Oxygenolytic sulfoquinovose degradation by an iron-dependent alkanesulfonate dioxygenase

Sulfoquinovose (6-deoxy-6-sulfo-D-glucose, SQ), the polar head group of sulfolipids in plants, is abundant in nature. Many bacteria degrade SQ through pathways termed sulfoglycolysis producing C3 or C2 sulfonates, while certain bacteria degrade SQ through direct oxygenolytic cleavage of the SQ C-S bond, cata-lyzed by a flavin-dependent alkanesulfonate monooxygenase (sulfo-ASMO pathway). Here we report bio-informatics and biochemical studies revealing an alternative mechanism for oxygenolytic cleavage of the SQ C-S bond, catalyzed by an iron and alpha-ketoglutarate-dependent alkanesulfonate dioxygenase (SqoD, sulfo-ASDO pathway). In both the ASMO and ASDO pathways, the product 6-dehydroglucose is reduced to glucose by NAD(P)H-dependent SquF. Marinomonas ushuaiensis, a marine bacterium, which harbors the sulfo-ASDO gene cluster is shown utilizing SQ as a carbon source for growth, accompanied by increased transcription of SqoD. The sulfo-ASDO pathway highlights the range of microbial strategies for degradation of this ubiquitous sulfo-sugar, with potential implications for sulfur recycling in different biological environments.

Automated summary

This study reports an alternative mechanism for the oxygenolytic cleavage of sulfoquinovose (SQ) catalyzed by an iron and alpha-ketoglutarate-dependent alkanesulfonate dioxygenase (SqoD, sulfo-ASDO pathway). The marine bacterium Marinomonas ushuaiensis utilizes SQ as a carbon source through the sulfo-ASDO pathway, suggesting potential implications for sulfur recycling in different biological environments.