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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.
In biotechnology applications, T7 RNA polymerase is commonly used to transcribe DNA that has been cloned into vectors that have two (different) phage promoters (e.g., T7 and T3, or T7 and SP6) in opposite orientation.
This also removes the need for an RNA primer to initiate RNA synthesis, as is the case in DNA replication. The non -template (sense) strand of DNA is called the coding strand , because its sequence is the same as the newly created RNA transcript (except for the substitution of uracil for thymine).
A Rho factor acts on an RNA substrate. Rho's key function is its helicase activity, for which energy is provided by an RNA-dependent ATP hydrolysis. The initial binding site for Rho is an extended (~70 nucleotides, sometimes 80–100 nucleotides) single-stranded region, rich in cytosine and poor in guanine, called the rho utilisation site (rut), in the RNA being synthesised, upstream of the ...
There are also a number of RNA-dependent RNA polymerases that use RNA as their template for synthesis of a new strand of RNA. For instance, a number of RNA viruses (such as poliovirus) use this type of enzyme to replicate their genetic material. [58] Also, RNA-dependent RNA polymerase is part of the RNA interference pathway in many organisms. [59]
The bacterial RNA polymerase, a leading enzyme involved in formation of a transcription bubble, uses DNA template to guide RNA synthesis. [6] It is present in two main forms: as a core enzyme, when it is inactive, and as a holoenzyme, when it is activated.
The 5′ end is the part of the RNA molecule that is transcribed first, and the 3′ end is transcribed last. The 3′ end is also where the poly(A) tail is found on polyadenylated RNAs. [1] [9] Messenger RNA (mRNA) is RNA that has a coding region that acts as a template for protein synthesis (translation).
In bacteria, the same enzyme catalyzes the synthesis of mRNA and non-coding RNA (ncRNA). RNAP is a large molecule. The core enzyme has five subunits (~400 kDa ): [ 26 ]