Related Experiment Video
Updated: Apr 23, 2026
07:58
Laboratory Techniques Used to Maintain and Differentiate Biotypes of Vibrio cholerae Clinical and Environmental Isolates
Published on: May 30, 2017
10.4K
RNA thermometer controls temperature-dependent virulence factor expression in Vibrio cholerae.
Gregor G Weber1, Jens Kortmann2, Franz Narberhaus2
1South Texas Center for Emerging Infectious Diseases and Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249; and.
Summary
A novel RNA thermometer regulates Vibrio cholerae virulence. This temperature-sensitive mechanism controls the expression of key toxins and pili, essential for cholera disease development in the human intestine.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Vibrio cholerae causes cholera, a diarrheal disease.
- Bacterial virulence factors cholera toxin (CT) and toxin-coregulated pilus (TCP) are crucial for disease.
- Expression of CT and TCP is regulated by the transcriptional activator ToxT.
Purpose of the Study:
- To identify the regulatory mechanism controlling ToxT expression in response to temperature changes.
- To investigate the role of an RNA thermometer in the 5' UTR of toxT mRNA.
- To determine the impact of this regulatory mechanism on V. cholerae virulence.
Main Methods:
- RNA probing experiments to assess RNA-DNA interactions.
- Site-directed mutagenesis to alter the RNA thermometer motif.
- Reporter assays in E. coli and V. cholerae to measure ToxT translation.
- In vivo colonization studies in infant mice.
Main Results:
- An RNA thermometer with a fourU anti-Shine-Dalgarno (SD) element was identified in the toxT 5' UTR.
- This element regulates ribosome access to the SD sequence, allowing ToxT translation at 37 °C but not 20 °C.
- Mutations strengthening base-pairing (U5C, U7C) abolished ToxT translation even at 37 °C.
- V. cholerae with the mutated UTR failed to colonize the infant mouse intestine.
Conclusions:
- A temperature-dependent RNA thermometer controls toxT translation, a key virulence regulator.
- This mechanism facilitates V. cholerae virulence in the human intestine by sensing temperature shifts.
- The identified RNA thermometer represents a novel regulatory pathway for bacterial pathogenesis.
Related Concept Videos
01:28Regulation of Bacterial Virulence
70
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
70
01:25Cholera
133
Cholera is an acute gastrointestinal disease caused by the Gram-negative bacterium Vibrio cholerae. It is transmitted primarily via the fecal-oral route through the ingestion of contaminated water or food.Vibrio cholerae is a motile, Gram-negative bacterium of the family Vibrionaceae, primarily associated with waterborne outbreaks in areas with inadequate sanitation. Although over 200 serogroups of V. cholerae exist, only O1 and O139 are responsible for epidemic cholera. The O1 serogroup,...
133
01:23Physical Methods for Controlling Microbial Growth: Temperature
1.6K
Heat is a widely used method to control microbial growth by targeting and denaturing cellular proteins, thereby killing or inactivating microbes. This method's effectiveness is quantified using parameters such as the thermal death point (TDP), thermal death time (TDT), and decimal reduction time (D value). TDP represents the lowest temperature at which all microorganisms in a liquid suspension are eliminated within 10 minutes, whereas TDT is the time necessary to achieve sterilization at a...
1.6K
01:23Stringent Response in E. coli
514
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
514
01:27Factors Influencing Microbial Growth: Temperature
2.2K
Microorganisms display remarkable adaptations, enabling them to thrive in diverse ecological niches across a wide range of temperatures. Temperature profoundly influences microbial growth by affecting enzymatic activity, membrane fluidity, and other cellular processes.Each microorganism operates within a specific temperature range defined by three cardinal points: minimum, optimum, and maximum. Below the minimum temperature, membranes lose fluidity, halting transport processes. Above the...
2.2K
01:21Hyperthermophilic Bacteria
779
Domain Bacteria includes some unique hyperthermophilic species. They exhibit remarkable adaptations that enable survival in extreme environments.Thermotoga species are rod-shaped, gram-negative, non-sporulating hyperthermophiles that form a sheath-like envelope called a toga. They ferment sugars or starch, producing lactate, acetate, CO₂, and H₂, and can also grow via anaerobic respiration using H₂ and ferric iron. Found in hot springs and hydrothermal vents, over 20% of their...
779