Protective Role of Bacterial Alkanesulfonate Monooxygenase under Oxidative Stress.

Bacterial alkane metabolism is associated with a number of cellular stresses, including membrane stress and oxidative stress, and the limited uptake of charged ions such as sulfate. In the present study, the genes and in DR1 cells, which encode an alkanesulfonate monooxygenase and a taurine dioxygenase, respectively, were found to be responsible for hexadecanesulfonate (CSOH) and taurine metabolism, and Cbl was experimentally identified as a potential regulator of and expression. The expression of and occurred under sulfate-limited conditions generated during -hexadecane degradation. Interestingly, expression analysis and knockout experiments suggested that both genes are required to protect cells against oxidative stress, including that generated by -hexadecane degradation and HO exposure. Measurable levels of intracellular hexadecanesulfonate were also produced during -hexadecane degradation. Phylogenetic analysis suggested that and are mainly present in soil-dwelling aerobes within the and classes, which suggests that they function as controllers of the sulfur cycle and play a protective role against oxidative stress in sulfur-limited conditions. and , which play a role in the degradation of organosulfonate, were expressed during -hexadecane metabolism and oxidative stress conditions in DR1. Our study confirmed that hexadecanesulfonate was accidentally generated during bacterial -hexadecane degradation in sulfate-limited conditions. Removal of this by-product by SsuD and TauD must be necessary for bacterial survival under oxidative stress generated during -hexadecane degradation.

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