Biological conversion of methane to methanol through genetic reassembly of native catalytic domains

Methane monooxygenase (MMO), which exists in particulate (pMMO) or soluble forms (sMMO) in methanotrophic bacteria, is an industrially promising enzyme that catalyses oxidation of low-reactive methane and other carbon feedstocks into methanol and their corresponding oxidation products. However, the simple, fast and high-yield production of functionally active MMO, which has so far been unsuccessful despite diverse approaches based on either native methanotroph culture or recombinant expression systems, remains a major challenge for its industrial applications. Here we developed pMMO-mimetic catalytic protein constructs by genetically encoding the beneficial reassembly of catalytic domains of pMMO on apoferritin as a biosynthetic scaffold. This approach resulted in high-yield synthesis of stable and soluble protein constructs in Escherichia coli, which successfully retain enzymatic activity for methanol production with a turnover number comparable to that of native pMMO. Methane monooxygenase (MMO)—a protein of high biotechnological interest for the selective and mild conversion of methane to methanol—lacks a high-throughput production system. Now, the authors report the efficient production of particulate MMO-mimics for catalysis in solution and hydrogels.