Transcription Initiation in Eukaryotes
Summary
TLDRThis video delves into the intricate process of transcription initiation in eukaryotes, focusing on the pivotal role of RNA polymerase II and the general transcription factors known as TF IIs. It explains how TF II D, with the aid of TF II A, recognizes and binds to the TATA box, initiating a cascade of factor recruitments, including TF II B, E, F, and H. Highlighting the importance of TF II H's ATPase and helicase activities, the video illustrates the formation of the minimal pre-initiation complex and the phosphorylation dynamics of RNA polymerase II's CTD. It concludes with the initiation of transcription and the role of elongation factors, providing a comprehensive understanding of gene expression regulation in eukaryotic cells.
Takeaways
- 🔬 RNA polymerase II is responsible for transcribing all protein-coding genes in eukaryotes.
- 🧬 General Transcription Factors (TF II), including TF II D, A, B, F, E, H, play crucial roles in the transcription initiation process.
- 🎯 The TATA box is an important promoter sequence recognized by TF II D and TF II A for transcription initiation.
- 🔄 TF II D binding to the TATA box initiates the recruitment of other transcription factors, forming a complex.
- 🔗 TF II B is recruited to the complex by TF II D, which in turn recruits RNA polymerase II and TF II F.
- 🌀 TF II E and TF II H are the last to join, with TF II H possessing ATPase and helicase activities, essential for unwinding DNA.
- 🔋 The CTD of RNA polymerase II undergoes dynamic phosphorylation at different stages of transcription, affecting its function.
- 🌡 The phosphorylation at Ser 5 during initiation recruits the capping enzyme, while Ser 5 and Ser 2 are phosphorylated during elongation.
- 🔬 The assembly of RNA polymerase II with the six general transcription factors forms the minimal pre-initiation complex.
- 🔄 Regulatory Transcription factors such as CBF, CREB, SP1, and others modulate the transcription process.
- 📝 The transcription process involves the addition of nucleotides to the transcription machinery, leading to RNA synthesis by RNA polymerase II.
Q & A
What is the primary enzyme responsible for transcribing protein-coding genes in eukaryotes?
-RNA polymerase II is the primary enzyme responsible for transcribing all protein-coding genes in eukaryotes.
What are the general transcription factors involved in eukaryotic transcription initiation?
-The general transcription factors involved in eukaryotic transcription initiation are the TF II factors, which include TF II D, A, B, F, E, and H.
What is the role of the TATA box in eukaryotic transcription initiation?
-The TATA box is an important consensus sequence in the promoter region of DNA, recognized by the TBP region of TF II D, which aids in the binding of the transcription machinery to the DNA.
How does TF II A assist in the transcription initiation process?
-TF II A aids in the recognition of the TATA box by TF II D, which is a critical step in the assembly of the transcription initiation complex.
What is the function of TF II B in the transcription initiation complex?
-TF II B binds to the complex after TF II D has bound to the TATA box and it helps in recruiting RNA polymerase II and TF II F to the complex.
What is the significance of the CTD of RNA polymerase II during transcription?
-The CTD of RNA polymerase II undergoes dynamic phosphorylation throughout the transcription process, which is crucial for the recruitment of the capping enzyme and the regulation of transcription.
What is the role of TF II H in the transcription initiation?
-TF II H is an important transcription factor with ATPase and helicase activity, which unwinds the DNA at the start point and phosphorylates the CTD of RNA polymerase II.
What happens to the DNA structure during transcription initiation due to TF II H?
-Due to the action of TF II H, the DNA is unwound, providing an open form of DNA necessary for the RNA polymerase to initiate transcription.
What constitutes the minimal pre-initiation complex in eukaryotic transcription?
-The minimal pre-initiation complex in eukaryotic transcription is formed by the assembly of RNA polymerase II with the six general transcription factors.
Are there any regulatory transcription factors that influence the transcription initiation process?
-Yes, there are regulatory transcription factors like CBF, CREB, and SP1 that play a role in modulating the transcription initiation process.
How does the RNA polymerase II synthesize the RNA molecule during transcription?
-RNA polymerase II moves along the DNA template from the 3' to 5' strand and synthesizes the RNA molecule with the help of elongation factors.
Outlines
🔬 Transcription Initiation in Eukaryotes
This paragraph introduces the topic of transcription initiation in eukaryotes, focusing on the role of RNA polymerase II and the general transcription factors known as TF II factors. It explains that RNA polymerase II is responsible for transcribing all protein-coding genes and requires assistance from various TF II factors, including TF II D, A, B, F, E, and H. The paragraph also mentions the importance of the TATA box and other consensus sequences in the promoter region of DNA. The process begins with TF II D recognizing and binding to the TATA box, which is aided by TF II A. This binding event recruits TF II B, and subsequently, RNA polymerase II and TF II F join the complex, facilitated by TF II B. The paragraph concludes with the description of the assembly of the minimal pre-initiation complex, which includes RNA polymerase II and the six general transcription factors.
Mindmap
Keywords
💡Transcription Initiation
💡RNA polymerase II
💡General Transcription Factors
💡TATA Box
💡Transcription Start Point
💡Promoter
💡TF II D
💡TF II B
💡TF II H
💡CTD Phosphorylation
💡Pre-Initiation Complex
Highlights
RNA polymerase II transcribes all protein coding genes in eukaryotes.
General Transcription Factors, TF II factors, are essential for transcription in eukaryotes.
TF II D, A, B, F, E, H are key components of the transcription process.
The TATA Box is an important promoter sequence recognized by TF II D and TF II A.
TF II D binding to the TATA box is a crucial step in transcription initiation.
TF II B recruitment follows TF II D binding, forming a complex with RNA polymerase.
RNA polymerase II and TF II F are recruited to the complex by TF II B.
TF II E and TF II H are additional factors that join the transcription complex.
TF II H has ATPase and helicase activity, which is vital for DNA unwinding.
Phosphorylation of the CTD of RNA polymerase II is dynamic and stage-specific.
Serine 5 phosphorylation at the initiation stage recruits the capping enzyme.
During elongation, both serine 5 and serine 2 are phosphorylated.
Serine 2 phosphorylation occurs only during the termination stage.
The assembly of RNA polymerase II with the six general transcription factors forms the minimal Pre-Initiation Complex.
Regulatory Transcription factors like CBF, CREB, SP1 play a role in controlling transcription.
Nucleotides are added to the transcription machinery, initiating the transcription process.
RNA polymerase II moves along the 3' to 5' strand to synthesize the RNA molecule with the help of elongation factors.
Transcripts
In the series of videos we have been discussing abt the Transcription in Prokaryotes and we
also discussed the proteins and enzymes in Eukaryotic transcription if u want to watch
that video first the link is in the description.
Now in this video we will be discussing abt the Transcription Initiation in Eukaryotes.
Before we get into the detailed mechanism we know it is the RNA polymerase II that transcribes
all protein coding genes and we also need several General Transcription Factors called
the TF II factors that includes TF II D , A , B , F , E , H
Now lets get to the transcription initiation, here in this diagram we can we the DNA having
TATA Box and a Transcription Start Point.
There are several other consensus sequences on DNA of which this TATA BOX is one of the
important sequences of Promoter. Other Consenses sequences are shown in the diagram displayed
here ( u can watch the complete video of Eukaryotic promoter , linked in the description )
Going forward now , we see we have TF II D first in the run, it has got TBP region which
is able to recognise TATA box and this recognition of TATA box is aided another Transcription
factor TF II A. So from here TF II D recognises the TATA box on DNA and binds to it as shown
in the diagram. and the binding of TFII D to the TATA box
recruits another Transcription factor TF II B , which comes in and joins the complex .
Now we have RNA Polymerase shown in the diagram below which marks it enters along with the
TRANSCRIPTION Factor II F . The RNA Polymerase and TF II F is recruited to the complex by
the TF II B and finally we have another two factors TF II E and TF II H .
First of all TF II E joins in and then this E factor inturn recruits TF II H.
This TF II H is important Transcription factor , since it has ATpase and Helicase activity.
It unwinds DNA at start point and also phosphorylates the CTD of RNA polymerase II.
The CTD of RNA polymerase has dynamic phosphorlyation through out the Transcription process. It
is shown in the diagram , at initiation stage Ser 5 is phosphorylated which recruits capping
enzyme , while as during elongation ser 5 as well as ser 2 is phosphorylated and at
the end during termination only serine 2 is phosphorylated.
Now getting back to the mechanism , we see the unwinding has occurred due to TF II H
, which gives us open form DNA as shown in the diagram.
The assembly of RNA polymerase II with the 6 General Transcription factors constitutes
us the MINIMAL Pre Initiation Complex.
There are other Regulatory Transcription factors which regulated the transcription , like we
have CBF , CREB , SP1
More over to drive the Transcription nucleotides are added to the transcription machinery where
first of all some factors disassemble and then this Polymerase can initiate the Transcription.
the RNA Poly II moves forward on 3 prime to 5 prime strand and synthesises RNA molecule….by
the help of elongation factors.
So this is how Transcription is initiated in the eukaryotes by the RNA polymerase enzyme
along with the T Fs.
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