We have observed three effects of deletion mutations on polyadenylation of late SV40 mRNAs. The first class of mutants lack segments (-3 to -14 bp) between the 5′-AAUAAA-3′ and normal poly(A) site. These mutants produce mRNAs polyadenylated at new sites, downstream from the wild-type site. The poly(A) site is moved farther downstream as the deletions become larger; as a result, polyadenylation always occurs within an 11-19 nucleotide range from the AAUAAA sequence. The second class of mutants lack segments (-12 to -30 bp) between the AAUAAA sequence and the coding region of the mRNA. The poly(A) site for only one of these mutants was studied (dl 1457, -12 bp). In this case, the spatial relationship between AAUAAA and poly(A) site is altered, dl1457 produces a class of mRNAs polyadenylated at the first CA following the AAUAAA sequence, as well as other mRNAs poly-adenylated farther downstream. Finally, a 16 bp deletion that includes the AAUAAA sequence prevents poly(A) addition.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)