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Explore the significance of ribosomal RNA in translation processes, its biogenesis, structure, and implications in human diseases. Discover its crucial role in peptide bond formation and termination mechanisms.
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Ribosomal RNA Phillips Huang BMS 265
rRNA Nomenclature • Named based on sedimentation rates, measured in Svedberg units (S) • Larger sedimentation coefficients indicate faster sedimentation rates • Larger rRNAs sediment faster
rRNA Discovery • First discovered in the 1930s as part of the microsome by Albert Claude • Characterized as a ribosomal component in the 1950s by George Palade
Large Ribosomal Subunit • rRNA largely responsible for 3D structure • Peptidyl transferase center (PTC) composed of rRNA • A, P and E sites made up mainly of rRNA
Small Ribosomal Subunit • Atomic structure published in 2000 • Decoding center composed entirely of rRNA
rRNA Biogenesis in Eukaryotes • In prokaryotes, rRNAs are also synthesized as one primary transcript
Mechanism of action:Translation initiation in Prokaryotes • Translation initiation in eukaryotes involves binding of ribosomal components first to the mRNA 5’ cap
Mechanism of action:Translation elongation Residues of rRNA help to stabilize the mRNA:tRNA complex
Peptide Bond Formation • Involves nucleophilic attack of α-amino group of aminoacyl-tRNA on carbonyl carbon of peptidyl-tRNA Target carbonyl carbon is protected from hydrolysis prior to reaction Hypothesized transition state
rRNA as a Tool • Phylogenetic studies • rRNA sequences are highly conserved across species • In vitro translation systems • Used when overexpressed protein is toxic, rapidly degraded or insoluble in cells hagfish gnathostome lancelets lamprey
Role in Human Disease • Mutations in mitochondrial rRNA • Susceptibility to aminoglycoside-induced hearing loss • Changes to rRNA in cytoplasmic ribosomes • Defective pseudouridylation and X-linked Dyskeratosis Congenita (X-DC)