Dissecting host stress responses for predictable heterologous gene expression in E. coli

Area of Science:

• Biotechnology and Molecular Biology
• Systems Biology
• Microbial Physiology

Background:

• Predictable heterologous gene expression is crucial for biotechnology but hindered by host cellular stress.
• Existing research often overlooks the complex interplay of transcriptional, translational, and product-specific stresses.

Purpose of the Study:

• To systematically dissect cellular stress responses in Escherichia coli during heterologous gene expression.
• To identify distinct stress response pathways triggered by transcriptional and translational burdens.
• To develop strategies for optimizing protein production by targeting specific stress responses.

Main Methods:

• Utilized independent component analysis on large transcriptomic datasets from E. coli MG1655.
• Analyzed stress responses under varying promoters and translation efficiencies for diverse protein expression.
• Correlated transcriptomic data with known stress response pathways.

Main Results:

• Excessive heterologous messenger RNA (mRNA) induces a cold shock response affecting mRNA stability.
• Protein production activates a heat shock response involving proteolysis and chaperones.
• A broad adaptation response, including stationary phase and osmoregulation, is co-activated with heat shock.
• Strain and media modifications targeting adaptation responses significantly enhanced eGFP production.
• Cysteine-rich protein expression uniquely triggered iron, redox, and oxidative stress responses.

Conclusions:

• Cellular stress responses to heterologous gene expression are multifaceted, involving transcriptional, translational, and product-specific factors.
• Distinct stress pathways (cold shock, heat shock, adaptation) can be identified and differentiated.
• Targeting specific host adaptation mechanisms offers a promising route for enhancing biotechnological protein production.
• A systems-level understanding is essential for developing predictable and optimized gene expression strategies.