Siswa setyahadi 2014 Regulation of gene expression.

siswa setyahadi 2014 Regulation of gene expression

siswa setyahadi 2014

Gene: A DNA segment that encodes the all genetic information required to produce functional biological products (Note that: not all transcripts are messenger RNA). G. enome: A. complete set of genes of a given species. Gene expression: A process of gene transcription and/or gene translation

siswa setyahadi 2014 Most of prokaryotic genomes contain 4.000 or so genes, although some simple bacteria have only 500-600 genes. The human genomes contain about 35.000 genes

siswa setyahadi 2014 Specificity of gene expression Temporal specificity (also called stage specificity) Spatial specificity (also called tissue specificity)

siswa setyahadi 2014 Type of gene expression a. Constitutive expression Some genes are essential and necessary for life, and therefore are continuously expressed, such as those enzymes involved in TCA These genes are called housekeeping genes.

siswa setyahadi 2014 b. Induction and repression b. Induction and repression In addition to constitutively expressed genes, all cells contain genes that are expressed only in special circumstances Such genes are said to be regulated Both prokaryotic and eukaryotic cells adapt to changes in their environment by turning the expression genes on and off

siswa setyahadi 2014 Some genes demonstrate higher expression level once being activated, such as enzymes involved in DNA repairing. It is called induced expression. On the other hand, some genes are repressed and their expression levels are lower, such as the enzymes for Trp synthesis when Trp is abundant. It is called repressed expression

siswa setyahadi 2014 Regulatory Elements Gene expression is a multiple-level process. Gene expression is also a multiple components process. In general, every step that is required to make an active gene product can be the focus of a regulatory event. In fact, the most important stage for the regulation of most genes is when transcription initiation because it wouldbe a waste to make the RNA if neither the RNA nor its encoded protein is needed.

siswa setyahadi 2014 Basic Elements Basic elements that regulate the transcription include: a.Special DNA sequences b.Regulatory proteins c.DNA-protein interaction and protein-protein interaction d.RNA polymerase

siswa setyahadi 2014 a. Special DNA sequence Gene expression of prokaryotic systems is regulated based on the operon model which is composed of structural genes, promoter, operator and other regulatory sites. promoter Other regulatory sites operator Structural gene

siswa setyahadi 2014 Operonsthatinclude two to six genes transcribed as a unit are common; some operons contain 20 or more genes. Is a set of adjacent genes whose mRNA is synthesized in one piece, plus the adjacent regulatory signals that affect transcription of the genes DNA Repressor Binding site (operator) promoter A B C Regulatory sequences Activator binding site Genes transcribed as a unit

siswa setyahadi 2014 Types of operons Inducible: substrate needs to be present before transcription of genes involved in its breakdown occurs. Mostly metabolic pathways-breaking things down for energy, e.g. lac operon Repressible: anabolic pathways (building things)- no reason to make protein to build a molecule that is already available. E.g. tryptophan operon. An E. coli cell won’t waste a bunch of energy making tryptophan if it is available from the medium. Tryptophan represses its own synthesis

RNA synthesis is blocked by repressor

Promoter. The DNA sequence that RNA-pol can bind and initiate the transcription.

As mentioned earlier, RNA polymerases bind to DNA and initiate transcription at promoters. The nucleotide sequences of promoters vary considerably, affecting the binding affinity of RNA polymerases and thus the frequency of transcription initiation. By convention, DNA sequences are shown as they exist in the nontemplate strand, with the 5-terminus on left

siswa setyahadi 2014 Most base substitutions in the -10 regions have a negativeeffect on function. For example, mutations that result in a shift away from the consensus sequence usually decreasepromoter function; conversely, mutations toward consensus usually enhance promoter function. Most E. coli promoters have a sequence close to a consensus

siswa setyahadi 2014 Operator. The DNA sequence adjacent to the structural genes that the repressor protein can bind to and prevent the transcription of structural genes The operators are generally near a promoter. Coding sequences

siswa setyahadi 2014 b. Regulatory proteins For prokaryotic systems: Repressor: Itbindstotheoperatorand prevent the transcription, known as negative regulation. Activator: It associates with DNA near the initiation point, resulting in the increase of RNA-pol binding affinity and the enhancement of the transcription efficiency.

siswa setyahadi 2014 Specific factor: It facilitates the binding of RNA-pol to particular DNA sequence once associating with other elements. Catabolite gene activator protein (CAP) is a typical one. For some genes, RNA pol cannot bind to the promoter without CAP.

siswa setyahadi 2014 Regulation by means of a repressor protein that blocks transcription is referred to as negative regulation. Activators provide a molecular counterpoint to repressors; they bind to DNA and enhance the activity of RNA polymerase at a promoter; this is positive regulation.

General concepts Prokaryotes Eukaryotes Controls Chromosome organization Transcription Post-transcription Translation Post translation

siswa setyahadi 2014 o In prokaryotes, gene expression is controlled by the external environment. Ex. fuel availability o In eukaryotes, gene expression is controlled by the internal environment. Ex. Hormones, toxic substances, etc.

siswa setyahadi 2014 Regulation of Gene Expression in Prokaryotes

siswa setyahadi 2014 In prokaryotes, control of gene expression occurs at 3 levels: Transcription Translation Post translation

siswa setyahadi 2014 Figure 17-1 RNA polymerase DNA mRNA Transcriptional control Translational control Post-translational control Protein Ribosome RNA polymerase Onset of transcription Life span (stability) of mRNA Translation rate Protein activation or inhibition (by chemical modification)

siswa setyahadi 2014 Common Features Prokaryotic systems were developed earlier. Their internal and external conditions are relative simple. Prokaryotic genes are polycistron systems, that is, several relevant genes are organized together in a series format. The majority of gene regulation is negative. Inducers are used to remove the repression.

siswa setyahadi 2014 Lac Operon

siswa setyahadi 2014 Lactose metabolism in E. coli Galactoside permease: transport lactose into the cell across the cell membrane β -Galactosidase: hydrolyze lactose to glucose and galactose or convert lactose to allolactose Thiogalactoside transacetylase: may involved in the detoxification.

siswa setyahadi 2014 Inducible Expression For lacl· system, all three enzymes are expressed continuously regardless of the presence of lactose. Forlacl+system, bacteria do not express these three enzymes when glucose is available. However, bacteria produce those enzymes if lactose is present and glucose is absent

siswa setyahadi 2014 lac gene demonstrate how bacteria use different types of nutrient as the source of carbon. Glucose is the most abundant and prevailing nutrient, and use of it is the most efficient way. Lactose is an alternative choice when glucose is exhausted.

siswa setyahadi 2014 Sequence of lac operon lac operon has a weak promoter (TTTACA/TATGTT), and has a basal expression level. CAP(Catabolite gene activator protein) binding site is at - 60 region. CAP is a homodimer with binding ability to DNA and cAMP.

Glucose inhibits the formation of cAMP. When glucose is present, [cAMP] is lower. Only after glucose is exhausted, [cAMP] becomes higher. The CAP-cAMP complex is formed, and this complex binds to the CAP binding site on lac operon.

siswa setyahadi 2014 Situation 1

siswa setyahadi 2014 lac/ gene has its own promoter, and its expression can produce Lac/ repressor. The tetrameric Lac repressor binds to the lac operator site 01ac· The binding blocks the RNA-pol moving on DNA template, and no lacZ, lacY, and lacA are expressed. No use of lactose due to the negative regulation.

siswa setyahadi 2014 Situation 2

siswa setyahadi 2014 Thegalactosidase is weaklyexpressed (at the basal level}. When lactose is present, it is converted to allolactose that binds to the repressor. The repressor can no longer bind to the operator, and lac gene can be expressed. Allolactose and IPTG are referred to as inducer.

siswa setyahadi 2014 Inducers

siswa setyahadi 2014 Presence of Lactose The lacZ, YandARNAtranscriptis very unstable and could be degraded quickly. Therefore, the synthesis of three enzymes will be cease under normal condition.

siswa setyahadi 2014 Situation 3 When glucose is present, the [cAMP] is low, no CAP-cAMP is formed and the expression of the lac operon is still low.

siswa setyahadi 2014 Situation 4 When glucose is absent and lactose is present, the CAP-cAMP complex binds to the CAP site to activate the lac gene.

siswa setyahadi 2014 lac Operon Undergoes Positive Regulation

siswa setyahadi 2014 Coordinate Regulation It is the interaction between CAP-cAMP and RNA- polthat greatly stimulates the activation of lac gene. The positive regulation and removal of the negative regulation of Lac/ repressor allow bacteria to use lactose as the source of carbon. The positive regulation of CAP-cAMP and the negative regulation of Lac/ repressor constitute a coordinated regulation unit.

siswa setyahadi 2014 Regulation of Gene Expression in Eukaryotes

siswa setyahadi 2014 In eukaryotes, control of gene expression occurs at these same 3 levels + 2 other levels: Chromosome organization (remodeling) RNA processing

siswa setyahadi 2014 Transcription in the eukaryotic nucleus is separated from translation in the cytoplasm in both space and time. Regulation of eukaryotic gene expression occurs at multiple levels, including transcription, processing, mRNA stability, and translation. However, like prokaryotic gene, the initiation of transcription is also a crucial regulation point for eukaryotic gene expression

siswa setyahadi 2014 Structural Features Large genome : 3 x 10 9 bps, 35,000 genes. Monocistron : One gene is transcribed into one mRNA, and one mRNA then is translated into one polypeptide. Repeated sequences : different lengths and different frequencies. Often inverted repeats: complementary and opposite orientation. Split genes : separated by introns and exons alternatively.

siswa setyahadi 2014 Regulation Features RNA-pol: 3 forms (I, II, and Ill) for different RNAs Changes of chromosomal structure: Hypersensitive site Base modification : 5°/o of A are methylated. Isomers-conversion: from negative supercoil in the native form to positive supercoil after activation Histone changes

siswa setyahadi 2014 Positive regulation : more accurate regulation and more efficient. Transcription and translation are separated : at different locations. Post-transcriptional modification : more complicated than prokaryotes. Regulation through intercellular and intracellular signals : hormone.

siswa setyahadi 2014 Gene Regulatory Sequences The expression of eukaryotic protein coding genes is regulated by multiple protein-binding DNA sequences, genericallyreferred to as gene regulatory sequences. These include promoters, enhancer and silencer.

siswa setyahadi 2014 Cis-acting Elements Note that the gene regulatory sequences are also called cis-acting elements since they are on the same DNA molecule as the gene being controlled (cis is Latin for “on the side”) Promoter: TATA box, CAAT box, and GC box

siswa setyahadi 2014 TATA Box Sequence: TATAAAA Location: - 25-- 30 bp Function: It is the binding site for TFII D, which is required for RNA polymerase binding. Without TATA box, the 5'-end of transcriptional product is random.

siswa setyahadi 2014 CAAT Box Sequence: GCCAAT Location: - - 80 bp Function:Itis the binding site for CTF1 (CAAT- binding transcription factor) and C/EBP. The DNA-binding domain of TF1 is rich in basic Aas, and most likely it is in the alpha-helical conformation. C/EBP binds to DNA in a dimer known as leucine zipper. Eukaryotes frequently have CAAT boxes, a strong promoter, usually located around -80 relative to the transcription start site

siswa setyahadi 2014 GC Box Sequence: GGGCGG Location: -30 - -110 bp Function: It is the binding site for a protein called Sp1. The DNA-binding domain of Sp1 is near the C- terminus and contains three zinc fingers. One or more copies of GC-rich sequences are also referred to as CpG island. These genes, which generally are transcribed at low rates, have been found upstream from the transcription start sites of "housekeeping genes."

siswa setyahadi 2014 Enhancer Transcription from many eukaryotic promoters can be stimulated by control elements located thousands of base pairs away from the start site. Such long-distance transcription control elements, referred to as enhancers, are common in eukaryotic genomes but fairly rare in bacterial genomes. An enhancer is typically 100-200 bp long. Enhance has no functionality without promoter. Enhances can exert their stimulatory actions over distances of several thousand base pairs in presence of promoter. They can be upstream, downstream, or even in the midst of a transcribed gene.

siswa setyahadi 2014 Their functions are dependent on recognition by specifictranscription factors. A specific transcription factor bound at an enhancer element stimulates transcription by interacting with RNA polymerase II at a near by promoter

Silencer Silencers are control elements that can inhibit transcription. A specific transcription factor that binds to a silencer control element and blocks transcription is called a repressor.

siswa setyahadi 2014 Trans-acting Factors The protein transcription factors that bind to these specific sequences are known as trans-acting factors in that the genes that encode them can be on different DNA molecules {different chromosomes). Trans-acting proteins bind indirectly to cis-acting elements and then regulate the transcription initiation. Due to the complexity of eukaryotic transcription,there are many protein factors in transcription. The transacting factors can be transcription factors (TF).

siswa setyahadi 2014 General Structure of TF DNA-binding domain Activation domain Protein-protein interaction domain

siswa setyahadi 2014 Promoter and Regulatory Proteins RNA pol II complex TFIID co-activator

siswa setyahadi 2014 CTD of RNA-pol II is an important point of interaction with mediators and other protein complexes. Cofactors facilitate the TF assembly.

siswa setyahadi 2014 Transcription Repressor

siswa setyahadi 2014 DNA-protein interactions Regulatory proteins have discrete DNA-binding domains of particular structure, i,.e., binding motif They can recognize DNA sequences in a affinity 10 4 -10 6 times higher than usual The AA side chains of regulatory proteins interact with bases of DNA through H bonds

siswa setyahadi 2014 Motif When several local peptides of defined secondary structures are close enough in space, they are able to form a particular "super- secondary " structure. Zinc finger HLH (helix-loop-helix) HTH (helix-turn-helix) Leucine zipper

Leucine Zipper Yeast activator protein in GCN4 (PDB ID 1YSA)

siswa setyahadi 2014 Zinc Finger

siswa setyahadi 2014 Steroid Hormone Receptor

siswa setyahadi 2014 Gene Specific Regulatory Proteins As mentioned earlier, in order to initiate transcription, RNA polymerase II requires the assistance of general (basal) transcriptionfactors since no eukaryotic RNA polymerase binds specifically to promoters by itself. This binding process involves at least six basal transcription factors (labeled as TFIIs, transcription factors for RNA polymerase II).

siswa setyahadi 2014 Withonlythese transcription(orbasal) factors and RNA polymerase II attached (the basal transcription complex), the gene is transcribed at a low or basal rate. However, the rate of transcription can be further increased by binding of other regulatory DNA binding proteins to additional gene regulatory sequences (such as the enhancer regions). These regulatory DNA binding proteins are called gene-specific transcription factors (or transactivators} because they are specific to the gene involved. They also can be called activators, inducers, repressors, or nuclear receptors.

siswa setyahadi 2014 In activation of gene, the DNA between the enhancer and the promoter loops out to allow the transcription factors bound to the enhancer to interact with the general transcription factors, other regulatory proteins or the RNA polymerase itself to increase the rate of transcription. Gene repressor proteins that inhibit the transcription of specific genes in eukaryotes also exist. For example, when a repressor has attachedto the silencer region near the enhancers, activators can be prevented from binding to the enhancers, and transcription is repressed.

siswa setyahadi 2014 Note that, as already noted, eukaryotic RNA polymeraseshave little or no intrinsic affinity for their promoters. The initiation of transcription is almost always dependent on the action of multiple activator proteins. One important reason is that the storage of DNA within chromatin effectively renders most promoters inaccessible, so genes are normally silent in the absence of other regulation. Thus, positive regulations predominate in all systems characterized of eukaryotes.

Nucleus Chromatin (DNA-protein complex) 1. Chromatin remodeling 2. Transcription “Open” DNA (Some DNA not closely bound to proteins) 3. RNA processing Primary transcript (pre-mRNA) Cap Tail Mature mRNA Cytoplasm 4. mRNA stability 5. Translation Degraded mRNA (mRNA lifespan varies) mRNA Polypeptide Active protein 6. Post-translational modification (folding, transport, activation, degradation of protein)

siswa setyahadi 2014 Regulating the macromolecular composition of Cells Which genes? Amount of primary RNA transcript RNA processing/transport RNA degradation Proteins translation from mRNA Protein modification/transport Covalent/Allosteric modulation Degradation

siswa setyahadi 2014 1.Principle of gene regulation Molecular circuits ------------------------------- House keeping genes; constitutive gene expression Inducible; induction; repressible; repression RNA polymerase binds to DNA at promoters

Many prokaryotic genes are clustered and regulated in operons

siswa setyahadi 2014 Lactose metabolism in E. coli

siswa setyahadi 2014 The lac operon

siswa setyahadi 2014 The control of gene expression Each cell in the human contains all the genetic material for the growth and development of a human Some of these genes will be need to be expressed all the time These are the genes that are involved in of vital biochemical processes such as respiration Other genes are not expressed all the time They are switched on an off at need © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 Operons An operon is a group of genes that are transcribed at the same time. They usually control an important biochemical process. They are only found in prokaryotes. © NobelPrize.org Jacob, Monod & Lwoff © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 The lac Operon  The lac operon consists of three genes each involved in processing the sugar lactose  One of them is the gene for the enzyme β-galactosidase  This enzyme hydrolyses lactose into glucose and galactose © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 Adapting to the environment E. coli can use either glucose, which is a monosaccharide, or lactose, which is a disaccharide However, lactose needs to be hydrolysed (digested) first So the bacterium prefers to use glucose when it can © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 Four situations are possible 1.When glucose is present and lactose is absent the E. coli does not produce β-galactosidase. 2.When glucose is present and lactose is present the E. coli does not produce β-galactosidase. 3.When glucose is absent and lactose is absent the E. coli does not produce β-galactosidase. 4.When glucose is absent and lactose is present the E. coli does produce β-galactosidase © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 1. When lactose is absent A repressor protein is continuously synthesised. It sits on a sequence of DNA just in front of the lac operon, the Operator site The repressor protein blocks the Promoter site where the RNA polymerase settles before it starts transcribing Regulator gene lac operon Operator site zya DNA I O Repressor protein RNA polymerase Blocked © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 2. When lactose is present A small amount of a sugar allolactose is formed within the bacterial cell. This fits onto the repressor protein at another active site (allosteric site) This causes the repressor protein to change its shape (a conformational change). It can no longer sit on the operator site. RNA polymerase can now reach its promoter site zya DNA IO © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 2. When lactose is present A small amount of a sugar allolactose is formed within the bacterial cell. This fits onto the repressor protein at another active site (allosteric site) This causes the repressor protein to change its shape (a conformational change). It can no longer sit on the operator site. RNA polymerase can now reach its promoter site Promotor site zya DNA I O © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 3. When both glucose and lactose are present This explains how the lac operon is transcribed only when lactose is present. BUT….. this does not explain why the operon is not transcribed when both glucose and lactose are present. © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 When glucose and lactose are present RNA polymerase can sit on the promoter site but it is unstable and it keeps falling off Promotor site zya DNA IO Repressor protein removed RNA polymerase

siswa setyahadi 2014 4. When glucose is absent and lactose is present Another protein is needed, an activator protein. This stabilises RNA polymerase. The activator protein only works when glucose is absent In this way E. coli only makes enzymes to metabolise other sugars in the absence of glucose Promotor site zya DNA IO Transcription Activator protein steadies the RNA polymerase © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 Summary CarbohydratesActivator protein Repressor protein RNA polymerase lac Operon + GLUCOSE + LACTOSE Not bound to DNA Lifted off operator site Keeps falling off promoter site No transcription + GLUCOSE - LACTOSE Not bound to DNA Bound to operator site Blocked by the repressor No transcription - GLUCOSE - LACTOSE Bound to DNA Bound to operator site Blocked by the repressor No transcription - GLUCOSE + LACTOSE Bound to DNA Lifted off operator site Sits on the promoter site Transcription © 2007 Paul Billiet ODWSODWS

siswa setyahadi 2014 Two Main Mechanisms to Regulate Transcription in Bacteria Use of different  factors These recognize different classes of promoters Allows coordinated expression of different sets of genes Binding other proteins (transcription factors) to promoters These recognize promoters of specific genes These may bind small signaling molecules These may undergo post-translational modifications The protein’s affinity toward DNA is altered by ligand binding or post-translational modifications Allows expression of a specific genes in response to signals in the environment

siswa setyahadi 2014 Regulation by  Factors Sigma 70 consensus– Responsible for the Bulk of mRNA Sigma 32 consensus– Responsible for “Heat Shock” mRNA

siswa setyahadi 2014 Regulation by Transcription Factors

siswa setyahadi 2014 Bacterial Operons Operons provide for coordinated expression of genes. Include promoter, binding sites for activators and repressors, and functional groupings of genes. In this example, A, B, and C are transcribed as one polycistronic mRNA that is translated into three proteins

siswa setyahadi 2014 The trp operon Is similar to the lac operon, but functions somewhat differently Promoter DNA Active repressor Inactive repressor Lactose Active repressor Tryptophan Inactive repressor lac operon trp operon Operator Genes Figure 11.1C

siswa setyahadi 2014 Regulation of Gene Expression in Eukaryotes Not all genes in an organism are “turned on” in all cells or at all times in particular cell. All cells of an organism have the same set of genes, but cells from different tissues look very different and function very different from one another. -Development, Stem cells, differentiated cells - In an adult organism, certain genes are active or inactive at different times.

siswa setyahadi 2014 Differentiated Cells

siswa setyahadi 2014 Lactose Metabolism in E. coli Lactose is a secondary Carbon source Glucose preferred. Enzymes for lactose metabolism are inducible. Lactose transport into the cell Lactose is hydrolysis into monosaccharides

siswa setyahadi 2014 The lac Operon has Three Sites for Binding the Lac Repressor Lac Repressor binds with high affinity to O 1 (also O 2&3 ) Allolactose reduces affinity

Model for cooperative binding LacR tetramer Sugar binding Domain tetramer “core” DNA binding dimer headpieces

siswa setyahadi 2014 IPTG (lactose analog) causes subtle conformational change – loss of affinity

siswa setyahadi 2014 Lac inducer IPTG, structurally similar to lactose

siswa setyahadi 2014 Helix-Turn-Helix Motif is Common in DNA- Binding Proteins One of the helixes (red) fits into the major groove of DNA Four DNA-binding helix- turn-helix motifs (gray) in the Lac repressor

siswa setyahadi 2014 Binding of Proteins to DNA Often Involves Hydrogen Bonding

siswa setyahadi 2014 Conformational Change in Repressor Upon Ligand Binding Binding of allolactose or other lactose analogs, such as IPTG induces a conformational change in repressor The ligand-bound repressor dissociates from DNA Genes needed for lactose metabolism are transcribed

siswa setyahadi 2014 Activation of Transcription of the lac Operon by CRP cAMP receptor protein (CRP) is a positive regulator of the lac operon CRP binds to the lac operon in the absence of glucose Binding of CRP stimulates expression of the lac operon

siswa setyahadi 2014 CRP-RNAP contacts compensate for weak RNAP- DNA A region of CRP interacts favorably with RNA polymerase, stimulating transcription of genes in the lac operon

siswa setyahadi 2014 Combined Effects of Glucose and Lactose on the lac Operon When lactose is low, repressor is bound: inhibition When lactose is high, repressor dissociates permitting transcription When glucose is high, CRP is not bound and transcription is dampened When glucose is low, cAMP is high and CRP is bound: activation

siswa setyahadi 2014 The trp Operon – Dual Control

siswa setyahadi 2014 Dimeric Trp Repressor Binds to DNA in the Presence of Tryptophan Tryptophan required for repression Notice that helix-turn-helix motifs interact with DNA via the major groove

SOS response in E. coli

siswa setyahadi 2014 Site-Specific Recombin- ation Regulates flagellin genes in Salmonella

Regulation of Transcription in Eukaryotes General transcription factors TATA box binding protein (TBP) Transcription factors for the assembly of the initiation complex Promoter proximal / distal enhancer binding factors Homeodomain proteins share similarities with helix-turn-helix bacterial counterparts nut often involve water bridges between DNA and protein Leucine zippers are made of two amphipathic polypeptides. One side of each peptide is hydrophobic, facilitating dimerization Zinc fingers form elongated loops held together by a single Zn ++ ion

siswa setyahadi 2014 Homeodomain Proteins Also a helix-turn- helix interacts with DNA via the major groove One domain of multidomain – multiprotein complex

siswa setyahadi 2014 Leucine Zipper – Dimerization Domains B (for basic) –Zip proteins

siswa setyahadi 2014 Eukaryotic Promoters and Regulatory Proteins Integration of multiple signals, chromatin, local and remote binding sites, assembly, histone modifcation, scaffolding proteins

siswa setyahadi 2014 Regulation of transcription of GAL genes in yeast

siswa setyahadi 2014 Chromatin Structure/ Activation Domains

siswa setyahadi 2014 Gene silencing by RNA interference

The Hox gene clusters direct human development in much the same way as flies

siswa setyahadi 2014 Homeotic mutations transform one body part into another.

siswa setyahadi 2014 Butterfly colors on a Fruit Fly – Sean Carrol – U of Wisconsin

Siswa setyahadi 2014 Regulation of gene expression.

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Siswa setyahadi 2014 Regulation of gene expression.

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