Question

What statement is FALSE in regard to how RNA polymerase (RNAP) interacts with promoter DNA vs. non-promoter DNA?

A. By reducing the stability of non-promoter complexes, sigma allows RNAP core to find the promoter sequence much faster

B. When sigma is released from the RNAP, the core and RNA transcript form a ternary complex with DNA

C. By increasing the stability of non-promoter complexes, sigma allows RNAP core to slide along DNA much faster and find the promoter sequence easier

D. When sigma is released from the RNAP, the core and RNA transcript are bound extremely tightly onto DNA until termination

Answer 1

The false statement about RNA polymerase's interaction with DNA concerns the role of sigma in increasing the stability of non-promoter complexes, which is incorrect. Sigma actually decreases these complexes' stability, aiding RNAP in locating promoters.

Step-by-step explanation:

The statement that is FALSE in regard to how RNA polymerase (RNAP) interacts with promoter DNA versus non-promoter DNA is: 'By increasing the stability of non-promoter complexes, sigma allows RNAP core to slide along DNA much faster and find the promoter sequence easier.'

In fact, sigma factors in bacterial RNAP help the core enzyme to locate promoter sequences by decreasing the stability of non-promoter complexes, thereby promoting the dissociation of RNAP from nonspecific DNA sequences. This facilitates a more efficient search for the correct promoter sequences where transcription can be initiated. Once sigma is released from RNAP, forming a ternary complex with DNA and the RNA transcript, the transcription proceeds with high fidelity until it reaches a termination sequence.