Sulfation in the Biosynthesis of the Heptadecaglycoside Antibiotic Saccharomicin A

Sulfation is a ubiquitous modification in glycobiology, yet its enzymology and biological significance in glycosylated natural products remain poorly understood. Saccharomicin A, a potent oligosaccharide antibiotic, carries 17 sugars including a unique sulfated fucose. Here, we report the identification of Sam10 as an unprecedented fucose-specific sulfotransferase through genetic studies, in vitro reconstitution, and structural analysis, establishing its role in saccharomicin sulfation. Comparative bioassays revealed that sulfation contributes to antibacterial potency, including activity against diverse multidrug-resistant pathogens. We also characterized Sam35 as an efficient adenylyl-sulfate kinase that boosts cellular 3′-phosphoadenosine-5′-phosphate sulfate (PAPS) supply. Our findings define the biochemical and structural basis of saccharomicin sulfation and provide enzymatic tools for engineering novel sulfated oligosaccharide antibiotics.