Figure 1. A hypothesized mechanism by which CS may affect virulence of MTB. (A) With S. aureus, CS induces the expression of mprF, which adds positively charged lysine residues to the bacterial membrane phospholipids. With greater positive charge on its cell membrane, S. aureus is better able to repel cationic AMP⁺. (B) Similar to the mprF molecule in S. aureus, MTB possess the lysX gene, which encodes a 2-domain protein with lysyl transferase and lysyl-tRNA synthetase activities that also adds positively charged lysine residues to phosphatidylglycerol, converting the acidic, negatively-charged phospholipid to a basic, positively-charged phospholipid. While it is not known if CS can induce lysX gene, this may be another potential mechanism by which CS increases susceptibility to TB by inducing a more virulent MTB strain.