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Bacterial transcription is the process in which a segment of bacterial DNA is copied into a newly synthesized strand of messenger RNA (mRNA) with use of the enzyme RNA polymerase. The process occurs in three main steps: initiation, elongation, and termination; and the result is a strand of mRNA that is complementary to a single strand of DNA.
The number of transcription factors found within an organism increases with genome size, and larger genomes tend to have more transcription factors per gene. [ 14 ] There are approximately 2800 proteins in the human genome that contain DNA-binding domains, and 1600 of these are presumed to function as transcription factors, [ 3 ] though other ...
A sigma factor is a protein needed only for initiation of RNA synthesis in bacteria. [12] Sigma factors provide promoter recognition specificity to the RNA polymerase (RNAP) and contribute to DNA strand separation, then dissociating from the RNA polymerase core enzyme following transcription initiation. [13]
transcription factor – a substance, such as a protein, that contributes to the cause of a specific biochemical reaction or bodily process; promoter – a region of DNA that initiates transcription of a particular gene; Sigma factor – specialized bacterial co-factors that complex with RNA Polymerase and encode sequence specificity
The former is found in bacteria, archaea, and eukaryotes alike, sharing a similar core structure and mechanism. [1] The latter is found in phages as well as eukaryotic chloroplasts and mitochondria, and is related to modern DNA polymerases. [2] Eukaryotic and archaeal RNAPs have more subunits than bacterial ones do, and are controlled differently.
The diagram includes 8 RNA polymerases however the number can vary depending on cell type. The image also includes transcription factors and a porous, protein core. Transcription factories, in genetics describe the discrete sites where transcription occurs in the cell nucleus, and are an example of a biomolecular condensate.
The TATA box is also found in 40% of the core promoters of genes that code for the actin cytoskeleton and contractile apparatus in cells. [5] The type of core promoter affects the level of transcription and expression of a gene. TATA-binding protein (TBP) can be recruited in two ways, by SAGA, a cofactor for RNA polymerase II, or by TFIID. [11]
A sigma factor (σ factor or specificity factor) is a protein needed for initiation of transcription in bacteria. [1] [2] It is a bacterial transcription initiation factor that enables specific binding of RNA polymerase (RNAP) to gene promoters. It is homologous to archaeal transcription factor B and to eukaryotic factor TFIIB. [3]