Expression and characterization of a codon-optimized alkaline-stable carbonic anhydrase from Aliivibrio salmonicida for CO2 sequestration applications

Engineering stable carbonic anhydrases for CO2 capture: a critical review

Targeted inhibition of misregulated protein-protein interactions (PPIs) has been a promising area of investigation in drug discovery and development for human diseases. However, many constraints remain, including shallow binding surfaces and dynamic conformation changes upon interaction. A particularly challenging aspect is the undesirable off-target effects caused by inherent structural similarity among the protein families. To tackle this problem, phage display has been used to engineer PPIs for high-specificity binders with improved binding affinity and greatly reduced undesirable interactions with closely related proteins. Although general steps of phage display are standardized, library design is highly variable depending on experimental contexts. Here in this review, we examined recent advances in the structure-based combinatorial library design and the advantages and limitations of different approaches. The strategies described here can be explored for other protein-protein interactions and aid in designing new libraries or improving on previous libraries.

Characterization and High-Level Periplasmic Expression of Thermostable α-Carbonic Anhydrase from Thermosulfurimonas Dismutans in Escherichia Coli for CO2 Capture and Utilization

Carbonic anhydrase (CA) is a diffusion-controlled enzyme that rapidly catalyzes carbon dioxide (CO₂) hydration. CA has been considered as a powerful and green catalyst for bioinspired CO₂ capture and utilization (CCU). For successful industrial applications, it is necessary to expand the pool of thermostable CAs to meet the stability requirement under various operational conditions. In addition, high-level expression of thermostable CA is desirable for the economical production of the enzyme. In this study, a thermostable CA (tdCA) of Thermosulfurimonas dismutans isolated from a deep-sea hydrothermal vent was expressed in Escherichia coli and characterized in terms of expression level, solubility, activity and stability. tdCA showed higher solubility, activity, and stability compared to those of CA from Thermovibrio ammonificans, one of the most thermostable CAs, under low-salt aqueous conditions. tdCA was engineered for high-level expression by the introduction of a point mutation and periplasmic expression via the Sec-dependent pathway. The combined strategy resulted in a variant showing at least an 8.3-fold higher expression level compared to that of wild-type tdCA. The E. coli cells with the periplasmic tdCA variant were also investigated as an ultra-efficient whole-cell biocatalyst. The engineered bacterium displayed an 11.9-fold higher activity compared to that of the recently reported system with a halophilic CA. Collectively these results demonstrate that the highly expressed periplasmic tdCA variant, either in an isolated form or within a whole-cell platform, is a promising biocatalyst with high activity and stability for CCU applications.