Helix 69 of 23 S rRNA is a region of considerable interest. It is located at the interface of the two ribosomal subunits. Helix 69 is believed to be a dynamic region of the ribosome, participating in RNA-RNA with helix 44 of the small subunit and tRNA and RNA-protein interactions. Helix 69 in Escherichia coli contains three modifications, two pseudouridines (Ψ) and 3-methylpseudouridine (m3Ψ). My research goal is to understand the structure and dynamics of helix 69 and investigate the contribution of pseudouridine towards stability, structure and dynamics in this region. Circular dichroism spectroscopic studies, nuclear magnetic resonance spectroscopic studies, and thermal melting experiments of helix 69 RNA were used to identify structural and stability changes in helix 69. Spectroscopic and thermodynamic experiments have revealed a pH-dependent structural change in helix 69 and cooperative structural and stability effects between pseudouridines of helix 69, which may assist in propagation of structural perturbations to the loop region in helix 69. Supported by NIH GM054632.
Figure 1: A) Cryo-electron microscopic image of the ribosome is shown. Location of helix 69 is shown by an arrow.(1) B) The secondary structure of helix 69 is shown. C,D) The chemical structure of pseudouridine and uridine are shown.
1.Yusupov, M.M., Yusupova, G.Z., Baucom, A., Lieberman, K., Earnest, T. N., Cate, J.H.D., Noller, H.F. 2001. Crystal Structure of the Ribosome at 5.5 Å Resolution. Science. 292: 883-896.
