Phosphorylation of ribosomal protein L18 is required for its folding and binding to 5S rRNA. |
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Authors: | M J Bloemink P B Moore |
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Affiliation: | Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA. |
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Abstract: | Ribosomal protein L18 from Bacillus stearothermophilus (bL18) includes a previously unreported phosphoserine residue. The folded conformation of the protein is stabilized by the dianionic form of the phosphate group of that residue. In the absence of Mg2+, the pK(a) of the phosphate group is so high that the protein is not fully folded at pH 7. In the presence of Mg2+, its pK(a) drops significantly, and consequently the native conformation of bL18 becomes stable at pH 7 and the protein is able to bind to 5S rRNA. Dephosphorylated bL18 does not bind to 5S rRNA at neutral pH. |
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