Specific ammonium ion requirement for functional ribosomal RNA tertiary structure.
In compactly folded RNAs, coordination or hydrogen bonding of cations in specific sites is a potentially important aspect of the tertiary structure. NH4+ specifically stabilizes the tertiary structure of a conserved, 58-nt fragment of the large subunit ribosomal RNA, as judged in two ways: a melting transition associated with tertiary interactions is sharpened and stabilized more effectively by NH4+ than by any alkali metal cation, and the affinity of the RNA fragment for ribosomal protein L11 or the antibiotic thiostrepton is approximately 10-fold stronger when measured in NH4+ than in Na+. The dependence of the melting temperature on NH4+ concentration shows that a single bound ion is responsible for these effects. The requirement of different ribosome functions for NH4+ suggests that other such sites exist in ribosomal RNAs.
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Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218.
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Draper
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D002414:Cations, Monovalent; D004926:Escherichia coli; D006860:Hydrogen Bonding; D008274:Magnesium / Q000737:chemistry; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012335:RNA, Ribosomal / Q000737:chemistry*; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry*; D013696:Temperature; D013883:Thiostrepton / Q000378:metabolism
D002414:Cations, Monovalent; D000644:Quaternary Ammonium Compounds; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D012269:Ribosomal Proteins; C027624:ribosomal protein L11; D013883:Thiostrepton; D008274:Magnesium