Question

Which protein or domain within bacterial RNA polymerase contacts DNA using minor groove contact?

A. Sigma 70 domain 2.3

B. Sigma 70 domain 4.2

C. The CTD of the alpha subunit

D. The NTD of alpha

Answer 1

The Sigma 70 domain 4.2 within bacterial RNA polymerase makes contact with DNA through the minor groove. This domain is essential for the initiation stage of bacterial transcription as it recognizes promoter sequences to position the RNA polymerase for mRNA synthesis.

Step-by-step explanation:

The protein or domain within bacterial RNA polymerase that contacts DNA using the minor groove contact is Sigma 70 domain 4.2. This domain is part of the sigma factor which assists RNA polymerase in finding the correct initiation sites for transcription by recognizing promoter sequences upstream of the transcription start site.

The sigma factor is crucial during the initiation stage of bacterial transcription, as it binds to the promoter region of DNA and helps to position the RNA polymerase properly for the synthesis of mRNA. Once transcription has started, the sigma factor, including Sigma 70 domain 4.2, dissociates from the polymerase.

In contrast, the alpha subunit CTD (C-terminal domain) and NTD (N-terminal domain) play different roles, such as facilitating the assembly and interactions with regulatory factors but are not directly involved in minor groove contact with DNA.