Part of the PpsABCDE complex involved in the biosynthesis of the lipid core common to phthiocerols and phenolphthiocerols by successive additions of malonyl-CoA or methylmalonyl-CoA extender units (PubMed:15749014, PubMed:20553505). PpsA can accept as substrate the activated forms of either icosanoyl (C20), docosanoyl (C22) or lignoceroyl (C24) groups from FadD26, or a (4-hydroxyphenyl)-C17 or (4-hydroxyphenyl)-C19 fatty acyl from FadD29 (PubMed:15749014, PubMed:20553505). PpsA initiates the biosynthesis and extends its substrate using a malonyl-CoA extender unit. The PpsB and PpsC proteins add the second and third malonyl-CoA extender units. PpsD adds an (R)-methylmalonyl unit and PpsE adds a second (R)-methylmalonyl unit. The incorporation of the methylmalonyl units results in formation of two branched methyl groups in the elongated product (PubMed:15749014). 2 (S)-methylmalonyl-CoA + 10 H(+) + icosanoyl-[(phenol)carboxyphthiodiolenone synthase] + 3 malonyl-CoA + 5 NADPH = C32-carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CO2 + 5 CoA + 2 H2O + 5 NADP(+) 2 (S)-methylmalonyl-CoA + docosanoyl-[(phenol)carboxyphthiodiolenone synthase] + 10 H(+) + 3 malonyl-CoA + 5 NADPH = C34-carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CO2 + 5 CoA + 2 H2O + 5 NADP(+) 2 (S)-methylmalonyl-CoA + 17-(4-hydroxyphenyl)heptadecanoyl-[(phenol)carboxyphthiodiolenone synthase] + 10 H(+) + 3 malonyl-CoA + 5 NADPH = C35-(phenol)carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CO2 + 5 CoA + 2 H2O + 5 NADP(+) 2 (S)-methylmalonyl-CoA + 19-(4-hydroxyphenyl)nonadecanoyl-[(phenol)carboxyphthiodiolenone synthase] + 10 H(+) + 3 malonyl-CoA + 5 NADPH = C37-(phenol)carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CO2 + 5 CoA + 2 H2O + 5 NADP(+) Binds 1 phosphopantetheine covalently. Lipid metabolism; fatty acid biosynthesis. The C-terminal region interacts with TesA (PubMed:15668773). Interacts with MmpL7 (PubMed:16201014). Deletion of this gene results in phthiocerol dimycocerosates (DIM) deficiency and decreases the ability of the bacteria to infect macrophages. Was identified as a high-confidence drug target.