title: S-bacillithiolation protects conserved and essential proteins against hypochlorite stress in firmicutes bacteria.
abstract: OBJECTIVE
  Protein S-bacillithiolations are mixed disulfides between protein thiols and the bacillithiol (BSH) redox buffer that occur in response to NaOCl in Bacillus subtilis. We used BSH-specific immunoblots, shotgun liquid chromatography (LC)-tandem mass spectrometry (MS/MS) analysis and redox proteomics to characterize the S-bacillithiolomes of B. subtilis, B. megaterium, B. pumilus, B. amyloliquefaciens, and Staphylococcus carnosus and also measured the BSH/oxidized bacillithiol disulfide (BSSB) redox ratio after NaOCl stress.
  
  
  RESULTS
  In total, 54 proteins with characteristic S-bacillithiolation (SSB) sites were identified, including 29 unique proteins and eight proteins conserved in two or more of these bacteria. The methionine synthase MetE is the most abundant S-bacillithiolated protein in Bacillus species after NaOCl exposure. Further, S-bacillithiolated proteins include the translation elongation factor EF-Tu and aminoacyl-tRNA synthetases (ThrS), the DnaK and GrpE chaperones, the two-Cys peroxiredoxin YkuU, the ferredoxin-NADP(+) oxidoreductase YumC, the inorganic pyrophosphatase PpaC, the inosine-5'-monophosphate dehydrogenase GuaB, proteins involved in thiamine biosynthesis (ThiG and ThiM), queuosine biosynthesis (QueF), biosynthesis of aromatic amino acids (AroA and AroE), serine (SerA), branched-chain amino acids (YwaA), and homocysteine (LuxS and MetI). The thioredoxin-like proteins, YphP and YtxJ, are S-bacillithiolated at their active sites, suggesting a function in the de-bacillithiolation process. S-bacillithiolation is accompanied by a two-fold increase in the BSSB level and a decrease in the BSH/BSSB redox ratio in B. subtilis.
  
  
  METHODS
  Many essential and conserved proteins, including the dominant MetE, were identified in the S-bacillithiolome of different Bacillus species and S. carnosus using shotgun-LC-MS/MS analyses.
  
  
  CONCLUSIONS
  S-bacillithiolation is a widespread redox control mechanism among Firmicutes bacteria that protects conserved metabolic enzymes and essential proteins against overoxidation.
authors.affiliation: Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, Greifswald, Germany.
authors.forename: Bui Khanh
authors.initials: BK
authors.lastname: Chi
authors.forename: Alexandra A
authors.initials: AA
authors.lastname: Roberts
authors.forename: Tran Thi Thanh
authors.initials: TT
authors.lastname: Huyen
authors.forename: Katrin
authors.initials: K
authors.lastname: Bäsell
authors.forename: Dörte
authors.initials: D
authors.lastname: Becher
authors.forename: Dirk
authors.initials: D
authors.lastname: Albrecht
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Hamilton
authors.forename: Haike
authors.initials: H
authors.lastname: Antelmann
mesh_terms: D001407:Bacillus / Q000187:drug effects / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D053898:Biosynthetic Pathways; D003545:Cysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D006997:Hypochlorous Acid / Q000378:metabolism*; D055432:Metabolomics; D008780:Methyltransferases / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D020543:Proteome / Q000378:metabolism; D040901:Proteomics; D012973:Sodium Hypochlorite / Q000378:metabolism / Q000494:pharmacology; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; C543521:bacillithiol; D006997:Hypochlorous Acid; D012973:Sodium Hypochlorite; D008780:Methyltransferases; D003545:Cysteine; D005944:Glucosamine