Chapter 3

The Transfer of Genetic Information

---- From---- From totoDNADNA RNARNA

3.1 Overview

1. Procedures of Gene Expression

(1) Gene expression

(2) Steps

①

②

③

④

5’------ATTGCCTGAATGGTCCC----3’

5’------TAACGGACTTACCAGGG----3’

5’------AUUGCCUGAAUGGUCCC----3’

5’------UAACGGACUUACCAGGG----3’

coding strand, non-template strand, sense strand, plus strand……(+)

template strand, antisense strand, minus strand……(─)

sense RNA

antisense RNA

2. Coding Strand and Antisense Strand

3. Steps are required for the transcription:

(1) Initiation

(2) Elongation

(3) Termination

4. Main Components for Transcription

substrate

template

RNA polymerase 5’ → 3’

Core enzyme(α2ββ ω)

holoenzyme(α2ββ ω )

RNA pol in prokaryotes

RNA polymerases in Eukaryotes

3.2 Transcription in Prokaryotes

1. DNA Elements for Initiation of Transcription in Prokaryotes

(1) Promoter

(2) Structure of Promoter

-35 region, -10 region, INR (Inr)

2. Initiation of Transcription in Prokaryotes

3. Elongation and Termination of Transcription in Prokaryotes

ρ-independent termination (strong)

ρ-dependent termination (weak)

3.3 Transcription in Eukaryotes

1. DNA Elements for Initiation of Transcription in Eukaryotes

Cis-acting elements

TATA box, UPE, UAS…..

Trans-acting factor

TFs

2. Initiation of Transcription in Eukaryotes

PIC of RNA pol II t

ranscription

upstream control eleme

nt (UCE). 

upstream binding factors (UBF)

PIC of RNA pol I tr

anscription

upstream control eleme

nt (UCE). 

upstream binding factors (UBF)

PIC of RNA pol III tr

anscription

TFIIB-related factor, BRF

PIC of 5S rRNA trans

cription

Animation

1. Coding RNA and Non-coding RNA

Coding RNA - mRNA

Non-coding RNA (ncRNA) - any RNA

that is not translated into a protein.

3.4 RNA Processing

2. Types of RNA Processing

End modification

Splicing

Cutting events

Chemical modification

3. End-modification of pre-mRNA

5’-cap

3’-Poly(A) : Polyadenylate polymerase

4. RNA Splicing

pre-mRNA splicing tRNA-splicing Group I intron splicing Group II intron splicing

pre-mRNA

The mechanism of pre-mRNA splicing

snRNPs

spliceosome

U1snRNPs is released.

U4snRNPs is released.

Two transesterification reactions

Animation

tRNA splicing

Group I intron splicing

Group II intron splicing

Alternative Splicing

Cis SplicingTrans Splicing

mRNA Editing of Human Apolipoprotein - B

5. RNA Editing

3.5 Reverse transcription

What is a Ribozyme?

Sidney Altman

Th omas Cech

1989 Nobel Prize In Chemistry

3.6 Ribozymes

Mechanism of Ribozyme

- the hammerhead ribozyme (plant virus)

- the hairpin ribozyme (plan virus)

- hepatitis delta ribozyme (human virus)

- group I and group II intron ribozyme

- RNAse P (tRNA maturation)

Types of Ribozyme

Natural ribozymes:Peptidyl transferase 23S rRNA

RNase P

Group I and Group II introns

Leadzyme

Hairpin ribozyme

Hammerhead ribozyme HDV ribozyme Mammalian CPEB3 ribozyme VS ribozyme glmS ribozyme CoTC ribozyme

RNA World Hypothesis

What is the origin of life?

DNA?

RNA?

Summary

1. Regulatory elements of prokaryotes and eukaryotes

for RNA transcription

2. RNA polymerase of prokaryotes and eukaryotes

3. Procedures of RNA transcription

4. mRNA structure of prokaryotes and eukaryotes

5. Types of RNA processing

6. Types of RNA splicing and their mechanisms

7. RNA editing mechanism

8. Mechanism of reverse transcription

9. Ribozyme and silencing mechanism