Adenylyl cyclase (AC) class IV-like, a subgroup of the CYTH-like superfamily
This subgroup contains class IV ACs and similar proteins. AC catalyzes the conversion of ATP to 3',5'-cyclic AMP (cAMP) and PPi. cAMP is a key signaling molecule which conveys a variety of signals in different cell types. In prokaryotes, cAMP is a catabolite derepression signal which triggers the expression of metabolic pathways including the lactose operon. Six non-homologous classes of ACs have been identified (I-VI). Class IV ACs are found in this group. In bacteria, the gene encoding Class IV AC has been designated cyaB and the protein as AC2. AC-IV occurs in addition to AC-I in bacterial pathogens such as Yersinia pestis (plague disease). The role of AC-IV is unknown but it has been speculated that it may be a factor in pathogenesis, perhaps providing cAMP for a secondary internal signaling function, or for secretion and uptake into host cells, where it may disrupt normal cellular processes. This subgroup belongs to the CYTH/triphosphate tunnel metalloenzyme (TTM)-like superfamily, whose enzymes have a unique active site located within an eight-stranded beta barrel.