Glutathione is a host-derived cysteine source for Clostridioides difficile

In the gastrointestinal (GI) tract, C. difficile must acquire essential nutrients to colonize, establish infection, and persists in a polymicrobial environment. C. difficile is a cysteine auxotroph and the GI tract contains low levels of cysteine, highlighting gaps in our understanding of how C. difficile acquires this amino acid during infection.

One possible source of cysteine for C. difficile during infection is glutathione (GSH), tripeptide thiol in mammalian cells. Our data indicate that C. difficile encodes two redundant enzymes (GecA and GecB) that allow it to use GSH as a source of cysteine. Using murine models of C. difficile infection, we also show that C. difficile uses its toxins to increase available GSH in the GI tract during infection.