Is TFIIB a protein?
Structure. TFIIB is a single 33kDa polypeptide consisting of 316 amino acids. TFIIB makes protein-protein interactions with the TATA-binding protein (TBP) subunit of transcription factor IID, and the RPB1 subunit of RNA polymerase II.
What is the function of TFIIB?
TFIIB carries out at least two functions: it interacts directly with the TATA-binding protein (TBP) and helps to recruit RNA polymerase II into the initiation complex. The sequence of TFIIB reveals a potential zinc-binding domain and an imperfect duplication of approximately 70 amino acids.
Do Archaea use Sigma proteins?
σ-Factors are always found associated with bacterial RNAP but have been functionally replaced by other proteins in the more complex RNAP characteristic of eukaryotes and Archaea. However, σ-like factors are found in the chloroplasts of photosynthetic eukaryotes which are descended from a cyanobacterium.
What is BRE in transcription?
The B recognition element (BRE) is a DNA sequence found in the promoter region of most genes in eukaryotes and Archaea. The BRE is a cis-regulatory element that is found immediately near TATA box, and consists of 7 nucleotides.
Can promoters be downstream?
In molecular biology, a downstream promoter element (DPE) is a core promoter element. Like all core promoters, the DPE plays an important role in the initiation of gene transcription by RNA polymerase II. It is located about 28–33 nucleotides downstream of the transcription start site.
Does Tfiib bind to TATA box?
Transcription factor TFIIB is essential for the formation of RNA polymerase II initiation complexes where it binds to the TATA-binding protein (TBP) complex with DNA and recruits RNA polymerase II. TFIIB requires at least seven base pairs of DNA on either side of the TATA box to form a stable TFIIB-TBP-DNA complex.
Is sigma factor a protein?
A sigma factor (σ factor or specificity factor) is a protein needed for initiation of transcription in bacteria. It is a bacterial transcription initiation factor that enables specific binding of RNA polymerase (RNAP) to gene promoters.
How do sigma factors work?
Sigma factor proteins promote binding of RNA polymerase to promoter sites within DNA sequences to allow for initiation of transcription. Sigma factors are specific for the gene and are affected by the cellular environment. Sigma factors can regulate at both a transcription and translational level.
What is a major disadvantage to a bacterial cell of having an operon?
What is a major disadvantage to a bacterial cell of having an operon? If there is a mutation in a regulatory region, none of the proteins will be synthesized. RNA polymerase. Which of the following statement(s) about basal transcription factors is(are) TRUE?
How does a downstream promoter work?
The downstream promoter element (DPE) functions cooperatively with the initiator (Inr) for the binding of TFIID in the transcription of core promoters in the absence of a TATA box.
What is a eukaryotic promoter?
Promoter sequences define the direction of transcription and indicate which DNA strand will be transcribed; this strand is known as the sense strand. Many eukaryotic genes have a conserved promoter sequence called the TATA box, located 25 to 35 base pairs upstream of the transcription start site.
How does TFIIB interact with the B recognition element?
TFIIB makes sequence-specific protein-DNA interactions with the B recognition element (BRE), a promoter element flanking the TATA element. There are six steps in the mechanism of TFIIB action in the formation of the PIC and transcription initiation: RNA polymerase II is recruited to DNA through the TFIIB B core and B ribbon.
What makes up the core domain of TFIIB?
TFIIB is made up of four functional regions: the C-terminal core domain; the B linker; the B reader and the amino terminal zinc ribbon. TFIIB makes protein-protein interactions with the TATA-binding protein (TBP) subunit of transcription factor IID, and the RPB1 subunit of RNA polymerase II.
What causes the binding of TFIIB to TBP?
Studies have shown that the binding of TFIIB to TBP is affected by the length of the polyglutamine tract in TBP. Extended polyglutamine tracts such as those found in neurodegenerative diseases cause increased interaction with TFIIB.
How many amino acids are in TFIIB polypeptide?
Structure. TFIIB is a single 33kDa polypeptide consisting of 316 amino acids. It was originally thought to be essential at all promoters in order to recruit RNA polymerase II and initiate transcription; however, recent research has shown that a depletion in TFIIB is not lethal to cells and transcription levels are not significantly affected.