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 (By similarity). Required for growth and persistence in mice (PubMed:27676316). 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. Inhibited by coenzyme A (CoA) and CoA thioesthers (PubMed:33420031). Two related chemical scaffolds that potently inhibit the activity of the CoaB moiety of CoaBC through a cryptic allosteric site that sits in the dimer interface region of the CoaB enzyme were identified (PubMed:33420031). Cofactor biosynthesis; coenzyme A biosynthesis; CoA from (R)-pantothenate: step 2/5. Cofactor biosynthesis; coenzyme A biosynthesis; CoA from (R)-pantothenate: step 3/5. Homododecamer. Transcriptional silencing of this gene leads to growth attenuation and results in a bactericidal phenotype in vitro and in vivo, whether initiated at infection or during either the acute or chronic stages of infection. Was identified as a high-confidence drug target. 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.