What role does the Rho factor play in Rho-dependent termination?

The Rho factor is a key protein involved in the process of Rho-dependent termination of transcription in prokaryotic cells. Its primary function is to recognize and bind to specific sequences on the newly synthesized RNA molecule, particularly at a site known as the rut (Rho utilization) site.

Once Rho binds to the RNA at the rut site, it utilizes its helicase activity to move along the RNA strand towards the RNA polymerase complex. This movement helps in displacing the RNA polymerase from the DNA template after it has finished synthesizing the RNA transcript. The termination of transcription facilitated by Rho is essential for the proper regulation of gene expression, ensuring that RNA polymerase stops transcription at the correct point and that the RNA molecule produced is of the appropriate length.

In contrast, the other options describe functions that are not associated with Rho's role in termination. For instance, Rho does not initiate RNA synthesis, nor does it promote DNA replication or stabilize RNA polymerase directly. Instead, its interaction with specific RNA sequences is critical for effectively terminating transcription. Thus, the correct choice emphasizes the specific interaction of Rho with the RNA at the rut site, which is fundamental to the termination process.