A Widespread Radical-Mediated Glycolysis Pathway.

Area of Science:

• Biochemistry and Molecular Biology
• Enzymology
• Metabolic Engineering

Background:

• Glycyl radical enzymes (GREs) are crucial for diverse radical-mediated reactions in anaerobic bacteria.
• Two GREs in Escherichia coli, YbiW and PflD, have unknown functions despite being widespread in the human gut microbiome.

Purpose of the Study:

• To elucidate the functions of YbiW and PflD in E. coli metabolism.
• To characterize the novel 'anhydroglycolysis' pathway.
• To explore the potential of this pathway for biotechnological applications, such as 1,2-propanediol production.

Main Methods:

• Enzyme activity assays to determine substrate specificity and reaction products.
• Crystal structure determination of YbiW and PflD with their substrates.
• Genetic analysis to demonstrate the physiological role of the pathway in E. coli growth.

Main Results:

• YbiW and PflD catalyze the ring-opening C-O cleavage of 1,5-anhydroglucitol-6-phosphate (AG6P) and 1,5-anhydromannitol-6-phosphate (AM6P), respectively.
• The anhydroglycolysis pathway converts these substrates into intermediates that can be further metabolized to 1,2-propanediol (1,2-PDO).
• Crystal structures reveal the mechanism of radical-mediated C-O cleavage by these GREs.

Conclusions:

• The anhydroglycolysis pathway provides a mechanism for anaerobic growth on AG and AM, clarifying the roles of YbiW, PflD, and downstream enzymes.
• This pathway expands the known catalytic capabilities of GREs.
• The pathway offers a promising route for the sustainable production of 1,2-PDO from abundant carbohydrate sources.