phosphopantetheine adenylyltransferase domain of eukaryotic and archaeal bifunctional enzymes
The PPAT domain of the bifunctional enzyme with PPAT and DPCK functions. The final two steps of the CoA biosynthesis pathway are catalyzed by phosphopantetheine adenylyltransferase (PPAT) and dephospho-CoA (dPCoA) kinase (DPCK). The PPAT reaction involves the reversible adenylation of 4'-phosphopantetheine to form 3'-dPCoA and PPi, and DPCK catalyses phosphorylation of the 3'-hydroxy group of the ribose moiety of dPCoA. In eukaryotes the two enzymes are part of a large multienzyme complex . Studies in Corynebacterium ammoniagenes suggested that separate enzymes were present, and this was confirmed through identification of the bacterial PPAT/CoAD.