TRANSCRIPTION Dr. Harinikumar. K.M. University of Agricultural sciences Bengaluru Karnataka. www.powerpointpresentationon.blogspot.com. The Central Dogma. The central dogma of molecular biology was first articulated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970
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TRANSCRIPTIONDr. Harinikumar. K.M.University of Agricultural sciences Bengaluru Karnataka
The central dogma of molecular biology was first articulated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970
The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. It states that such information cannot be transferred back from protein to either protein or nucleic acid.
In other words, the process of producing proteins is irreversible: a protein cannot be used to create DNA.
Prokaryotes : Relatively Simple….
Eukaryotes : Not so Simple….
FIGURE :Promoters and terminators define the unit
Initiation RNA pol I RNA pol III RNA pol II
ATP requirement no no yes
A and B or TATA box
core consensus sq. core element C box Inr
upstream element UCE GC box etc
general TFs SL1 TFIIIA B C various TFIIs
upstream factors UBF various up-
FIGURE : RNA polymerase has 4 types of subunit
RNA-pol of E. Coli
Rifampicin, a therapeutic drug for tuberculosis treatment, can bind specifically to the subunit of RNA-pol, and inhibit the RNA synthesis.
Site of DNA binding and RNA polymerization
FIGURE : Sigma factor controls specificity
Generally, bacteria that live in more varied environments have more sigma factors
Extreme heat shock, unfolded proteins
E. coli can choose between 7 sigma factors and about 350 transcription factors to fine tune its transcriptional output
FIGURE :- RNA polymerase surrounds the bubble
FIGURE RNA synthesis occurs in the transcription bubble
FIGURE :- RNA polymerase passes through several steps prior to elongation
FIGURE:- RNA polymerase changes size at initiation
FIGURE 14: DNA elements and RNA polymerase modules contributing to promoter recognition by sigma factor
TF for eukaryotic transcription
RNA polⅡ with transcription factors form transcription initiation complex. TF II D is the only factor which can recognize specific sites.
Pre initiation complex
CTD（Carboxyl Terminal Domain ) is repeated sequence of Tyr-Ser-Pro-Thr-Ser-Pro-Ser
CTD tail of RNA pol II is phosphorylated by TFⅡH
Pre-initiation complex (PIC)
Model of RNA PolII Preinitiation Complex
FIGURE :-Sigma and core enzyme must dissociate
FIGURE :- DNA turns at the active site
1. Rho-independent termination
FIGURE :- Rho terminates transcription
FIGURE :- Rho can terminate when a nonsense mutation removes ribosomes
FIGURE :- Transcription changes DNA structure
FIGURE :- Sigma controls promoter recognition
FIGURE :- E. coli has several sigma factors