key term - Rho-dependent termination

Definition

Rho-dependent termination is a mechanism of transcription termination in bacteria where the Rho protein acts as a helicase to disrupt the RNA-DNA hybrid, causing the RNA polymerase to dissociate from the DNA template and release the newly synthesized RNA transcript.

5 Must Know Facts For Your Next Test

1. Rho-dependent termination occurs when the Rho protein binds to specific Rho-utilization (Rut) sites on the nascent RNA transcript and tracks along the RNA, eventually catching up to the RNA polymerase.
2. The Rho protein uses its ATP-dependent helicase activity to disrupt the RNA-DNA hybrid, causing the RNA polymerase to release the transcript and dissociate from the DNA template.
3. Rho-dependent termination is an important mechanism for controlling gene expression in bacteria, allowing the cell to regulate the production of specific mRNAs.
4. The efficiency of Rho-dependent termination can be influenced by factors such as the strength of the Rut site, the rate of Rho binding and translocation, and the stability of the RNA-DNA hybrid.
5. Rho-dependent termination is distinct from Rho-independent (or intrinsic) termination, which relies on the formation of a stable RNA hairpin structure to signal the end of transcription.

Review Questions

• Describe the role of the Rho protein in the process of Rho-dependent termination.
  • The Rho protein is a key player in Rho-dependent termination. It acts as a helicase, binding to specific Rho-utilization (Rut) sites on the nascent RNA transcript and then tracking along the RNA until it catches up to the RNA polymerase. Once the Rho protein reaches the RNA polymerase, it uses its ATP-dependent helicase activity to disrupt the RNA-DNA hybrid, causing the RNA polymerase to release the transcript and dissociate from the DNA template. This Rho-dependent termination mechanism allows the cell to regulate gene expression by controlling the production of specific mRNAs.
• Explain how Rho-dependent termination differs from Rho-independent (intrinsic) termination.
  • Rho-dependent termination and Rho-independent (or intrinsic) termination are two distinct mechanisms of transcription termination in bacteria. Rho-dependent termination relies on the Rho protein, which acts as a helicase to disrupt the RNA-DNA hybrid and release the RNA polymerase. In contrast, Rho-independent termination does not require the Rho protein and instead relies on the formation of a stable RNA hairpin structure that signals the end of transcription. The efficiency of each termination mechanism can be influenced by different factors, such as the strength of the Rut site (for Rho-dependent) or the stability of the RNA hairpin (for Rho-independent).
• Analyze the importance of Rho-dependent termination in the regulation of gene expression in bacteria.
  • Rho-dependent termination is a crucial mechanism for the regulation of gene expression in bacteria. By allowing the cell to control the production of specific mRNAs, Rho-dependent termination provides a means of fine-tuning the expression of genes in response to changing environmental conditions or developmental cues. This regulatory control is important for the efficient allocation of cellular resources, as well as for the coordinated expression of genes involved in various cellular processes. The ability of the Rho protein to respond to different Rho-utilization (Rut) sites and the influence of factors like Rut site strength and RNA-DNA hybrid stability on termination efficiency further underscores the versatility and importance of Rho-dependent termination in bacterial gene regulation.

Related terms

Rho protein: A hexameric protein that acts as a transcription termination factor in bacteria, using its helicase activity to disrupt the RNA-DNA hybrid and release the RNA polymerase.

RNA-DNA hybrid: The double-stranded structure formed by the newly synthesized RNA transcript and the DNA template during transcription.

Transcription termination: The process by which RNA polymerase disengages from the DNA template, releasing the completed RNA transcript.