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Messenger RNA Todd Metzger BMS 265 May 8, 2009. Nomenclature Messenger RNAs (mRNA) describes cytoplasmic product Pre-mRNA (part of hnRNA) in nucleus is.

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Presentation on theme: "Messenger RNA Todd Metzger BMS 265 May 8, 2009. Nomenclature Messenger RNAs (mRNA) describes cytoplasmic product Pre-mRNA (part of hnRNA) in nucleus is."— Presentation transcript:

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 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 Messenger RNA Visualized Miller 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 Catalytic core Yeast RNA pol II 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

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13 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

14 mRNA Secondary Structure - No significant differences for human sequences

15 mRNA Vaccinations - Direct Hess et al 2006

16 mRNA Vaccinations - Indirect Hess et al 2006

17


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