KelleyLect2_2009 - RNA: structurally and functionally...

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Unformatted text preview: RNA: structurally and functionally diverse RNA: Amino acid transport Ribosomal function Translational regulation Intron splicing 3D tRNA structure 3D 3D tRNA structure Types of interactions Watson-Crick base pairs Non-Watson-Crick base pairs Triple base pairs Metal ion/polyamine binding tRNAPhe structure tRNA First nucleic acid to be structurally characterized: Alex Rich (MIT, 1974) Triple base pairs in tRNAPhe U12:A23 - A9 I I I Triple base pairs in tRNAPhe U12:A23 - A9 Stabilizes L-shaped fold I I I Triple base pairs in tRNAPhe C13:G22 - G46 CH3 group prevents H-bonds with N7 I I I Triple base pairs in tRNAPhe Triple C13:G22 - G46 I Stabilizes interface between variable loop and D-stem I I Non-Watson-Crick base pairs in tRNA Phe G18:U55 I I Non-Watson-Crick base pairs in tRNA Phe Brings T and D loops together G18:U55 I I Non-Watson-Crick base pairs in tRNA Phe G4:U69 I Exposed NH2 group is a good recognition handle for proteins I Non-Watson-Crick base pairs in tRNA Phe Non-Watson-Crick G4:U69 I I Divalent metals stabilize tRNA structure Metal ion/RNA interactions Mg2+/phosphate Mg2+/H20/base Mg2+/H20/2’-OH Polyamines stabilize tRNA structure Polyamines 3D tRNA structure 3D Types of interactions Watson-Crick base pairs Non-Watson-Crick base pairs Triple base pairs Metal ion/polyamine binding RNA: structurally and functionally diverse RNA: Amino acid transport Ribosomal function Translational regulation Intron splicing The ribosome’s core is composed of RNA with highly folded and complex structure structure Nucleic acids structure Part II summary - RNA structure is complex and variable - Helical sections resemble DNA - Tertiary structure stabilized by non-Watson Crick base pairing and other interactions - The folded structures of large RNAs (e.g. ribosomal RNAs) constitute the cores of important biological machinery ...
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