In-cell engineering can be a powerful tool for synthesizing functional protein crystals with promising catalytic properties, show researchers at Tokyo Tech. Using genetically modified bacteria as an environmentally friendly synthesis platform, the researchers produced hybrid solid catalysts for artificial photosynthesis. These catalysts exhibit high activity, stability, and durability, highlighting the potential of the proposed innovative approach.
Newswise — According to researchers at Tokyo Tech, in-cell engineering offers a powerful means of creating functional protein crystals with highly promising catalytic properties. By utilizing genetically modified bacteria as an eco-friendly synthesis platform, these scientists successfully developed hybrid solid catalysts for artificial photosynthesis. These catalysts demonstrate exceptional activity, stability, and durability, underscoring the immense potential of this groundbreaking approach.
Protein crystals, akin to traditional crystals, boast well-organized molecular structures with a wide range of properties, presenting significant opportunities for customization. What sets them apart is their natural ability to self-assemble using cellular materials, leading to reduced synthesis costs and a more environmentally friendly production process.
While protein crystals hold great potential as catalysts due to their ability to host various functional molecules, current techniques are limited to attaching only small molecules and simple proteins. Therefore, the crucial challenge lies in discovering methods to create protein crystals that can carry both natural enzymes and synthetic functional molecules, fully harnessing their capabilities for enzyme immobilization.
In a significant breakthrough, researchers from Tokyo Institute of Technology (Tokyo Tech), led by Professor Takafumi Ueno, have devised an innovative approach to create hybrid solid catalysts using protein crystals. Their research, published in Nano Letters on 12 July 2023, merges in-cell engineering with a simple in vitro process to fabricate catalysts designed for artificial photosynthesis.
At the core of this hybrid catalyst lies a protein monomer obtained from a virus that typically infects the Bombyx mori silkworm. By introducing the gene responsible for this protein into Escherichia coli bacteria, the researchers prompted the production of monomers that aggregated into trimers. These trimer units then spontaneously organized themselves into stable polyhedra crystals (PhCs) by binding through their N-terminal α-helix (H1). Additionally, the team incorporated a modified version of the formate dehydrogenase (FDH) gene from a specific yeast species into the E. coli genome. This gene alteration led the bacteria to generate FDH enzymes with H1 terminals, thereby facilitating the formation of hybrid H1-FDH@PhC crystals within the cells.
The team utilized sonication and gradient centrifugation to extract the hybrid crystals from the E. coli bacteria. Subsequently, these crystals were immersed in a solution containing the artificial photosensitizer eosin Y (EY). The genetically modified protein monomers, featuring a modified central channel to accommodate EY molecules, facilitated a stable and abundant binding of EY to the hybrid crystals.
This innovative process resulted in the creation of remarkably active, recyclable, and thermally stable EY·H1-FDH@PhC catalysts. These catalysts, when exposed to light, could efficiently convert carbon dioxide (CO2) into formate (HCOO−), akin to the process of photosynthesis. Impressively, even after immobilization, the hybrid crystals retained 94.4% of their catalytic activity compared to that of the free enzyme. Professor Ueno emphasized that the conversion efficiency of their hybrid crystal surpassed previously reported compounds for enzymatic artificial photosynthesis based on FDH. Furthermore, the hybrid PhC maintained its solid protein assembly state, demonstrating the exceptional crystallizing capacity and robust plasticity of PhCs as encapsulating scaffolds, following both in vivo and in vitro engineering processes.
This study underscores the enormous potential of bioengineering in synthesizing intricate functional materials. Professor Ueno concludes that the combination of in vivo and in vitro techniques for encapsulating protein crystals offers a promising and environmentally friendly strategy for advancements in nanomaterials and artificial photosynthesis research.
Overall, these efforts hold the promise of steering us towards a more sustainable and eco-friendly future!
RSS