Necessary for the biosynthesis of coenzyme A. Catalyzes the decarboxylation of 4-phosphopantothenoylcysteine to form 4'-phosphopantotheine (By similarity). H(+) + N-[(R)-4-phosphopantothenoyl]-L-cysteine = (R)-4'-phosphopantetheine + CO2 Binds 1 FMN per subunit. Cofactor biosynthesis; coenzyme A biosynthesis; CoA from (R)-pantothenate: step 3/5. Homotrimer. Belongs to the HFCD (homooligomeric flavin containing Cys decarboxylase) superfamily.