Oxidative desulfurization pathway for complete catabolism of sulfoquinovose by bacteria
Mahima Sharma, James P. Lingford, Marija Petricevic, Alexander Snow, Yunyang Zhang, Michael Järvå, Janice W.-Y. Mui, Nichollas E. Scott, Eleanor Saunders, Runyu Mao, Ruwan Epa, Bruna Silva, Douglas E. V. Pires, David B. Ascher, Malcolm J. McConville, G.J. Davies, Spencer J. Williams, Ethan D. Goddard‐Borger
Abstract
SQ or its glycoside sulfoquinovosyl glycerol are imported into the cell by an ATP-binding cassette transporter system with an associated SQ binding protein. A sulfoquinovosidase hydrolyzes the SQ glycoside and the liberated SQ is acted on by a flavin mononucleotide-dependent sulfoquinovose monooxygenase, in concert with an NADH-dependent flavin reductase, to release sulfite and 6-oxo-glucose. An NAD(P)H-dependent oxidoreductase reduces the 6-oxo-glucose to glucose, enabling entry into primary metabolic pathways. Structural and biochemical studies provide detailed insights into the recognition of key metabolites by proteins in this pathway. Bioinformatic analyses reveal that the sulfoquinovose monooxygenase pathway is distributed across Alpha- and Betaproteobacteria and is especially prevalent within the Rhizobiales order. This strategy for SQ catabolism is distinct from previously described pathways because it enables the complete utilization of all carbons within SQ by a single organism with concomitant production of inorganic sulfite.