title: Dynamic structure of bacterial ribosomal 5S RNA helices II and III of B. megaterium 5S RNA.
abstract: A possible switch between two conformations, previously observed in an enzymatically cleaved fragment of E. coli 5S ribosomal RNA (a Gram-negative bacterium) containing helices II and III, has been examined by means of proton nuclear magnetic resonance spectroscopy (10-15 ppm) as a function of [Mg2+] and temperature for an RNase-T1 digested fragment of Bacillus megaterium 5S rRNA (a Gram-positive bacterium) containing the same helices II and III. The conformational changes induced in the fragment are not accompanied by breakage of some base-pairs and formation of others, but rather consist simply of tightening or loosening of helices with retention of existing base-pairs. Helix III is found to be more flexible than helix II. Finally, the loop conformation is conserved over a wide range of Mg2+ concentration, suggesting that the loop may serve an important role in the biological function of 5S rRNA in ribosomes.
authors.affiliation: Department of Chemistry, Ohio State University, Columbus 43210.
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: A G
authors.initials: AG
authors.lastname: Marshall
mesh_terms: D001410:Bacillus megaterium / Q000648:ultrastructure*; D001483:Base Sequence; D006860:Hydrogen Bonding; D008274:Magnesium; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009038:Motion; D009690:Nucleic Acid Conformation; D012335:RNA, Ribosomal / Q000648:ultrastructure*; D012341:RNA, Ribosomal, 5S / Q000648:ultrastructure*; D012270:Ribosomes / Q000648:ultrastructure*; D013696:Temperature
chemical_list: D012335:RNA, Ribosomal; D012341:RNA, Ribosomal, 5S; D008274:Magnesium