Mechanism for sulfur acquisition by the alkanesulfonate monooxygenase system

The bacterial alkanesulfonate monooxygenase system is involved in the acquisition of sulfur from organosulfonated compounds during limiting sulfur conditions. The reaction relies on an FMN reductase to supply reduced flavin to the monooxygenase enzyme. The reaction catalyzed by the alkanesulfonate monooxygenase enzyme involves the carbon–sulfur bond cleavage of a wide range of organosulfonated compounds. A C4a-(hydro)peroxyflavin is the oxygenating intermediate in the mechanism of desulfonation by the alkanesulfonate monooxygenase. This review discusses the physiological importance of this system, and the individual kinetic parameters and mechanistic properties of this enzyme system.

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► In this review we examine the mechanism of the alkanesulfonate monooxygenase system.
► Flavin reduction by SsuE follows an order sequential mechanism.
► The SsuE mechanism is altered in the presence of SsuD and octanesulfonate.
► A C4a-(hydro)peroxyflavin is the oxygenating flavin intermediate in the SsuD reaction.
► Two mechanistic strategies for desulfonation by SsuD are described.