Catalyzes two sequential steps in the biosynthesis of coenzyme A. In the first step cysteine is conjugated to 4'-phosphopantothenate to form 4-phosphopantothenoylcysteine. In the second step the latter compound is decarboxylated to form 4'-phosphopantotheine. H(+) + N-[(R)-4-phosphopantothenoyl]-L-cysteine = (R)-4'-phosphopantetheine + CO2 (R)-4'-phosphopantothenate + CTP + L-cysteine = CMP + diphosphate + H(+) + N-[(R)-4-phosphopantothenoyl]-L-cysteine Binds 1 FMN per subunit. Cofactor biosynthesis; coenzyme A biosynthesis. Disruption of the gene results in CoA auxotrophy. In the N-terminal section; belongs to the HFCD (homo-oligomeric flavin containing Cys decarboxylase) superfamily. In the C-terminal section; belongs to the PPC synthetase family.