Reactive nitrogen species (RNS), like reactive oxygen species, have numerous target molecules in the bacterial cell, and Mtb has developed remedies to the most important ones of them. This is a key reason for its ability to stay alive in the hostile environment of the late phagosome within human macrophages.
Mtb repairs single-base DNA damage caused by DNA alkylation; it scavenges nitric oxide with large amounts of mycothiol and methionine-rich proteins (the nitroso compounds later being reduced). Nitric oxide and peroxynitrite are also directly reduced by a battery of hemoglobins and peroxiredoxins, supported by a network of thioredoxins and respective NADPH-dependent reductases (Fang. 2004).