Initial Characterization of DszA, a Monooxygenase from the Rhodococcus Biodesulfurization Pathway

Abstract

Sulfur dioxide is a pollutant found in our atmosphere that affects our health, environment, and economy. The most common source of sulfur dioxide pollution is the combustion of fossil fuels. To control pollution, it is important to remove sulfur from these fuels. The current sulfur removal method, hydrodesulfurization, is inefficient because it cannot remove sulfur from refractory organosulfur compounds. There are multiple bacterial species, including Rhodococcus erythropolis, that can remove sulfur from aromatic compounds, such as dibenzothiophene (DBT). DBT is a major organosulfur compound found in crude petroleum. The biodesulfurization pathway in Rhodococcus erythropolis can successfully remove sulfur from DBT to produce hydroxybiphenyl and sulfite. Our study focuses on an enzyme in this biodesulfurization pathway, the DBT sulfone monooxygenase, DszA that catalyzes the conversion of DBT sulfone to 2′‐hydroxybiphenyl 2‐sulfinate. Our goal was to obtain pure, active, and soluble protein for initial characterization of DszA. Thus far, we have determined the optimal parameters for expression of DszA by various expression and pH trials. The optimal temperature and pH for enzyme expression were 18°C and 7.5, respectively. DszA was successfully overexpressed in Escherichia coli and will be ready to purify by nickel affinity chromatography to take advantage of the His tag found in our protein. Our future steps are to apply steady‐state and transient‐kinetics to determine the kinetic parameters and study the mechanism of this important reaction step in the Rhodococcus biodesulfurization pathway. We will also analyze the substrate and product by high‐performance liquid chromatography to determine substrate specificity. These initial studies will provide a greater understanding towards the biodesulfurization mechanism for industrial purposes and pollution control.Support or Funding InformationThis research was supported by the Research Corporation (CCSA 22672) and by the National Institutes of Health (NIH) Grant 5SC2AI109500.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.