Transcript Lecture 14 Student Powerpoint

Lecture12 Based on Chapter 18 Regulation of Gene
Expression in Eukaryotes I
Copyright © 2010 Pearson Education Inc.
1 -Levels of Control of Gene Expression in
Eukaryotes
Previously we discussed aspects of
transcription that involved the
production of a primary transcript and
the processing of this into aspects of
how this is processed into an mRNA
in Eukaryotes. This lecture focuses
on these topics and on how signals
are perceived that modulate the
expression of eukaryotic genes. The
next lecture will examine the details
of controlling gene expression posttranscriptionally.
2 - Control of Transcription Initiation by
Regulatory Proteins
1. In eukaryotes, control of gene expression is at the level
of transcription initiation
2. Controlled by promoter (immediately upstream) and
enhancers (distal from the gene).
a.Expression from the promoter alone is at basal level.
b.For maximal transcription, activator proteins bind to:
i. Promoter-proximal elements
ii. Enhancer elements
3. Binding of activators:
a.Recruits proteins that make the chromatin accessible to the
transcription machinery.
b.Increases binding of the transcription machinery to the promoter.
4. Repressors are also used to decrease or prevent
transcription.
3 – Regulation of Transcription Initiation by
Activators
4 - Regulation of Transcription Initiation by
Activators II
5 – Inhibiting transcription Initiation by
Repressors
1. Repressors inhibit activation of transcription by
activators.
a. Two domains occur in repressors, a DNA-binding
region and a repressing domain.
b. Repressors work in a variety of ways. Examples:
i. Repressor binds near activator’s binding site, and repressor
domain interacts with activation domain of the activator,
preventing activation.
ii. Repressor binding site overlaps activator binding site,
preventing activator binding.
iii. Chromatin remodeling can also block transcription if
repressor binds its site and recruits HDAC (histone
deacetylase) to cause chromatin compaction.
10 - Combinatorial Gene Regulation: The
Control of Transcription by Combinations of
Activators and Repressors
6 - Case Study: Positive and Negative
Regulation of Transcription of the Yeast
Galactose Utilization Genes
7 - Case Study: Regulation of Transcription in
Animals by Steroid Hormones I
8 - Case Study: Regulation of Transcription in
Animals by Steroid Hormones II
9 - Case Study: Regulation of Transcription in
Animals by Steroid Hormones III
7 – Case Study: Peptide Hormone Receptors
Case Study: Insulin Signaling Pathway
1 -Levels of Control of Gene Expression in
Eukaryotes
12 – Gene Silencing and Genomic Imprinting
13 – Gene Silencing by DNA Methylation
14 – Genomic Imprinting
1 -Levels of Control of Gene Expression in
Eukaryotes