FIG. 5.

Effect of polyamines on the synthesis of RpoE-β-Gal fusion protein derived from mutated rpoE-lacZ mRNA in the 5′ untranslated region. (A) Possible secondary structure of the initiation region of rpoE mRNA was constructed by the method of Zuker (49). The positions in which the sequence was mutated are shown. (B) Effect of polyamines on RpoE-β-Gal fusion protein synthesis was tested by Western blot analysis using 10 μg of protein of cell lysate. The levels of rpoE-lacZ mRNA in cells cultured with or without 100 μg/ml putrescine were nearly equal, judging from dot blot analysis. (C) Immunoprecipitation of [³⁵S]methionine-labeled protein by antibody against β-Gal was performed as described in Materials and Methods. Values are means ± standard errors of triplicate determinations. Δ, removal of the nucleotide; +, addition of the nucleotide; →, the replacement of the nucleotide; ns, P > 0.05; *, P ≤ 0.05; **, P ≤ 0.01; PUT, putrescine.