A. A single RNA polymerase transcribes genes that encode mRNAs, tRNAs, and rRNA. B. Sigma () subunit detaches from RNA polymerase shortly after transcription has initiated. C. The C-terminal domain of the polymerase is phosphorylated after transcription has initiated.
The C-terminal domain of the polymerase is phosphorylated after transcription has initiated. Which of the following statements regarding transcription only apply to prokaryotes and not to eukaryotes?
A) All three eukaryotic RNA polymerases recognize the same promoters as prokaryotic polymerases. B) None of the eukaryotic RNA polymerases recognizes prokaryotic promoters. C) Only eukaryotic RNA polymerase I recognizes prokaryotic promoters.
A. Early in initiation, the RNA exit channel of RNA polymerase is blocked by the polymerase itself. B. Early in initiation, the RNA exit channel of RNA polymerase is blocked by the sigma factor.
The α subunit of E. coli RNAP plays an important role in the recognition of many promoters by binding to the A+T-rich UP element, a DNA sequence located upstream of the recognition elements for the ς subunit, the −35 and −10 hexamers.
Finally, RNA polymerase II and some additional transcription factors bind to the promoter.
The exact functions of the larger subunits are still unknown. In Escherichia coli the β′ subunit is the largest polypeptide and is involved in the binding of RNA polymerase to DNA3; the β subunit is responsible for both rifampicin4 and streptolydigin5,6 resistance.
The σ subunit of bacterial RNA polymerase (RNAP) has been implicated in all steps of transcription initiation, including promoter recognition and opening, priming of RNA synthesis, abortive initiation and promoter escape.
coli RNA polymerase. Recognition and binding of DNA promoter elements by RNA polymerase set the start site for transcription initiation. In Escherichia coli, these elements are recognized by a σ factor when σ is present in RNA polymerase holoenzyme, (σ plus core [β, β′, α, α, and ω]) (15, 36).
RNA polymerase and the necessary transcription factors bind to the promoter sequence and initiate transcription. Promoter sequences define the direction of transcription and indicate which DNA strand will be transcribed; this strand is known as the sense strand.
The alpha subunit (alpha) of RNA polymerase (RNAP) is critical for assembly of polymerase and positive control of transcription initiation in Escherichia coli. Here, we report that alpha also plays a role in transcription elongation, and this involves a direct interaction between alpha and NusA factor.
The results indicate that the ω subunit facilitates the association of the primary σ factor with the RNAP core, thereby allowing efficient transcription of highly expressed genes.
The ω subunit facilitates assembly of RNAP and stabilizes assembled RNAP. In order to bind promoters, RNAP core associates with the transcription initiation factor sigma (σ) to form RNA polymerase holoenzyme.
Sigma factors are subunits of all bacterial RNA polymerases that are responsible for determining the specificity of promoter DNA binding and efficient initiation of RNA synthesis (transcription). The first sigma factor discovered was the sigma70 (σ70) of the highly studied bacterium Escherichia coli.
The sigma (σ) subunit of RNA polymerase (RNAP) controls all transcription initiation steps, from recognition of the −10/−35 promoter elements, upon formation of the closed promoter complex (RPc), to stabilization of the open promoter complex (RPo) and stimulation of the primary steps in RNA synthesis.
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).