What is the structure of RNA polymerase?
RNA polymerase “core” from E. coli consists of five subunits: two alpha (α) subunits of 36 kDa, a beta (β) subunit of 150 kDa, a beta prime subunit (β′) of 155 kDa, and a small omega (ω) subunit. A sigma (σ) factor binds to the core, forming the holoenzyme.
Where is the RNA polymerase II phosphorylated?
the promoter
RNAP II containing unphosphorylated CTD is recruited to the promoter, whereas the hyperphosphorylated CTD form is involved in active transcription. Phosphorylation occurs at two sites within the heptapeptide repeat, at Serine 5 and Serine 2.
Does RNA polymerase have quaternary structure?
The crystals of RNA polymerase of T. In Type II crystal the enzyme molecules are arranged in an orderly two-dimensional lattice and thus we could analyze the molecular structure by optical filtering of the negatively stained images. On the basis of these results, a quaternary structure is proposed for RNA polymerase.
Why is RNA polymerase phosphorylated?
The C-terminal domain of RNA polymerase II undergoes a cycle of phosphorylation which allows it to temporally couple transcription with transcription-associated processes. The characterization of hitherto unrecognized metazoan elongation phase CTD kinase activities expands our understanding of this coupling.
Which subunit of RNA polymerase 2 is highly phosphorylated?
carboxy-terminal domain
The largest subunit of Pol II contains a repetitive carboxy-terminal domain (CTD) that becomes highly phosphorylated during transcription. mRNA-capping enzyme binds only to phosphorylated CTD, whereas other processing factors may bind to both phosphorylated and unphosphorylated forms.
What regulates polyadenylation and the length of the Polya tail?
the nuclear poly
Poly(A) tail length is controlled by the nuclear poly(A)-binding protein regulating the interaction between poly(A) polymerase and the cleavage and polyadenylation specificity factor. J Biol Chem.
Where does the RNA polymerase holoenzyme bind to the DNA?
To start with, the RNA polymerase holoenzyme locates and binds to promoter DNA. Next, it separates the two strands of DNA and exposes a portion of the template strand. At this point, the DNA and the holoenzyme are said to be in an ‘open promoter complex’ and the section of promoter DNA that is within it is known as a ‘transcription bubble’.
When does holoenzyme bind to the sigma factor?
When RNA polymerase and the sigma factor interact the resulting group of proteins is known as the RNA polymerase ‘holoenzyme’. Transcription takes place in several stages. To start with, the RNA polymerase holoenzyme locates and binds to promoter DNA.
How is the structure of RNA polymerase conserved?
The basic architecture of multi-subunit RNA polymerases is conserved throughout the the bulk of the enzyme ( \\ and in bacteria), a homo- or hetero-dimer of smaller subunits on the periphery of the enzyme involved in assembly (the \ dimer in bacteria), and at least one accessory subunit (\ in bacteria).
How does RNA polymerase ( RNAP ) control gene expression?
Initiation of transcription is a primary means for controlling gene expression. In bacteria, the RNA polymerase (RNAP) holoenzyme binds and unwinds promoter DNA, forming the transcription bubble of the open promoter complex (RPo). We have determined crystal structures, refined to 4.14 Å-resolution, …