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Презентация на тему Gene Expression Systems in Prokaryotes and Eukaryotes

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Gene Expression Systems in Prokaryotes and EukaryotesExpression studies: 1. Analyzing Transcription - Northern blot - Micro array - real-time PCR - Primer extension
Gene Expression Systems in Prokaryotes and EukaryotesExpression studiesExpression in Prokaryotes (Bacteria)Expression in Eukaryotes Gene Expression Systems in Prokaryotes and EukaryotesExpression studies: 1. Analyzing Transcription Studying Transcription Microarray technique – DNA chips Studying Transcription Primer Extension Promoter StudiesUsed reporter genes: Lac Z GFP LuciferasePromoter Promoter studies by using reporter genes Luciferase (luc) systemsfirefly species Photinus pyralis oxidation of compounds called luciferans( ATP-dependent Green fluorescent protein (GFP)autofluorescent protein from Pacific Northwest jellyfish Aequorea victoriaultraviolet light GFP expression is harmless for cells and animals GFP transgenic mice from Engineered proteins are covering all the spectrumSan Diego beach scene drawn with Use of green fluorescent protein (GFP) as a reporter gene.Page 119 Analyzing Translation – Western Blot 2 D Electrophoresis Gene ExpressionTranscriptional startTranslational start Gene ExpressionGene copy number:  1. Plasmid copy number:  The copy-number Incompatibility of plasmids:Not all plasmids are able to coexist in the same Homologous integration into chromosomeInsertion on Bacillus subtilis chromosome Protein expression in prokaryotic systemswww.qiagen.comSo, this new story would be about vectors General advices for one who wants  to produce gene expression www.wzw.tum.dewww.wzw.tum.de/gene-quantification/ www.wzw.tum.de/gene-quantification/ mrna.html IntronsNot an issuewhen you clone a cDNA Orientation of insert  (could go backward, if cloned with same-type sticky Fusion proteins.When expressing a fusion proteins, ensure that both of them arein PostTranslational modification Eukaryotic cells have Golgi system Prokaryotic cells do not have itnucleusGolgi Efficiency of expression in E.coliDependent of: 1. Type of transcription promoter and Factors affecting transcription Promoters (including regulated ones)PROKARYOTIC!!!! 2. TerminatorsPROKARYOTIC!!!! Variations between prokaryotic promoters are minimalhttp://www.blc.arizona.edu/marty/411 Factors affecting translation1. Ribosome binding site (RBS)2. Codon bias3. Stability of the transcript Ribosome binding site (RBS) =  translation initiation site  complimentary to 16S rRNA Codon Usage in E. coli & humans Codon Optimization StrategiesChemically synthesize new geneAlter sequence of the gene of interest Commercial E. coli strains  encode for a number of the rare codon genes Mitochondria and chloroplast genes Alterations in the Standard Genetic Code in Mitochondria Factors affecting protein stability Overall level of protease activity in bacterial cells Protease-deficient host strains BL21, the work horse of E. coli expression, is Inducible bacterial promotersWhy not to use constitutive, always strong promoter? Induction Because BL(DE3) inducible system and pET vectors (invented in 1984 by Bill Studier, Why repressor gene and gene of interest are expressed from different DNA Where your expressed protein will be located? Inclusion bodies(insoluble) Cytoplasm (soluble)Periplasmatic space(soluble 1. Inclusion bodies  (most common case) -- Inclusion bodies are formed Electron micrograph of an inclusion body of the protein prochymosin in an Good side of inclusion bodiesinclusion bodies can be accumulated in the cytoplasm SDS-PAGE analysis of recombinant protein produced as inclusion body hG-CSF mbel.kaist.ac.krmbel.kaist.ac.kr/research/ protein_en1.html Recovery of proteins from inclusion bodiesIs not a straightforward process, but road Question of questions –  how to purify your protein? Diversity of proteins could be exploited Column chromatographyMatrix particles usually packed in Column chromatographyDifferent proteins are retarded to different extents by their interaction with (A) ION-EXCHANGE CHROMATOGRAPHYIon-exchange columns are packed with small beads that carry positive (B) GEL-FILTRATION CHROMATOGRAPHYGel-filtration columns separate proteins according to their size on tiny (C) AFFINITY CHROMATOGRAPHYAffinity columns contain a matrixcovalently coupled to a molecule that Protein  electrophoresis Essential Cell Biology: An Introduction to the Molecular Biology of the Cell www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm Fusion proteinsincrease production levelfacilitate purification (taq)detection of expression (GFP fusion)Redirection of proteins Most widely used purification strategy – to produce your protein as a Histidine: a charged aminoacid The affinity of this interaction is very high GST – fusion. Principle is the same. Binds to glutation Require strong binding to glutathione Require strong binding to glutathione GSTs function GlutathioneGST from Schistosoma japonicum 1) Keeps fusion proteins soluble2) Used for fusion FUSION PROTEIN BOUND TO GLUTATHIONE SEPHAROSEGlutathioneGSTFOREIGN PEPTIDESEPHAROSEPurification is simple : -- WASH Some problems of production in E. coli Some E.coli expression host considerations Principal factors in bacterial expression Type of expression vectors Initiation of Transcription   Promoters for Expression in ProkaryotesIn Escherichia coli The Lac promoter System The trp promoter system E. coli Promoter Sites Synthetic E. coli promoters-35-10ptac -> -35 box from ptrp + -10 box from plac -> pt+ac Inverted Promoter System (from Salmonella) -> for very toxic proteins BacillusIn 1872, Ferdinand Cohn, a student of Robert Koch, recognized and named BacillusAntibiotic Producers: B. brevis (e.g. gramicidin, tyrothricin), B. cereus (e.g. cerexin, zwittermicin), BacillusBacillus strains used as production organisms: Bacillus as expression host Bacillus as expression host Products produced in Prokaryotic Systems Restriction Endonucleases -> produced in E. coliL- Expression in Eukaryotic SystemsYeast  - Saccharomyces cerevisiae (baker’s yeast)  - Expression in YeastAutonomous replicating vectors -> shuttle vectors Expression in Saccharomyces cerevisiae Autonomous replicating systems Expression in Saccharomyces cerevisiae Integrative systemsProbability for integration higher with linear fragments ! Expression in Saccharomyces cerevisiae Expression in Saccharomyces cerevisiae Yeast are efficient secretors !Secretory expression preferred if:-> if product toxic-> if Expression in S. cerevisiae – Pichia pastorisProblems with production in S. cerevisiae:For Expression in Pichia pastoris Integrative systems Expression in Pichia pastoris Expression in Pichia pastoris Expression in Insect cellsBaculovirus:-> infects invertebrates (insects)-> in infection cycle 2 forms Expression in Insect cellsBaculovirus:-> Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) many Baculovirus expression system Why this system?Insect cells have almost the same posttranslational modifications as mammalian Mammalian cell expression system1. Why do we use that system?  -> Mammalian cell expression system  Gene expression in mammalian cell linesA convenient alternative for setting up mammalian Competitiveness  of different expression systems http://www.proteinsciences.com/technology/pix/best_worse.gif
Слайды презентации

Слайд 2 Gene Expression Systems in Prokaryotes and Eukaryotes
Expression studies:

Gene Expression Systems in Prokaryotes and EukaryotesExpression studies: 1. Analyzing Transcription

1. Analyzing Transcription
- Northern

blot
- Micro array
- real-time PCR
- Primer extension

2. In vivo Expresion studies
Use of report genes to study regulatory elements

3. Analyzing Translation
- Western blot - immuno assays
- 2D electrophoresis
- proteomics

Слайд 3 Studying Transcription
Microarray technique – DNA chips

Studying Transcription Microarray technique – DNA chips

Слайд 5 Studying Transcription
Primer Extension

Studying Transcription Primer Extension

Слайд 6 Promoter Studies
Used reporter genes:

Lac Z
GFP

Promoter StudiesUsed reporter genes: Lac Z GFP LuciferasePromoter

Luciferase
Promoter


Слайд 7 Promoter studies by using reporter genes

Promoter studies by using reporter genes

Слайд 8 Luciferase (luc) systems
firefly species Photinus pyralis
oxidation of

Luciferase (luc) systemsfirefly species Photinus pyralis oxidation of compounds called luciferans(

compounds called luciferans
( ATP-dependent process)
luciferans emit fluorescense
Expressed luciferase catalyses


mouse

with a strain of salmonella

Mice are injected
with LUC+ salmonellas.
Sensitive digital cameras
allow non-invasive detection.
For GT vectors
pics look the same

luminometer measurement



Слайд 9 Green fluorescent protein (GFP)
autofluorescent protein from Pacific Northwest

Green fluorescent protein (GFP)autofluorescent protein from Pacific Northwest jellyfish Aequorea victoriaultraviolet

jellyfish
Aequorea victoria



ultraviolet light causes GFP
to autofluoresce
In

a bright green color




Jellyfish do nothing with UV,
The activate GFP by aequorin
(Ca++ activated,
biolumuniscent helper)


Слайд 10 GFP expression is harmless for cells and animals
GFP

GFP expression is harmless for cells and animals GFP transgenic mice

transgenic mice from
Osaka University
(Masaru Okabe)
GFP construct could

be used for construct tracking in living organism

GFP labelled image of a human tumor.
Vessel on the tumor surface
are visible in black


Слайд 11
Engineered proteins
are covering
all the spectrum
San Diego

Engineered proteins are covering all the spectrumSan Diego beach scene drawn

beach scene
drawn with living bacteria
expressing 8 different

colors
of fluorescent proteins.

Many more fluorescent proteins are engineered


Слайд 12 Use of green fluorescent protein (GFP) as a

Use of green fluorescent protein (GFP) as a reporter gene.Page 119

reporter gene.
Page 119


Слайд 13 Analyzing Translation – Western Blot

Analyzing Translation – Western Blot

Слайд 14 2 D Electrophoresis

2 D Electrophoresis

Слайд 15 Gene Expression
Transcriptional start
Translational start

Gene ExpressionTranscriptional startTranslational start

Слайд 16 Gene Expression
Gene copy number:
1. Plasmid copy

Gene ExpressionGene copy number: 1. Plasmid copy number:  The copy-number

number:
The copy-number of a plasmid in

the cell is determined by regulating the initiation of plasmid replication.
The initiation of plasmid replication may be controlled by:
the amount of available primer (RNA)
the amount of essential replication proteins
the function of essential replication proteins.

2. Gene dosage -> number of genes integrated into chromosome
- prokaryotic systems -> i.e. Transposons, phages, recombinantion
- mainly eukaryotic systems

Слайд 17 Incompatibility of plasmids:

Not all plasmids are able to

Incompatibility of plasmids:Not all plasmids are able to coexist in the

coexist in the same cell.
Plasmids which have the

same replication control functions are incompatible, and are assigned to the same incompatibility group (inc group).
Plasmids of one incompatibility group are related to each other, but cannot survive together in the same bacterial cell, as only different kinds of plasmids are compatible.

Ensures that we can make libraries -> just one plasmid taken up by one cell

Слайд 18 Homologous integration into chromosome
Insertion on Bacillus subtilis chromosome

Homologous integration into chromosomeInsertion on Bacillus subtilis chromosome

Слайд 19 Protein expression in prokaryotic systems
www.qiagen.com
So, this new story

Protein expression in prokaryotic systemswww.qiagen.comSo, this new story would be about


would be about vectors again.
Bacterial expression vectors
have

some distinct features:

Inducible promoter systems;

Protein fusions including fused tags;


Слайд 20 General advices for one who wants to produce

General advices for one who wants to produce gene expression in

gene expression in prokaryotes
1. Do not forget to cut

out the intron

2. Check orientation of insert

3. Do fusions with something In-frame

Most obvious and common mistakes:

4. No Post-translation modification
= no product activity


Слайд 21 www.wzw.tum.dewww.wzw.tum.de/gene-quantification/ www.wzw.tum.de/gene-quantification/ mrna.html
Introns
Not an issue
when you clone

www.wzw.tum.dewww.wzw.tum.de/gene-quantification/ www.wzw.tum.de/gene-quantification/ mrna.html IntronsNot an issuewhen you clone a cDNA

a cDNA


Слайд 22 Orientation of insert (could go backward, if cloned

Orientation of insert (could go backward, if cloned with same-type sticky

with same-type sticky ends) – use incompatible sticky ends
www.bch.bris.ac.ukwww.bch.bris.ac.uk/staff/

www.bch.bris.ac.uk/staff/ pfdgwww.bch.bris.ac.uk/staff/ pfdg/
teaching/teaching/genes.htm

Слайд 23 Fusion proteins.
When expressing
a fusion proteins,
ensure that

Fusion proteins.When expressing a fusion proteins, ensure that both of them

both of them are
in the same reading frame
www.bch.bris.ac.ukwww.bch.bris.ac.uk/staff/ www.bch.bris.ac.uk/staff/

pfdgwww.bch.bris.ac.uk/staff/ pfdg/
teaching/teaching/genes.htm

Слайд 24 PostTranslational modification
Eukaryotic cells have Golgi system
Prokaryotic

PostTranslational modification Eukaryotic cells have Golgi system Prokaryotic cells do not have itnucleusGolgi

cells do not have it
nucleus
Golgi


Слайд 25 Efficiency of expression in E.coli
Dependent of:
1. Type

Efficiency of expression in E.coliDependent of: 1. Type of transcription promoter

of transcription promoter and terminator
2. Affinity of mRNA and

prokaryotic ribosome

3. Amount of copies of transgene and its localization
(chromosome or plasmid)

4. Cellular localisation of the protein end-product

5. Efficiency of translation in the host organism

6. Stability of protein product in the host organism

Systems could be optimized on gene to gene basis.
No universal strategy possible


Слайд 26 Factors affecting transcription
Promoters (including regulated ones)
PROKARYOTIC!!!!
2.

Factors affecting transcription Promoters (including regulated ones)PROKARYOTIC!!!! 2. TerminatorsPROKARYOTIC!!!!

Terminators
PROKARYOTIC!!!!


Слайд 27 Variations between prokaryotic promoters are minimal
http://www.blc.arizona.edu/marty/
411

Variations between prokaryotic promoters are minimalhttp://www.blc.arizona.edu/marty/411

Слайд 28 Factors affecting translation
1. Ribosome binding site (RBS)
2. Codon

Factors affecting translation1. Ribosome binding site (RBS)2. Codon bias3. Stability of the transcript

bias
3. Stability of the transcript


Слайд 29 Ribosome binding site (RBS) = translation initiation site

Ribosome binding site (RBS) = translation initiation site complimentary to 16S rRNA

complimentary to 16S rRNA

end of gene
(minimize GC content)

Examining the second codon;
better AAA – lysin (13.9% of all E.coli genes).
Expression can vary 15 times.


Слайд 30

Codon Usage in E. coli & humans

Codon Usage in E. coli & humans

Слайд 31 Codon Optimization Strategies
Chemically synthesize new gene
Alter sequence of

Codon Optimization StrategiesChemically synthesize new geneAlter sequence of the gene of

the gene of interest
to match donor codons to

the codons
most frequently used in host organism
Express in different host
choose host with better matching codon usage
Use an engineered host cell
that overexpresses low abundance tRNAs


Слайд 32 Commercial E. coli strains encode for a number

Commercial E. coli strains encode for a number of the rare codon genes

of the rare codon genes


Слайд 33 Mitochondria and chloroplast genes
Alterations in the Standard

Mitochondria and chloroplast genes Alterations in the Standard Genetic Code in Mitochondria

Genetic Code in Mitochondria









Слайд 34 Factors affecting protein stability
Overall level of protease

Factors affecting protein stability Overall level of protease activity in bacterial

activity
in bacterial cells
2. N-terminal amino acid affects

protein half-life

3. Internal regions containing clusters of certain amino acids
can increase proteolysis

P proline E glutamic acid S serine T threonine

…. Mutate PEST aminoacids….


Слайд 35 Protease-deficient host strains
BL21, the work horse of

Protease-deficient host strains BL21, the work horse of E. coli expression,

E. coli expression,
is deficient in two proteases
encoded

by the lon (cytoplasmic)
and ompT (periplasmic) genes.

It is dangerous
to kill proteases,
it makes E.coli
grow much slowly
as proteases needed
for proper metabolism


Слайд 36 Inducible bacterial promoters
Why not to use constitutive,
always

Inducible bacterial promotersWhy not to use constitutive, always strong promoter? Induction

strong promoter?






















Induction
Because recombinant (alien) protein
is often

toxic for bacterial cell.
Bacteria tend to expel
harmful plasmids

Bacterial grow takes time….


Слайд 37 BL(DE3) inducible system and pET vectors (invented in

BL(DE3) inducible system and pET vectors (invented in 1984 by Bill

1984 by Bill Studier, on sale by Novagen)
1) T7

RNA polymerase gene is integrated in chromosome

under the control of a lac promoter and operator

2) lactose analogue, IPTG, causes the host to produce T7 RNA polymerase

3) The E. coli host genome also carries the lacI (repressor) gene

pET23


Gene of interest
is expressed from
strong T7 promoter


Слайд 38 Why repressor gene and gene of interest are

Why repressor gene and gene of interest are expressed from different

expressed from different DNA molecules?
Repressor gene expressed from

chromosome;
Gene of Interest expressed from plasmid

If too high repressor ? no transcription
(you need to increase expensive IPTG)

If too low repressor ? promoter is leaky
(active without IPTG)

Repressor is in chromosome,
because there it is best kept controlled there
(no plasmid loss, not too high expression)


Слайд 39 Where your expressed protein will be located?
Inclusion

Where your expressed protein will be located? Inclusion bodies(insoluble) Cytoplasm (soluble)Periplasmatic

bodies
(insoluble)
Cytoplasm
(soluble)
Periplasmatic space
(soluble or insoluble)
Secreted (!!)
E.Coli
can

not do that

Слайд 40 1. Inclusion bodies (most common case)
-- Inclusion

1. Inclusion bodies (most common case) -- Inclusion bodies are formed

bodies are formed through the accumulation
of folding intermediates


rather than from the native or unfolded proteins.

-- It is not possible to predict which proteins
will be produced as inclusion bodies.

-- Production of inclusion bodies
not dependent on the origin of protein,
the used promoters,
the hydrophobicity of target proteins...


Слайд 41 Electron micrograph of an inclusion body of the

Electron micrograph of an inclusion body of the protein prochymosin in

protein prochymosin in an E. coli cell
Page 116
Protein Folding


Слайд 42 Good side of inclusion bodies
inclusion bodies can be

Good side of inclusion bodiesinclusion bodies can be accumulated in the

accumulated in the cytoplasm
to much higher level (greater

than 25%)
than production as soluble form;

2) inclusion bodies is initially isolated
in a highly purified, solid, and concentrated state
by simple physical operation (centrifugation).

3) inclusion bodies have no biological activity.
For toxic proteins it may be the only one available;

4) inclusion bodies are resistant to proteolysis
That results in the high yield of protein production.


Слайд 43 SDS-PAGE analysis of recombinant protein produced as inclusion

SDS-PAGE analysis of recombinant protein produced as inclusion body hG-CSF mbel.kaist.ac.krmbel.kaist.ac.kr/research/ protein_en1.html

body
hG-CSF
mbel.kaist.ac.krmbel.kaist.ac.kr/research/ protein_en1.html


Слайд 44 Recovery of proteins from inclusion bodies
Is not a

Recovery of proteins from inclusion bodiesIs not a straightforward process, but

straightforward process, but road of trials and errors
Solubilization
Refolding
Choice of

solubilizing agents,
e.g., urea,
guanidine HCl,
or detergents,
plays a key role
in solubilization
efficiency

-- Refolding is initiated
by reducing concentration
of denaturant used to solubilize IBs.

Guandinium

-- Refolding competes with other reactions,
such as misfolding and aggregation
(both are leading to bad results)

-- Chaperones are helpful in refolding
(including chemical chaperones)


Слайд 45 Question of questions – how to purify your

Question of questions – how to purify your protein?

protein?


Слайд 46 Diversity of proteins could be exploited
Column chromatography
Matrix

Diversity of proteins could be exploited Column chromatographyMatrix particles usually packed

particles
usually packed in the column
in the form

of small beads.

A protein purification strategy
might employ in turn each of the three kinds of matrix
described below,

with a final protein purification
Of up to 10,000-fold.

Essential Cell Biology:
An Introduction to the Molecular Biology of the Cell


Слайд 47 Column chromatography
Different proteins
are retarded to different extents

Column chromatographyDifferent proteins are retarded to different extents by their interaction


by their interaction with the matrix,
they can be

collected separately
as they flow out from the bottom.

According to the choice of matrix,
proteins can be separated
according to
-- their charge,
-- their hydrophobicity,
-- their size,
-- their ability to bind to
particular chemical groups (!!)

Essential Cell Biology:
An Introduction to the Molecular Biology of the Cell


Слайд 48 (A) ION-EXCHANGE CHROMATOGRAPHY
Ion-exchange columns
are packed with small

(A) ION-EXCHANGE CHROMATOGRAPHYIon-exchange columns are packed with small beads that carry

beads
that carry
positive or negative charges
retarding proteins
of

the opposite charge.

The association between
a protein and the matrix
depends on the pH
and ionic strength of the solution
passing down the column.

These can be varied in a
controlled way to achieve an effective separation.

Essential Cell Biology:
An Introduction to the Molecular Biology of the Cell


Слайд 49 (B) GEL-FILTRATION CHROMATOGRAPHY
Gel-filtration columns
separate proteins
according to

(B) GEL-FILTRATION CHROMATOGRAPHYGel-filtration columns separate proteins according to their size on

their size
on tiny porous beads.

Protein molecules
that are

small enough to enter
the holes in the beads
are delayed and travel more slowly
through the column.

Proteins that cannot enter the beads are washed out of the column first.
Such columns also
allow an estimate of protein size.

Essential Cell Biology:
An Introduction to the Molecular Biology of the Cell


Слайд 50 (C) AFFINITY CHROMATOGRAPHY
Affinity columns
contain a matrix
covalently coupled

(C) AFFINITY CHROMATOGRAPHYAffinity columns contain a matrixcovalently coupled to a molecule

to a molecule that interacts specifically
with the protein

of interest

(e.g., an antibody, or an
enzyme substrate).

Proteins that bind specifically
to such a column
can finally be released
by a pH change or
by concentrated salt solutions,
and they emerge highly purified.

Essential Cell Biology:
An Introduction to the Molecular Biology of the Cell


Слайд 51 Protein electrophoresis
Essential Cell Biology:
An Introduction to

Protein electrophoresis Essential Cell Biology: An Introduction to the Molecular Biology of the Cell

the Molecular Biology of the Cell


Слайд 52 www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm
www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm

www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm www.unizh.chwww.unizh.ch/.../www.unizh.ch/.../Teaching_slide_showswww.unizh.ch/.../Teaching_slide_shows/ Lambda/sld015.htm

Слайд 53 Fusion proteins
increase production level
facilitate purification (taq)
detection of expression

Fusion proteinsincrease production levelfacilitate purification (taq)detection of expression (GFP fusion)Redirection of

(GFP fusion)
Redirection of proteins (secretion -> signal peptidases)
Surface display

(for screening of libraries)
Tandem arrays (for small peptides, toxic proteins,..)

Слайд 54 Most widely used purification strategy – to produce

Most widely used purification strategy – to produce your protein as

your protein as a fusion with something easily purifyable


(Invitrogen, Life Technologies, Novagen, QIAGEN):

6xHIS Tag

1. This small addition
rarely affects protein structure
to a significant degree

2. Interaction so strong,
it tolerates denaturing conditions
(could be used for
inclusion bodies purification)


Слайд 55 Histidine: a charged aminoacid
The affinity of this

Histidine: a charged aminoacid The affinity of this interaction is very

interaction is very high
which allows protein purification to

95% in a single step.

Stretch of six histidine residues
interacts with nickel ion
that is tightly bound to a NTA matrix  

Nitrilotriacetic acid (NTA) matrix

Histidine


Слайд 56 GST – fusion. Principle is the same. Binds

GST – fusion. Principle is the same. Binds to glutation

to glutation


Слайд 57 Require strong
binding to glutathione

Require strong
binding

Require strong binding to glutathione Require strong binding to glutathione GSTs

to glutathione
GSTs function catalytically to conjugate glutathione (GSH)


with a wide variety of electrophilic substrates

Слайд 58 Glutathione
GST from Schistosoma japonicum
1) Keeps fusion proteins

GlutathioneGST from Schistosoma japonicum 1) Keeps fusion proteins soluble2) Used for

soluble
2) Used for fusion purification
3) Used for protein

detection
with GST antibody

26 kDa tag


Слайд 59 FUSION PROTEIN BOUND TO GLUTATHIONE SEPHAROSE












Glutathione
GST
FOREIGN PEPTIDE










SEPHAROSE
Purification is

FUSION PROTEIN BOUND TO GLUTATHIONE SEPHAROSEGlutathioneGSTFOREIGN PEPTIDESEPHAROSEPurification is simple : --

simple :

-- WASH COLUMN EXTENSIVELY

-- ELUTE WITH REDUCED

GLUTATHIONE

-- RESULTS IN PURE GST FUSION PROTEIN

Слайд 61 Some problems of production in E. coli

Some problems of production in E. coli

Слайд 62 Some E.coli expression host considerations

Some E.coli expression host considerations

Слайд 63 Principal factors in bacterial expression

Principal factors in bacterial expression

Слайд 64 Type of expression vectors

Type of expression vectors

Слайд 65 Initiation of Transcription Promoters for Expression in

Initiation of Transcription  Promoters for Expression in ProkaryotesIn Escherichia coli

Prokaryotes
In Escherichia coli

- Lac system - plac

- Trp system
- synthetic systems – ptac, ptrc


In Bacillus

Слайд 66 The Lac promoter System

The Lac promoter System

Слайд 67 The trp promoter system

The trp promoter system

Слайд 68 E. coli Promoter Sites

E. coli Promoter Sites

Слайд 69 Synthetic E. coli promoters
-35
-10
ptac -> -35 box from

Synthetic E. coli promoters-35-10ptac -> -35 box from ptrp + -10 box from plac -> pt+ac

ptrp + -10 box from plac -> pt+ac


Слайд 71 Inverted Promoter System (from Salmonella)
-> for very

Inverted Promoter System (from Salmonella) -> for very toxic proteins

toxic proteins


Слайд 72 Bacillus
In 1872, Ferdinand Cohn, a student of Robert

BacillusIn 1872, Ferdinand Cohn, a student of Robert Koch, recognized and

Koch, recognized and named the bacterium Bacillus subtilis.
The

organism was made to represent a large and diverse genus of Bacteria, Bacillus,  and was placed in the family Bacillaceae.
The family's distinguishing feature is the production of endospores, which are highly refractile resting structures formed within the bacterial cells. Since this time, members of the genus Bacillus are characterized as Gram-positive, rod-shaped, aerobic or facultative, endospore-forming bacteria.

Flagellar stains of various species of Bacillus from CDC


Слайд 73 Bacillus
Antibiotic Producers: B. brevis (e.g. gramicidin, tyrothricin), B.

BacillusAntibiotic Producers: B. brevis (e.g. gramicidin, tyrothricin), B. cereus (e.g. cerexin,

cereus (e.g. cerexin, zwittermicin), B. circulans (e.g. circulin), B.

laterosporus (e.g. laterosporin), B. licheniformis (e.g. bacitracin), B. polymyxa (e.g. polymyxin, colistin), B. pumilus (e.g. pumulin) B. subtilis (e.g. polymyxin, difficidin, subtilin, mycobacillin).
Pathogens of Insects: B. larvae, B. lentimorbis, and B. popilliae are invasive pathogens. B. thuringiensis forms a parasporal crystal that is toxic to beetles.
Pathogens of Animals: B. anthracis, and B. cereus.  B. alvei, B. megaterium, B. coagulans, B. laterosporus, B. subtilis, B. sphaericus, B. circulans, B. brevis, B. licheniformis, B. macerans, B. pumilus, and B. thuringiensis have been isolated from human infections.

The Genus Bacillus includes two bacteria of significant medical importance, B. anthracis, the causative agent of anthrax, and B. cereus, which causes food poisoning. Nonanthrax Bacillus species can also cause a wide variety of other infections, and they are being recognized with increasing frequency as pathogens in humans.

Слайд 74 Bacillus
Bacillus strains used as production organisms:

BacillusBacillus strains used as production organisms:     -

- B. subtilis

- B. brevis
- B. licheniformis

Transformation systems:
- via competent cells (during transition from vegetative cells -> sporulation, cell can take up DNA (ss) when population reaches a metabolic state called competence)
- protoplast
- bacteriophage-mediated transduction

Vectors:
- replicating plasmids (pUB110, pE194, pC194, pHP13, shuttle vectors)
-> replicating plasmids with temperature-sensitive origin of replication
(replication stops above certain temp. -> pE194 stops above 45ºC)
- integrative vectors (normally shuttle vectors)

Promoters:
- aprE promoter -> induction with onset of sporulation
- amylase promoter -> growth-phase and nutrition regulated promoter (induction at end of exponential growth + repression by glucose)
- sacB promoter (levansurase) -> not regulated
- spac promoter -> hybrid promoter (subtilis phage + lac operator) -> induction with IPTG

Слайд 75 Bacillus as expression host

Bacillus as expression host

Слайд 76 Bacillus as expression host

Bacillus as expression host

Слайд 77 Products produced in Prokaryotic Systems
Restriction Endonucleases ->

Products produced in Prokaryotic Systems Restriction Endonucleases -> produced in E.

produced in E. coli
L- Ascorbic Acid (Vitamin C) ->

recombinant Erwinia herbicola (gram-negative bacterium)
Synthesis of Indigo (blue pigment -> dye cotton /jeans) -> produced in E. coli
Amino Acids -> produced in Corynebacterium glutamicum (gram-positive bacterium)
Lipases (laundry industry) -> from Pseudomonas alcaligenes produced in Pseudomonas alcaligenes
Antibiotica (most of them from Streptomyces, other gram-positive bacteria, fungi) -> produced in recombinant Streptomyces and fungi (Penicillium)
Biopolymers (PHB -> biodegradable plastics) -> produced in E. coli (stabilized with parB)


Слайд 78 Expression in Eukaryotic Systems
Yeast

- Saccharomyces cerevisiae

Expression in Eukaryotic SystemsYeast - Saccharomyces cerevisiae (baker’s yeast) - Pichia

(baker’s yeast)
- Pichia pastoris

Insect Cells – Baculovirus



Mammalian Cells

Слайд 79 Expression in Yeast
Autonomous replicating vectors -> shuttle vectors

Expression in YeastAutonomous replicating vectors -> shuttle vectors

Слайд 80 Expression in Saccharomyces cerevisiae Autonomous replicating systems

Expression in Saccharomyces cerevisiae Autonomous replicating systems

Слайд 81 Expression in Saccharomyces cerevisiae Integrative systems
Probability for integration higher

Expression in Saccharomyces cerevisiae Integrative systemsProbability for integration higher with linear fragments !

with linear fragments !


Слайд 82 Expression in Saccharomyces cerevisiae

Expression in Saccharomyces cerevisiae

Слайд 83 Expression in Saccharomyces cerevisiae

Expression in Saccharomyces cerevisiae

Слайд 84 Yeast are efficient secretors !
Secretory expression preferred if:
->

Yeast are efficient secretors !Secretory expression preferred if:-> if product toxic->

if product toxic
-> if many S-S bonds need to

be closed

Слайд 85 Expression in S. cerevisiae – Pichia pastoris
Problems with

Expression in S. cerevisiae – Pichia pastorisProblems with production in S.

production in S. cerevisiae:

For some proteins production level low
Hyperglycosylation

(more than 100 mannose residues in N-glycosylation)
Sometimes secretion not good -> protein stack in cells (periplasma)
S. cerevisiae produces high amount of EtOH -> toxic for the cells -> effects level of production

Advantages of production in Pichia pastoris:

Highly efficient promoter, tightly regulated (alcohol oxidase -> AOX, induced by MeOH)
Produces no EtOH -> very high cell density -> secretion very efficient
Secretes very few proteins -> simplification of purification of secreted proteins

Слайд 86 Expression in Pichia pastoris Integrative systems

Expression in Pichia pastoris Integrative systems

Слайд 87 Expression in Pichia pastoris

Expression in Pichia pastoris

Слайд 88 Expression in Pichia pastoris

Expression in Pichia pastoris

Слайд 89 Expression in Insect cells
Baculovirus:
-> infects invertebrates (insects)
-> in

Expression in Insect cellsBaculovirus:-> infects invertebrates (insects)-> in infection cycle 2

infection cycle 2 forms of baculovirus are formed:

-> single virus particle
-> in protein matrix (polyhedron) trapped clusters of viruses

-> during late stage of infection massive amount of polyhedron produced -> strong promoter
-> polyhedron not required for virus production
-> polyhedron promoter optimal for heterologous protein production in insect cells


Слайд 90 Expression in Insect cells
Baculovirus:
-> Autographa californica multiple nuclear

Expression in Insect cellsBaculovirus:-> Autographa californica multiple nuclear polyhedrosis virus (AcMNPV)

polyhedrosis virus (AcMNPV) many used as expression vector

-> Production

of recombinant baculovirus:
1. create a transfer vector (E. coli based plasmid with AcMNPV DNA – polyhedrin promoter/terminator + flanking sequences) -> gene of interest cloned downstream of promoter

2. Insect cells are cotransfected with virus (AcMNPV) + transfer vector
-> in some double infected cells -> double crossover event (recombination)
-> produce recombinant virus (bacmid -> E. coli - insect cell baculovirus shuttle vector)

-> cells infected with recombinant virus -> produce plaques (lack of polyhedrin)

3. DNA hydridisation + PCR used to identify recombinant virus

4. Infection of insect cells with concentrated stock of verified recombinant virus
-> 4-5 days later protein harvested

Слайд 91 Baculovirus expression system

Baculovirus expression system

Слайд 92 Why this system?

Insect cells have almost the same

Why this system?Insect cells have almost the same posttranslational modifications as

posttranslational modifications as mammalian cells
Higher expression level than mammalian

cells

Baculovirus expression system


Слайд 93 Mammalian cell expression system
1. Why do we use

Mammalian cell expression system1. Why do we use that system? ->

that system?
-> to get full complement of

posttranslational modifications on proteins

2. Developed cell lines:
-> short term (transient) expression -> autonomous replicating systems -> viral origins (SV40)
- African green monkey kidney (COS)
- baby hamster kidney (BHK)
- human embryonic kidney (HEK-239)

-> long term (stable) expression -> integration into chromosome -> viral origins
- chinese hamster ovary (CHO)

Слайд 94 Mammalian cell expression system

Mammalian cell expression system

Слайд 95  Gene expression in mammalian cell lines

A convenient alternative

 Gene expression in mammalian cell linesA convenient alternative for setting up

for setting up mammalian cell facilities – get a

comprehensive service from us. We will achieve stable expression of the gene of your interest in mammalian cells.

Customer provides:

- Mammalian vector with the gene (cDNA) to be expressed. We accept plasmid and retroviral vectors
- Sequence of the gene and map of the construct for transfection
Cell line or information about the cell line to be transfected.

Our service includes:

- Transfection of the cells. In case of a retroviral vector, virus production and cell infection
- Antibiotic selection and generation of stable transfected (infected) cell clones. At least 10 independent clones will be selected and grown
- Quantitative assay of the gene (cDNA) expression level in each transfected clone by RNA isolation followed by Northern hybridisation and/or RT-PCR
- Selection of the best expressing clone
- Cell freezing and depositing
- Duration: 3-6 months (depending on the cell growth rate), allow 1month in addition if the cell line is not available in our collections
Customer receives:

- Detailed report on experiments and data obtained.
- Two vials of transfected cells (the best expressing clone)
- We will deposit the transfected cells in our collection as a precaution against accidental loss of the clone.
Price guide:
Price per transfection and selection of at least 10 clones: £3500.


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