About POL / Polymerase (RNA) (DNA directed) Polypeptide:
RNA polymerase (abbreviated RNAP or RNApol, and officially DNA-directed (dependent) RNA polymerase) is a molecular biology enzyme synthesizing RNA from a DNA template.
RNAP locally opens the double-stranded DNA using the enzyme helicase. One strand of the exposed nucleotides can be utilized as a template for RNA production, a process known as transcription. Before RNAP can begin unwinding the DNA at that place, a transcription factor and its accompanying transcription mediator complex must be linked to a DNA binding site known as a promoter region. RNAP not only begins RNA transcription, but it also guides nucleotides into position, aids attachment and elongation, has inherent proofreading and replacement capabilities, and termination recognition capability. RNAP can form chains as long as 2.4 million nucleotides in eukaryotes.
Polymerase (RNA) (DNA directed) Polypeptide Structure
A single RNA polymerase species transcribes all kinds of RNA in most prokaryotes. The "core" of E. coli RNA polymerase is made up of five subunits: two alpha () subunits of 36 kDa, a beta () subunit of 150 kDa, a beta prime subunit (′) of 155 kDa, and a tiny omega () subunit. A sigma () factor attaches to the core, resulting in the formation of the holoenzyme. After transcription begins, the factor might unbind and let the core enzyme continue its activity. The core RNA polymerase complex takes the shape of a "crab claw" or "clamp-jaw" structure, with an internal channel running the length of it. Although they have many more subunits, eukaryotic and archaeal RNA polymerases have a similar fundamental structure and function.
Control of the gene transcription process affects gene expression patterns, allowing a cell to adapt to a changing environment, perform specialized roles within an organism, and sustain essential metabolic processes required for survival. As a result, it is not surprising that RNAP activity is protracted, complex, and highly regulated. More than 100 transcription factors have been found in Escherichia coli bacteria that affect the activity of RNAP.