Has a dual function in uptake of nutrients and induction of host cell death. The N-terminal domain (NTD) forms an outer membrane channel and is used for uptake of nutrients across the outer membrane. The secreted C-terminal toxic domain (TNT) acts as a glycohydrolase, which hydrolyzes the essential cellular coenzyme NAD(+) in the cytosol of infected macrophages, leading to necrotic host cell death. Both functions are required for survival, replication and cytotoxicity of M.tuberculosis in macrophages. H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Glycohydrolase activity is completely inhibited by interaction with the immunity factor for TNT (IFT). This inhibition protects M.tuberculosis from self-poisoning. kcat is 52 sec(-1). Optimum pH is 6.5. Interacts with the immunity factor for TNT (IFT) (PubMed:26237511). Oligomer formation is required for channel activity (PubMed:24753609). Secreted into the cytosol of infected macrophages while the bacteria are still confined to the phagosome. Access to the macrophage cytosol depends on the ESX-1 / type VII secretion system (T7SS). The C-terminal toxic domain is cleaved, probably after integration of CpnT into the outer membrane. Deletion reduces growth on glycerol and glucose as sole carbon sources. Deletion mutant does not replicate in differentiated THP-1 macrophages and lacks cytotoxicity (PubMed:24753609). Lack of cpnT does not increase drug resistance in vitro (PubMed:25645841). Deletion mutant does not decrease NAD(+) levels in infected macrophages (PubMed:26237511).