RNA Polymerase II Accessory Proteins
Transcription Attenuation in Prokaryotes
The Ras Gene
Bacterial Transcription
Small GTPases - Ras and Rho
Transcriptional Regulation: Riboswitches
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Updated: Jul 11, 2026

Analysis of Termination of Transcription Using BrUTP-strand-specific Transcription Run-on (TRO) Approach
Published on: March 12, 2017
This study explores how a mutant version of the rho protein, called rho1, affects transcription termination in Escherichia coli. The rho protein is essential for stopping RNA synthesis during gene expression. The researchers found that the rho1 mutant protein can interfere with the normal rho protein's function by forming hybrid structures. These hybrids disrupt the ability of wild-type rho to interact with RNA and hydrolyze ATP. The study shows that the rho1 mutant is partially dominant, meaning it can override the normal protein's activity. The mechanism involves the formation of hybrid hexamers, where mutant subunits disrupt the cooperative interactions needed for proper function. The findings suggest that subunit interactions are crucial for rho protein activity and that mutant proteins can impair normal transcription processes.
Area of Science:
Background:
Transcription termination in bacteria relies on the rho factor, a protein that interacts with RNA and ATP to regulate gene expression. Prior research has shown that rho factor functions by binding RNA and hydrolyzing ATP to facilitate termination. However, the role of mutant rho alleles in this process remains unclear. This gap motivated investigations into how specific mutations affect rho activity. The rho1 (suA1) mutant allele has been studied for its impact on transcription termination. It was already known that rho factor forms hexameric structures to perform its function. No prior work had resolved how mutant rho proteins might interfere with wild-type rho. This study addresses the mechanism of interference by a defective rho protein. Understanding these interactions helps clarify the functional requirements of rho factor in transcription termination.
Purpose Of The Study:
This study aims to determine how the rho1 mutant protein affects transcription termination and ATPase activity in Escherichia coli. The specific problem addressed is the partial dominance of the rho1 allele over wild-type rho. The motivation stems from the need to understand how mutant rho proteins interfere with normal function. The researchers propose that defective rho subunits may disrupt wild-type rho activity. The focus is on the interaction between mutant and wild-type rho proteins. The study tests whether rho1 inhibits transcription termination and ATPase activity. The goal is to identify the mechanism of this inhibition. The findings could clarify the role of subunit interactions in rho function.
Main Methods:
The researchers isolated rho protein from Escherichia coli with the rho1 (suA1) mutant allele. They tested interactions between rho1 and RNA to assess ATP hydrolysis. Transcription termination assays measured the effect of rho1 on termination efficiency. RNA-dependent ATPase activity was evaluated in the presence of rho1. Hybrid hexamers were analyzed to determine subunit exchange. The study used biochemical assays to compare wild-type and mutant rho proteins. Structural analysis of hexamers was performed to identify defective subunits. The experiments focused on how mutant rho proteins interfere with wild-type function.
Main Results:
The rho1 mutant protein shows reduced ATP hydrolysis when interacting with RNA. Transcription termination is inhibited in the presence of rho1. RNA-dependent ATPase activity is also suppressed by the mutant protein. Hybrid hexamers form when wild-type and mutant rho subunits exchange. Defective subunits in hybrid hexamers disrupt cooperative interactions. The inhibition is dose-dependent with increasing RNA concentration. Wild-type rho function is impaired by the presence of rho1. These findings suggest that subunit interactions are essential for rho activity.
Conclusions:
The rho1 mutant protein interferes with wild-type rho function by forming hybrid hexamers. This interference disrupts cooperative interactions needed for ATP hydrolysis. The mechanism of partial dominance involves subunit exchange in hexamers. The study supports the importance of subunit interactions in rho activity. No prior work had resolved how mutant rho proteins could inhibit wild-type rho. The findings suggest that defective subunits can impair overall function. The results highlight the role of RNA in modulating rho activity. These conclusions align with the observed effects on transcription termination.
The rho1 mutant protein inhibits transcription termination and RNA-dependent ATPase activity of wild-type rho.
The rho1 protein forms hybrid hexamers with wild-type rho subunits, disrupting cooperative interactions.
Excess RNA promotes subunit exchange, leading to hybrid hexamers that impair ATPase function.
Hybrid hexamers disrupt cooperative interactions essential for wild-type rho subunit function.
The rho1 mutant reduces ATP hydrolysis when interacting with RNA, impairing termination efficiency.
The study proposes that defective rho subunits interfere with wild-type function through hybrid hexamer formation.