Horizontal gene transfer of copper-containing membrane-bound monooxygenase (CuMMO) and di-iron soluble monooxygenase (SDIMO) in ethane- and propane-oxidizing Rhodococcus.

The families of copper-containing membrane-bound monooxygenases (CuMMOs) and soluble di-iron monooxygenases (SDIMOs) are not only involved in methane oxidation but also in short-chain alkane oxidation. Herein, we describe Rhodococcus sp. ZPP, a bacterium able to grow with ethane or propane as the sole carbon and energy source and report on horizontal gene transfer (HGT) of actinobacterial hydrocarbon monooxygenases (HMO) of the CuMMO family and sMMO (soluble methane monooxygenase)-like SDIMO in the genus Rhodococcus The key function of HMO in strain ZPP for propane oxidation was verified by allylthiourea inhibition. The HMO genes (designated hmoCAB) and those encoding sMMO-like SDIMO (designated smoXYB1C1Z) are located on a linear mega-plasmid (pRZP1) of strain ZPP. Comparative genomic analysis of similar plasmids indicated mobility of these plasmids within the genus Rhodococcus The plasmid pRZP1 in strain ZPP could be conjugatively transferred to a recipient R. erythropolis in a mating experiment and showed similar ethane and propane consuming activities. Finally, our findings demonstrate that horizontal transfer of plasmid-based CuMMO and SDIMO genes confers the ability to use ethane and propane on the recipient.ImportanceCuMMOs and SDIMOs initiate the aerobic oxidation of alkanes in bacteria. Here, the supposition that horizontally transferred plasmid-based CuMMO and SDIMO genes confer on the recipient the similar ability to use ethane and propane was proposed and confirmed in Rhodococcus. This study is a living example of HGT of CuMMOs and SDIMOs and outlines the plasmid-borne properties responsible for gaseous alkane-degradation. Our results indicate that plasmids can support rapid evolution of enzyme-mediated biogeochemical processes.