Gene Expression Depends on the Interplay Among Growth, Resource Biogenesis, and Nutrient Quality

Area of Science:

• Microbiology
• Systems Biology
• Molecular Biology

Background:

• Bacterial gene expression capacity is influenced by growth rate and the availability of transcriptional and translational machinery.
• The relationship between growth and cellular resources is crucial for designing genetic constructs but is complex due to their interdependence.
• Growth rate is a primary physiological parameter governing cellular resource allocation.

Purpose of the Study:

• To investigate the distinct contributions of molecular factors, growth rate, and metabolism to bacterial gene expression.
• To elucidate the mechanisms by which these factors influence the allocation and utilization of cellular resources.
• To provide insights for optimizing bioprocesses through a better understanding of bacterial physiology.

Main Methods:

• Utilizing bacterial cells grown in chemostats to study gene expression under controlled conditions.
• Developing and experimentally validating a whole-cell model to analyze the interplay of physiological parameters.
• Analyzing the impact of molecular factors (e.g., rRNA operon copy number) and metabolic activity on gene expression.

Main Results:

• Growth rate and molecular factors determine the abundance of transcriptional and translational machinery.
• Metabolism plays a key role in regulating resource utilization by modulating elongation rates.
• Bacterial gene expression capacity can be maximized by employing low growth rates in nutrient-rich media.

Conclusions:

• Fundamental physiological trade-offs exist between growth rate, molecular machinery, and metabolic activity in bacteria.
• Metabolism is a critical determinant of resource usage efficiency, impacting overall gene expression capacity.
• These findings offer a basis for optimizing bioprocesses by manipulating growth conditions and metabolic states.