Identification of a promoter component involved in positioning the 5' termini of simian virus 40 early mRNAs.

Abstract

The 5'' termini of the principal early mRNA produced in [human SV-80 and rat fibroblast] cells transformed by wild-type SV-40 lie 21-25 nucleotides downstream from an A-T-T-T-A-T sequence on the DNA template. The 5'' termini of early mRNA produced by 5 origin-defective mutants containing deletions downstream from the A-T-T-T-A-T sequence and 1 viable mutant dl892 with a deletion starting 15 nucleotides upstream from this sequence were determined by a method involving synthesis, separation and determination of the sequences of DNA complementary to 5'' termini. Mutant dl892 produced early mRNA with the same principal 5'' termini as wild-type virus; the origin-defective mutants produced mRNA with principal 5'' termini shifted downstream by a distance equivalent to the length of the deleted DNA segment. A DNA sequence of 29 nucleotides, which includes the A-T-T-T-A-T sequence, apparently contains a component(s) of a promoter for early transcription. This component functions in positioning the 5'' ends of the principal early mRNA 21-25 nucleotides downstream from the A-T-T-T-A-T sequence and acts independently of the downstream sequences.