Fig. 1.

PEST region codon restriction suggests an interaction between the ORF and the 5′ UTR of the mRNA transcript. (A) The LLO PEST-like domain and nucleotides with 5′ complementarity. (B) Representative Western blot and quantification of LLO and P60 proteins from all synonymous S44S mutants. (C) Western blot quantification of LLO/P60 from additional PEST-encoding synonymous mutants in rich media. (D) RNAfold predicted mRNA structures and minimum free energies of WT hly and S44S (UCU263AGC). Red color indicates base-pair probabilities. Error bars represent SDs from three independent replicates. Significance is indicated as compared to WT and was determined by unpaired t test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001, ****P ≤ 0.0001, NS = not significant (P > 0.05). Unannotated statistical significance in C meant to indicate NS.