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Messenger RNA

Messenger RNA. Todd Metzger BMS 265 May 8, 2009. Nomenclature. Messenger RNAs (mRNA) describes cytoplasmic product Pre-mRNA (part of hnRNA) in nucleus is processed and exported Describe by gene/protein, including isoform or NCBI sequence (NM, natural; XM, in silico)

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Messenger RNA

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  1. Messenger RNA Todd Metzger BMS 265 May 8, 2009

  2. Nomenclature • Messenger RNAs (mRNA) describes cytoplasmic product • Pre-mRNA (part of hnRNA) in nucleus is processed and exported • Describe by gene/protein, including isoform • or NCBI sequence (NM, natural; XM, in silico) • New methods for describing spliced mRNAs (Sammeth 2008)

  3. 1955 - Goldstein and Plaut 6 min 62 hr

  4. Discovery • Volkin and Astrachan discovered a new type of RNA synthesized following infection of bacteria by T2 Bacteriophage (Volkin 1956) • Newly synthesized RNA mirrored composition of T2 DNA • Brenner, Jacob, and Meselson found that only RNA, and not ribosomes, were newly synthesized following infection (1961) • The term messenger RNA was coined

  5. Translation Leads to Linear Protein Synthesis • Dintzis 1961 • Reticulocytes analyzed • Make ~90% hemoglobin • Radiolabeled amino acids incorporated to C-terminus only

  6. 1970 - Messenger RNA VisualizedMiller et al

  7. Biogenesis • Enzymatic Reaction by RNA Polymerase • RNA Pol II in eukaryotes • Involves Initiation Factors (TFIIB,D,E,F,H) and Mediator Complex • Core RNA polymerase II is 12 subunits, 500 kDA, highly conserved • 10 subunit catalytic core Woychik 2002, Sims III 2004

  8. Yeast RNA pol II Catalytic core Positively charged cleft Active site occurs between the wall and clamp (shown closed - elongation)

  9. Transcription • Template DNA, 5 GTFs, and RNA pol II associated to form pre-initiation complex • TFIID contains the TATA-box binding protein (TBP) • TFIIE and -H melt DNA • CTD phosphorylation is required for dissociation of initiation factors and entrance to the elongation phase • TFIIS allows stalled transcription to continue • Reverse procession followed by cleaved of RNA

  10. TFIIS

  11. Mediator • Connects transcription factors to basal machinery Casamassimi 2007

  12. mRNA Secondary Structure • Many mRNAs can code for the same protein • Made program to scramble codons while preserving base content • Looked at 50 bp structures Katz 2003

  13. mRNA Secondary Structure - No significant differences for human sequences

  14. mRNA Vaccinations - Direct Hess et al 2006

  15. mRNA Vaccinations - Indirect Hess et al 2006

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