PPCS, also known as phosphopantothenate--cysteine ligase, catalyzes the first step in the biosynthesis of coenzyme A (CoA) from pantothenic acid (vitamin B5), which is an essential universal pathway in prokaryotes and eukaryotes. PPCS, one of the last enzymes in this pathway, converts phosphopantothenate to phosphopantothenoylcysteine.