Comparative Proteomic Analysis of Propane Metabolism in Mycobacterium sp. Strain ENV421 and Rhodococcus sp. Strain ENV425.

While growing on propane as a sole source of carbon, many strains cometabolically degrade environmental pollutants, such as ethers and chlorinated hydrocarbons. To gain insights into the molecular basis behind such a high metabolic versatility of propanotrophs, we examined the propane-inducible protein expression patterns of 2 soil actinobacteria that are known to degrade a variety of ethers (i.e., Mycobacterium sp. strain ENV421 and Rhodococcus sp. strain ENV425). In both strains, soluble diiron monooxygenase(s), that would catalyze the first step of the pathway, were induced by propane. However, despite their phylogenetic similarity, different sets of additional putative propane oxygenases (e.g., cytochrome P450 and particulate methane monooxygenases) were overexpressed in the 2 strains. They also diverged in the expression of enzymes responsible for downstream reactions. This study revealed a diversity of expression of putative propane oxygenases, which may be responsible for xenobiotic degradation, as well as a variety of metabolic pathways for propane in these bacterial species.