The functional and structural specificity of SAM–RNA binding. (A) The positions and identities of the mutations on the RNA. (B) The β-gal activity of the 5′UTR RNA mutations in the presence of 200 mg/L methionine. Mutant RNA repression is expressed as a proportion of wild-type RNA repression. The positions of the potential functional sites in the RNA are indicated. (C) β-galactosidase expression data of the wild-type UTR and M1–M8 point mutant RNAs in S. pombe cells. Cells were grown in EMM media in the absence of thiamine with or without 200 mg/L methionine. Error bars are standard deviations of at least three independent experiments. (D) β-galactosidase expression data of the wild-type UTR and M9–M14 mutant RNAs in S. pombe cells. Cells were grown in EMM media in the absence of thiamine with or without 200 mg/L methionine. Error bars are standard deviations of at least three independent experiments. (E) Electropherogram of OsO4 modification of the 5′ UTR of the sam1 RNA (nucleotides 128–161), comparing the reactivity of the mutation M2 (U139A) (the blue trace) with wild-type RNA (red trace).
