A Two-Enzyme Adaptive Unit within Bacterial Folate Metabolism

Area of Science:

• Biochemistry
• Evolutionary Biology
• Genomics

Background:

• Enzyme function is shaped by metabolic pathways.
• Compensatory mutations can arise in interacting enzymes.
• Dihydrofolate reductase (DHFR) is an essential metabolic enzyme.

Purpose of the Study:

• To investigate the evolutionary interactions of DHFR within metabolic pathways.
• To determine if DHFR and thymidylate synthase (TYMS) co-evolve.
• To understand how these enzymes adapt to environmental stress.

Main Methods:

• Comparative genomics (synteny and co-occurrence analysis).
• Experimental evolution using Escherichia coli.
• Quantitative growth rate measurements.
• Metabolomic profiling.

Main Results:

• DHFR and TYMS exhibit coupled evolution, acting as a distinct module.
• This DHFR-TYMS module adapts independently under antibiotic stress.
• Maintaining a balance between TYMS and DHFR activity prevents metabolic disruption.

Conclusions:

• Cellular metabolic pathways can be decomposed into co-evolving adaptive modules.
• The DHFR-TYMS module represents a significant unit of adaptation in bacteria.
• Comparative genomics can identify such modular evolutionary patterns across >200 gene pairs.