Phosphopantetheine adenylyltransferase (PPAT; ) is an essential enzyme in bacteria, responsible for catalyzing the rate-limiting step in coenzyme A (CoA) biosynthesis: catalysis of the reversible transfer of an adenylyl group from ATP to 4'-phosphopantetheine to give dephospho-CoA (DPCOA) and pyrophosphate in the fourth (and penultimate) step of coenzyme A biosynthesis []. The dinucleotide-binding fold of PPAT is homologous to class I aminoacyl-tRNA synthetases [, ]. CoA has been shown to inhibit PPAT and competes with ATP, PhP, and dPCoA. PPAT is a homohexamer in E. coli [, ].The enzyme had previously been thought to have a role in lipopolysaccharide biosynthesis [].
