Induced by anaerobisis (at protein level). A member of the dormancy regulon. Induced in response to reduced oxygen tension (hypoxia), low levels of nitric oxide (NO) and carbon monoxide (CO). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. A fairly frequent variant (Ala-64) was originally (PubMed:17970586) suggested to be responsible for some cases of rifampicin resistance. This has since been shown not to be true (PubMed:18550732), although it is a good marker for the Beijing-W clade/SCG-2 phylogenetic group.