1. Chapter 21 (part 1) Transcription

2. Central Dogma

3. RNA Content of E. coli Cells type Steady State Levels Synthetic Capacity Stability rRNA83%58%High tRNA14%10%High mRNA3%32%Very Low

4. E. Coli RNA Polymerase RNA polymerase core enzyme is a multimeric protein    ’  The  ’ subunit is involved in DNA binding The  subunit contains the polymerase active site The  subunit acts as scaffold on which the other subunits assemble. Also requires  -factor for initiation –forms holo enzyme complex Site of DNA binding and RNA polymerization

5. General Gene Structure 5’3’ Transcribed regionterminator Promoter

6. Gene Promoters

7. Other  -Factors Standard genes –  70 Nitrogen regulated genes –  54 Heat shock regulated genes –  32

8. Transcriptional Initiation Closed complex Open complex Primer formation Disassociation of  -factor

10. Pausing induces termination 3’end tends to be AU rich easily to disrupt during pausing. Leads to disassembly of RNA polymerase complex

11. Rho Dependent Termination rho is an ATP- dependent helicase it moves along RNA transcript, finds the "bubble", unwinds it and releases RNA chain

13. Eukaryotic RNA Polymerases typeLocationProducts RNA polymerase INucleolusrRNA RNA polymerase II NucleoplasmmRNA RNA polymerase III Nucleoplasm rRNA, tRNA, others Mitochondrial RNA polymerase Mitochondria Mitochondrial gene transcripts Chloroplast RNA polymerase Chloroplast Chloroplast gene transcripts

14. Eukaryotic RNA Polymerases RNA polymerase I, II, and III All 3 are big, multimeric proteins (500-700 kD) All have 2 large subunits with sequences similar to  and  ' in E.coli RNA polymerase, so catalytic site may be conserved

15. Eukaryotic Gene Promoters Contain AT rich concensus sequence located –19 to –27 bp from transcription start (TATA box) Site where RNA polymerase II binds

16. Transcription Factors 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 affinity to non- promoter DNA