Enhance the methane catalysis rates in Methylosinus trichosporium OB3b

Author: Dipayan Samanta, Department of Chemical and Biological Engineering

Mentor: Dr. Rajesh Sani, Department of Chemical and Biological Engineering

The particulate methane monooxygenase (pMMO), a membrane-bound enzyme having three-subunits (α, β, and γ) and copper-containing centers, is found in most of the methanotrophs that selectively catalyzes the oxidation of methane into methanol. Active sites in pMMO of Methylosinus trichosporium OB3b were determined by docking the modeled structure with nicotinamide adenine dinucleotide phosphate (NAD(P)H), duroquinol, 1,3-dibutadiene, and trichloroethylene. The docking energies between the modeled pMMO structure with nicotinamide adenine dinucleotide phosphate, duroquinol, 1,3-dibutadiene, and trichloroethylene were -9.7, -7.2, -4.2, and -3.8 kcal/mol, respectively, suggesting the existence of more than one active site within the monomeric subunits. The evaluation of tunnels and cavities of the active sites and the docking results showed that each active site is specific to the radius of the substrate. To increase the catalysis rates of methane in pMMO of M. trichosporium OB3b, selected amino acid residues interacting at the binding site of NAD(P)H were mutated. Based on the strain energy, docking energy and physiochemical properties, four mutants D58E, N97H, D187S, and Q272W, showed higher highest docking energies (-10, -10.4, -10.2, and -10.4 kcal/mol, respectively) than wild type (-9.7 kcal/mol) with NAD(P)HP. These results suggest that D58E, N97H, D187S, and Q272W mutations would likely increase methane oxidation rates compared to wild type.