Mechanistic studies of the biosynthesis of 2-thiosugar: evidence for the formation of an enzyme-bound 2-ketohexose intermediate in BexX-catalyzed reaction.
The first mechanistic insight into 2-thiosugar production in an angucycline-type antibiotic, BE-7585A, is reported. d-Glucose 6-phosphate was identified as the substrate for the putative thiosugar biosynthetic protein, BexX, by trapping the covalently bonded enzyme-substrate intermediate. The site-specific modification at K110 residue was determined by mutagenesis studies and LC-MS/MS analysis. A key intermediate carrying a keto functionality was confirmed to exist in the enzyme-substrate complex. These results suggest that the sulfur insertion mechanism in 2-thiosugar biosynthesis shares similarities with that for thiamin biosynthesis.
Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, United States.
Eita
E
Sasaki
Hung-Wen
HW
Liu
D002384:Catalysis; D008401:Gas Chromatography-Mass Spectrometry; D019298:Glucose-6-Phosphate / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins / Q000737:chemistry*; D054330:Thiosugars / Q000737:chemistry*
D007659:Ketones; D011994:Recombinant Proteins; D054330:Thiosugars; D019298:Glucose-6-Phosphate