Ergothioneine is a secreted antioxidant in Mycobacterium smegmatis

Antimicrob Agents Chemother. 2013 Jul;57(7):3202-7. doi: 10.1128/AAC.02572-12. Epub 2013 Apr 29.


Ergothioneine (ERG) and mycothiol (MSH) are two low-molecular-weight thiols synthesized by mycobacteria. The role of MSH has been extensively investigated in mycobacteria; however, little is known about the role of ERG in mycobacterial physiology. In this study, quantification of ERG at various points in the growth cycle of Mycobacterium smegmatis revealed that a significant portion of ERG is found in the culture media, suggesting that it is actively secreted. A mutant of M. smegmatis lacking egtD (MSMEG_6247) was unable to synthesize ERG, confirming its role in ERG biosynthesis. Deletion of egtD from wild-type M. smegmatis and an MSH-deficient mutant did not affect their susceptibility to antibiotics tested in this study. The ERG- and MSH-deficient double mutant was significantly more sensitive to peroxide than either of the single mutants lacking either ERG or MSH, suggesting that both thiols play a role in protecting M. smegmatis against oxidative stress and that ERG is able to partly compensate for the loss of MSH.

MeSH terms

  • Antioxidants / metabolism*
  • Bacterial Proteins / metabolism
  • Culture Media
  • Cysteine / metabolism
  • Drug Resistance, Bacterial / genetics*
  • Ergothioneine / genetics
  • Ergothioneine / metabolism*
  • Glycopeptides / metabolism
  • Inositol / metabolism
  • Microbial Sensitivity Tests
  • Mutation
  • Mycobacterium smegmatis / drug effects
  • Mycobacterium smegmatis / genetics
  • Mycobacterium smegmatis / metabolism*
  • Oxidative Stress


  • Antioxidants
  • Bacterial Proteins
  • Culture Media
  • Glycopeptides
  • mycothiol
  • Inositol
  • Ergothioneine
  • Cysteine