Which termination mechanism requires the Rho protein?

Which termination mechanism requires the Rho protein?

• A. Rho-independent
• B. Promoter termination
• C. Rho-dependent
• D. Intrinsic termination

Answer: (C)

The main concept is how transcription ends in bacteria and the specific role of the Rho protein. Rho-dependent termination needs a protein factor, Rho, to function. Rho binds to a rut site on the newly made RNA and uses ATP to move along the transcript toward the RNA polymerase. When it catches up to a paused polymerase, Rho disrupts the RNA–DNA hybrid and releases the RNA, terminating transcription. In contrast, intrinsic (Rho-independent) termination doesn’t require any protein. It relies on the RNA forming a strong hairpin followed by a string of uracils, which causes the polymerase to pause and dissociate on its own. Promoter-associated termination isn’t a separate mechanism in the same sense; termination generally occurs downstream of promoters and can be either Rho-dependent or intrinsic. Therefore, the mechanism that requires the Rho protein is the Rho-dependent termination.

The main concept is how transcription ends in bacteria and the specific role of the Rho protein. Rho-dependent termination needs a protein factor, Rho, to function. Rho binds to a rut site on the newly made RNA and uses ATP to move along the transcript toward the RNA polymerase. When it catches up to a paused polymerase, Rho disrupts the RNA–DNA hybrid and releases the RNA, terminating transcription.

In contrast, intrinsic (Rho-independent) termination doesn’t require any protein. It relies on the RNA forming a strong hairpin followed by a string of uracils, which causes the polymerase to pause and dissociate on its own.

Promoter-associated termination isn’t a separate mechanism in the same sense; termination generally occurs downstream of promoters and can be either Rho-dependent or intrinsic. Therefore, the mechanism that requires the Rho protein is the Rho-dependent termination.