FAD binding and dissociation in GMC-oxidoreductases.

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• The glucose-methanol-choline (GMC)-oxidoreductase superfamily includes key flavoenzymes like glucose oxidase.
• Recombinant flavoenzyme applications are limited by glycosylation and FAD occupancy issues.

Purpose of the Study:

• To structurally analyze FAD deflavination and reconstitution in three GMC-oxidoreductases.
• To investigate the role of glycosylation in flavoenzyme stability and FAD binding.

Main Methods:

• Experimental determination of FAD dissociation constants (K_d).
• Analysis of thermal stability with and without FAD/N-glycosides.
• Steered molecular dynamics simulations to probe FAD binding and dissociation pathways.

Main Results:

• Glycosylation levels critically affect FAD deflavination and reconstitution.
• FAD dissociation constants range from 10 to 47 nM for the studied enzymes.
• FAD and N-glycosides enhance flavoenzyme thermal stability.
• A novel FAD dissociation route involving a loop-and-lid structure was identified.

Conclusions:

• Glycosylation is crucial for flavoenzyme FAD binding and stability.
• Insights into FAD dissociation mechanisms offer strategies for optimizing recombinant flavoenzyme production.
• The findings advance the understanding of GMC-oxidoreductase function and engineering.