Question

RNA polymerase subunit that recognises and binds to promoter is

• A. $\alpha$-subunit
• B. $\beta$-subunit
• C. $\gamma$-subunit
• D. $\sigma$-subunit

Answer 1

The correct option is D $\sigma$-subunit

DNA-directed RNA polymerases (also known as DNA-dependent RNA polymerases) are responsible for the polymerization of ribonucleotides into a sequence complementary to the template DNA.

RNA polymerases are enzymes and are composed of a variable number of subunits.

(1) α subunit initiates and activates the core assembly to form a platform on which the beta subunits can interact.

(2) β subunit is involved in chain initiation and catalysis of polynucleotide formation in the template-dependent manner.

(3) γ subunit facilitates assembly of RNA polymerase (RNAP) and stabilizes assembled RNAP.

(4) σ subunit/ factor is a protein needed only for initiation of RNA synthesis. It is a bacterial transcription initiation factor that enables specific binding of RNA polymerase to gene promoters.

So, the answer is D.