal to the 72 bp repeat are common elements of the two overlapping early-early and late-early promoters. Our results, which confirm that the early-early promoter is stronger than the late-early one, also support our previous suggestion that they are in competition for the transcriptional machinery. The general organization of the SV40 early promoter region is discussed.
D001482:Base Composition; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant / Q000378:metabolism; D004720:Endonucleases; D009154:Mutation; D009876:Operon; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D013539:Simian virus 40 / Q000235:genetics*; D015719:Single-Strand Specific DNA and RNA Endonucleases; D014158:Transcription, Genetic
D004274:DNA, Recombinant; D004720:Endonucleases; D004262:DNA Restriction Enzymes; D015719:Single-Strand Specific DNA and RNA Endonucleases