ROS mediated selection for increased NADPH availability in Escherichia coli

Area of Science:

• Biotechnology and metabolic engineering
• Microbial chemical and fuel production

Background:

• Economical microbial production of chemicals and fuels is a key biotechnology goal.
• Limited availability of essential co-factors like nicotinamide adenine dinucleotide phosphate (NADPH) hinders metabolic pathway efficiency.
• Current strategies to increase NADPH in Escherichia coli often disrupt central metabolism, causing redox imbalances and growth defects.

Purpose of the Study:

• To discover novel methods for increasing NADPH availability in Escherichia coli.
• To investigate the impact of a specific gene mutation on NADPH levels.
• To assess the utility of enhanced NADPH for improving bioproduction.

Main Methods:

• Utilized a reactive oxygen species-based selection strategy to identify genetic targets.
• Screened for mutations that enhance NADPH availability in Escherichia coli.
• Analyzed the effect of a loss-of-function mutation in the hdfR gene.

Main Results:

• Identified a loss-of-function mutation in the hdfR gene that significantly increases NADPH availability in Escherichia coli.
• Demonstrated that the excess NADPH generated can be channeled into metabolic pathways.
• Showed improved production of 3-hydroxypropionic acid (3HP) in E. coli strains with the hdfR mutation.

Conclusions:

• The hdfR gene is a novel target for enhancing NADPH regeneration in microbial systems.
• This approach circumvents the need for central metabolism manipulation, avoiding growth defects.
• The enhanced NADPH can be effectively utilized for improving the biosynthesis of valuable chemicals like 3HP.