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Bacterial flavoprotein monooxygenase YxeK salvages toxic S-(2-succino)-adducts via oxygenolytic C-S bond cleavage.

Arne MatthewsJulia SchönfelderSimon LagiesErik SchleicherBernd KammererHolly R EllisFrederick StullRobin Teufel
Published in: The FEBS journal (2021)
Thiol-containing nucleophiles such as cysteine react spontaneously with the citric acid cycle intermediate fumarate to form S-(2-succino)-adducts. In Bacillus subtilis, a salvaging pathway encoded by the yxe operon has recently been identified for the detoxification and exploitation of these compounds as sulfur sources. This route involves acetylation of S-(2-succino)cysteine to N-acetyl-2-succinocysteine, which is presumably converted to oxaloacetate and N-acetylcysteine, before a final deacetylation step affords cysteine. The critical oxidative cleavage of the C-S bond of N-acetyl-S-(2-succino)cysteine was proposed to depend on the predicted flavoprotein monooxygenase YxeK. Here, we characterize YxeK and verify its role in S-(2-succino)-adduct detoxification and sulfur metabolism. Detailed biochemical and mechanistic investigation of YxeK including 18 O-isotope-labeling experiments, homology modeling, substrate specificity tests, site-directed mutagenesis, and (pre-)steady-state kinetics provides insight into the enzyme's mechanism of action, which may involve a noncanonical flavin-N5-peroxide species for C-S bond oxygenolysis.
Keyphrases
  • fluorescent probe
  • bacillus subtilis
  • living cells
  • dna binding
  • crispr cas
  • drinking water
  • transition metal
  • high resolution
  • transcription factor
  • histone deacetylase
  • simultaneous determination