Rho-dependent termination and concomitant NTPase activity requires a specific, intact RNA region

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Rho-dependent transcription termination is a crucial process regulating gene expression in bacteria.
• The precise molecular requirements for rho-mediated termination, particularly the roles of DNA and RNA, remain incompletely understood.

Purpose of the Study:

• To investigate the specific DNA and RNA requirements for rho-dependent transcription termination in vitro.
• To elucidate the role of the Escherichia coli trp operon terminator (trp t') in this process.

Main Methods:

• In vitro transcription assays using templates containing the trp t' terminator.
• Analysis of rho-dependent termination and rho NTPase activity.
• Treatment with ribonuclease T1 to assess RNA's role.

Main Results:

• Templates with the trp t' region specifically directed rho-dependent termination and stimulated rho NTPase activity.
• Deletion of the trp t' region abolished termination and NTPase activity.
• Ribonuclease T1 treatment eliminated termination and NTPase activity, highlighting RNA's necessity.
• Rho NTPase activation did not require active transcription, as RNA components alone could activate it.

Conclusions:

• A specific RNA component within the trp t' transcript is essential for rho NTPase activation and rho-dependent transcription termination.
• The low guanine content in the trp t' region may reduce RNA secondary structure, facilitating termination.
• These findings contribute to understanding the mechanisms governing rho-dependent transcription termination, despite a lack of conserved sequence homology at termination sites.