RNA polymerase core enzyme structure and function
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1) The document discusses transcription in bacteria, including the components and subunits of RNA polymerase, the transcription cycle, and termination of transcription via rho helicase. 2) It also covers the three main types of RNA polymerase in cells (I, II, and III), their locations, and products. 3) Additionally, it mentions some key features of transcription initiation in eukaryotes, such as the TATA box, TATA-binding protein, and other transcription factors involved in the preinitiation complex.
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RNA polymerase core enzyme structure and function
- 5. RNA polymerase core enzyme is a multimeric protein a 2 ,b, b’, w The b’ subunit is involved in DNA binding The b subunit contains the polymerase active site
- 6. The a subunit acts as scaf fold on which the other subunits assemble. Also requires s-factor for initiation – forms holo enzyme complex
- 7. Site of DNA binding and RNA polymerization
- 10. Standard genes – s 70 Nitrogen regulated genes – s 54 Heat shock regulated genes – s 32
- 11. Closed complex Open complex Primer formation Disassociation of s-factor
- 13. 3’end tends to be AU rich easily to disrupt during pausing. Leads to disassembly of RNA polymerase complex
- 14. rho is an ATP-dependent helicase it moves along RNA transcript, finds the "bubble", unwinds it and releases RNA chain
- 17. type Location Products RNA polymerase I Nucleolus rRNA RNA polymerase II Nucleoplasm mRNA RNA polymerase III Nucleoplasm rRNA, tRNA, others Mitochondrial RNA polymerase Mitochondria Mitochondrial gene transcripts Chloroplast RNA polymerase Chloroplast Chloroplast gene transcripts
- 18. • RNA polymerase I, II, and III • All 3 are big, multimeric proteins (500-700 kD) • All have 2 large subunits with sequences similar to β and β' in E.coli RNA polymerase, so catalytic site may be conserved
- 20. Contain AT rich concensus sequence located –19 to –27 bp from transcription star t (TATA box) Site where RNA polymerase II binds
- 21. TFAIIA, TFAIIB – components of RNA polymerase II holo-enzyme complex TFIID – Initiation factor, contains TATA binding protein (TBP) subunit. TATA box recognition. TFIIF – (RAP30/74) decrease af finity to non-promoter DNA