AL-RAISALMILL M. ALAWI
●The order of addition of the general transcription factors (and RNA
GENERAL TRANSCRIPTION FACTORS polymerase) to the preinitiation complex in vitro is as follows:
● Eukaryotic RNA polymerases, rely on proteins called transcription ○ TFIID (or TFIIA 1 TFIID)
factors to show them the way to their respective promoters ○ TFIIB
SUCH FACTORS ARE GROUPED INTO TWO CLASSES: ○ TFIIF 1 polymerase II
● general transcription factors ○ TFIIE
● gene-specific transcription factors (activators). ○ TFIIH. The V
● General transcription factors and the three polymerases alone ● Figure 11.2 shows the results of a footprinting study on the DA and ●
allow for only minimal transcription control, whereas Activators DAB complexes.
help cells exert exquisitely fine control over transcription. ● Reinberg and colleagues used two different reagents to cut the ●
11.1 Class II Factors protein–DNA complexes:
● The general transcription factors combine with RNA polymerase to ○ 1.) 1,10-phenanthroline (OP)-copper ion complex, which
form a preinitiation complex that is competent to initiate creates hydroxyl radicals ●
transcription as soon as nucleotides are available. ○ 2.) DNase I
● This tight binding involves the formation of an open promoter ● RNA polymerase II is a very big protein, so we would expect it to
complex in which the DNA at the transcription start site has melted cover a large stretch of DNA and leave a big footprint. ●
to allow the polymerase to read it. STRUCTURE AND FUNCTION OF TFIID ●
The Class II Preniation Complex ● TFIID is a complex protein containing a TATA-box binding protein
● Contains: polymerase II and six general transcription factors named (TBP) and 13 core TBP-associated factors (TAFs, or more
TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH. specifically, TAFIIs). The T
● `Class II general transcription factors and RNA polymerase II bind ● The subscript “II” was traditionally used when the context was ●
in a specific order to the growing preinitiation complex, at least in unclear, because TBP also participates in the transcription of class I
vitro. and III genes and is associated with different TAFs (TAFIs and
● Danny Reinberg, as well as Phillip Sharp and their colleagues: TAFIIIs) in class I and III preinitiation complexes, respectively.
○ performed DNA gel mobility shift and DNase and hydroxyl ● The TATA-Box-Binding Protein (TBP) binds to the minor groove
radical footprinting experiments of the TATA box and is highly evolutionarily conserved:
● Figure 11.1a presents the results of a gel mobility shift assay ○ Yeast, fruit flies, plants, and humans have
performed by Danny Reinberg and Jack Greenblatt and their TATA-box-binding domains that are more than 80%
colleagues using TFIIA, TFIID, TFIIB, and TFIIF, as well as RNA identical in amino acid sequence.
polymerase II. ○ These domains encompass the carboxyl-terminal 180 ●
Four Distinct Preiniitiation Complexes amino acids of each protein
● Transcription factors bind to class II promoters in the following order ● Tjian’s group demonstrated the importance of the
in vitro: carboxyl-terminal 180 amino acids of TBP when they showed by
● They added TFIID and TFIIA to the DNA containing the adenovirus DNase I footprinting that a truncated form of human TBP. ●
major late promoter binds to the TATA box forming the DA complex ● How does the TBP in TFIID bind to the TATA box?
● TFIIB in addition to D and A it forms a DAB complex ● Diane Hawley and Robert Roeder, showed convincingly that the
● Next, TFIIF helps RNA polymerase bind to a region extending from TBP in TFIID binds to the minor groove of the TATA box. ●
at least position -34 to position +17, two new complexes appeared ● How does TFIID associate with the TATA box minor groove?
now it is DABPolF complex ● Nam-Hai Chua, Roeder, and Stephen Burley and colleagues TATA-
●The order of addition of the general transcription factors (and RNA
GENERAL TRANSCRIPTION FACTORS polymerase) to the preinitiation complex in vitro is as follows:
● Eukaryotic RNA polymerases, rely on proteins called transcription ○ TFIID (or TFIIA 1 TFIID)
factors to show them the way to their respective promoters ○ TFIIB
SUCH FACTORS ARE GROUPED INTO TWO CLASSES: ○ TFIIF 1 polymerase II
● general transcription factors ○ TFIIE
● gene-specific transcription factors (activators). ○ TFIIH. The V
● General transcription factors and the three polymerases alone ● Figure 11.2 shows the results of a footprinting study on the DA and ●
allow for only minimal transcription control, whereas Activators DAB complexes.
help cells exert exquisitely fine control over transcription. ● Reinberg and colleagues used two different reagents to cut the ●
11.1 Class II Factors protein–DNA complexes:
● The general transcription factors combine with RNA polymerase to ○ 1.) 1,10-phenanthroline (OP)-copper ion complex, which
form a preinitiation complex that is competent to initiate creates hydroxyl radicals ●
transcription as soon as nucleotides are available. ○ 2.) DNase I
● This tight binding involves the formation of an open promoter ● RNA polymerase II is a very big protein, so we would expect it to
complex in which the DNA at the transcription start site has melted cover a large stretch of DNA and leave a big footprint. ●
to allow the polymerase to read it. STRUCTURE AND FUNCTION OF TFIID ●
The Class II Preniation Complex ● TFIID is a complex protein containing a TATA-box binding protein
● Contains: polymerase II and six general transcription factors named (TBP) and 13 core TBP-associated factors (TAFs, or more
TFIIA, TFIIB, TFIID, TFIIE, TFIIF, and TFIIH. specifically, TAFIIs). The T
● `Class II general transcription factors and RNA polymerase II bind ● The subscript “II” was traditionally used when the context was ●
in a specific order to the growing preinitiation complex, at least in unclear, because TBP also participates in the transcription of class I
vitro. and III genes and is associated with different TAFs (TAFIs and
● Danny Reinberg, as well as Phillip Sharp and their colleagues: TAFIIIs) in class I and III preinitiation complexes, respectively.
○ performed DNA gel mobility shift and DNase and hydroxyl ● The TATA-Box-Binding Protein (TBP) binds to the minor groove
radical footprinting experiments of the TATA box and is highly evolutionarily conserved:
● Figure 11.1a presents the results of a gel mobility shift assay ○ Yeast, fruit flies, plants, and humans have
performed by Danny Reinberg and Jack Greenblatt and their TATA-box-binding domains that are more than 80%
colleagues using TFIIA, TFIID, TFIIB, and TFIIF, as well as RNA identical in amino acid sequence.
polymerase II. ○ These domains encompass the carboxyl-terminal 180 ●
Four Distinct Preiniitiation Complexes amino acids of each protein
● Transcription factors bind to class II promoters in the following order ● Tjian’s group demonstrated the importance of the
in vitro: carboxyl-terminal 180 amino acids of TBP when they showed by
● They added TFIID and TFIIA to the DNA containing the adenovirus DNase I footprinting that a truncated form of human TBP. ●
major late promoter binds to the TATA box forming the DA complex ● How does the TBP in TFIID bind to the TATA box?
● TFIIB in addition to D and A it forms a DAB complex ● Diane Hawley and Robert Roeder, showed convincingly that the
● Next, TFIIF helps RNA polymerase bind to a region extending from TBP in TFIID binds to the minor groove of the TATA box. ●
at least position -34 to position +17, two new complexes appeared ● How does TFIID associate with the TATA box minor groove?
now it is DABPolF complex ● Nam-Hai Chua, Roeder, and Stephen Burley and colleagues TATA-
