Inducible cysteine synthesis by CysK2 provides copper resistance in Mycobacterium tuberculosis.

CysK2-mediated cysteine synthesis enables Mycobacterium tuberculosis to resist copper toxicity, with a key amino acid substitution in H37Rv reducing this ability.

• Why it matters: Copper toxicity is a host defense mechanism against M. tuberculosis, but the bacterial strategies to counteract this stress are not fully understood, limiting therapeutic development.
• What they did: Researchers identified a single amino acid change in CysK2 in H37Rv that impairs its copper resistance, and demonstrated that CysK2 functions as a cysteine synthase essential for copper detoxification.
• The result: This work links cysteine biosynthesis to copper resistance in M. tuberculosis, revealing a potential target for new treatments that enhance host immune effectiveness.