Genetically structured mathematical modeling of trp attenuator mechanism

Area of Science:

• Molecular Biology
• Systems Biology
• Microbial Genetics

Background:

• The trp operon in Escherichia coli is regulated by both attenuation and repressor mechanisms.
• Understanding the interplay between transcription and translation in gene regulation is crucial.

Purpose of the Study:

• To develop a genetically structured mathematical model of the trp attenuator in Escherichia coli.
• To simulate and quantify the effects of tryptophan concentration on gene product repression.
• To compare the regulatory range of the attenuation and repressor mechanisms.

Main Methods:

• Development of a mathematical model integrating transcription and translation coupling.
• Simulation of Escherichia coli trp attenuator function under varying tryptophan levels.
• Quantitative analysis of repression effects on cloned gene products.

Main Results:

• The trp attenuator operates effectively within a narrow tryptophan concentration range (1-5 microM).
• Attenuation derepression is observed only when the repressor is significantly less repressed (below 20%).
• The attenuator's operating range is independent of plasmid copy number, unlike repressor-operator interactions.

Conclusions:

• The attenuation mechanism provides fine-tuning of gene expression under specific tryptophan limitations.
• Severe tryptophan starvation is required to overcome attenuation-based repression.
• The model provides insights into the distinct roles and sensitivities of the two trp operon regulatory systems.