title: Structure modulation of helix 69 from Escherichia coli 23S ribosomal RNA by pseudouridylations.
abstract: Helix 69 (H69) is a 19-nt stem-loop region from the large subunit ribosomal RNA. Three pseudouridine (Ψ) modifications clustered in H69 are conserved across phylogeny and known to affect ribosome function. To explore the effects of Ψ on the conformations of Escherichia coli H69 in solution, nuclear magnetic resonance spectroscopy was used to reveal the structural differences between H69 with (ΨΨΨ) and without (UUU) Ψ modifications. Comparison of the two structures shows that H69 ΨΨΨ has the following unique features: (i) the loop region is closed by a Watson-Crick base pair between Ψ1911 and A1919, which is potentially reinforced by interactions involving Ψ1911N1H and (ii) Ψ modifications at loop residues 1915 and 1917 promote base stacking from Ψ1915 to A1918. In contrast, the H69 UUU loop region, which lacks Ψ modifications, is less organized. Structure modulation by Ψ leads to alteration in conformational behavior of the 5' half of the H69 loop region, observed as broadening of C1914 non-exchangeable base proton resonances in the H69 ΨΨΨ nuclear magnetic resonance spectra, and plays an important biological role in establishing the ribosomal intersubunit bridge B2a and mediating translational fidelity.
authors.affiliation: Department of Chemistry, Wayne State University, Detroit, MI 48202, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Jiang
authors.forename: Raviprasad
authors.initials: R
authors.lastname: Aduri
authors.forename: Christine S
authors.initials: CS
authors.lastname: Chow
authors.forename: John
authors.initials: J
authors.lastname: SantaLucia
mesh_terms: D020029:Base Pairing; D004926:Escherichia coli / Q000235:genetics*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011560:Pseudouridine / Q000737:chemistry* / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012338:RNA, Ribosomal, 23S; D011560:Pseudouridine