title: Phosphorylation of ribosomal protein L18 is required for its folding and binding to 5S rRNA.
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.
authors.affiliation: Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Bloemink
authors.forename: P B
authors.initials: PB
authors.lastname: Moore
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D001411:Geobacillus stearothermophilus; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D012341:RNA, Ribosomal, 5S / Q000737:chemistry / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism*; D017186:Titrimetry
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012341:RNA, Ribosomal, 5S; D012269:Ribosomal Proteins; C029609:ribosomal protein L18; D010768:Phosphoserine