Engineering bio-brick protein scaffolds for organizing enzyme assemblies.

Area of Science:

• Biochemistry
• Protein Engineering
• Synthetic Biology

Background:

• Enzyme scaffolding enhances multi-enzymatic cascade efficiency through spatial organization.
• Controlling enzyme stoichiometry is crucial for optimizing reaction rates.

Purpose of the Study:

• To introduce a novel family of engineered protein scaffolds, SCAffolding Bricks (SCABs), based on the consensus tetratricopeptide repeat (CTPR) domain.
• To develop and compare two distinct SCAB-based assembly strategies: covalent disulfide bonding and metal-driven non-covalent interactions.
• To demonstrate the efficacy of SCABs in enhancing enzymatic cascade performance.

Main Methods:

• Engineered SCAB modules utilizing CTPR domains were designed.
• Two assembly mechanisms were implemented: reversible covalent disulfide bonds and metal-coordinating interfaces.
• Enzymes, formate dehydrogenase (FDH) and L-alanine dehydrogenase (AlaDH), were genetically fused to SCAB modules.
• SCAB system assembly was triggered by specific environmental cues (non-reducing conditions or metal ions).

Main Results:

• A 3.6-fold increase in specific productivity was achieved with the SCAB system compared to free enzymes.
• Covalent disulfide-mediated SCAB assembly demonstrated superior performance over metal-driven assembly.
• Enhanced NADH cofactor regeneration and higher-order supramolecular assembly contributed to cascade efficiency.

Conclusions:

• Engineered SCABs provide a versatile platform for supramolecular organization of enzymes.
• Protein engineering of scaffolds is a powerful tool for designing efficient enzymatic cascade reactions.
• SCAB technology offers a promising strategy for improving biocatalysis and synthetic biology applications.