Transferases;
Acyltransferases;
Transferring groups other than aminoacyl groups
BRITE hierarchy

(methyl)malonyl-CoA:long-chain acyl-[(phenol)carboxyphthiodiolenone synthase] (methyl)malonyltransferase {carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase]-forming}

(1) 3 malonyl-CoA + 2 (S)-methylmalonyl-CoA + icosanoyl-[(phenol)carboxyphthiodiolenone synthase] + 5 NADPH = C32-carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CoA + 5 NADP+ + 5 CO2 + 2 H2O;
(2) 3 malonyl-CoA + 2 (S)-methylmalonyl-CoA + docosanoyl-[(phenol)carboxyphthiodiolenone synthase] + 5 NADPH = C34-carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CoA + 5 NADP+ + 5 CO2 + 2 H2O;
(3) 3 malonyl-CoA + 2 (S)-methylmalonyl-CoA + 19-(4-hydroxyphenyl)-nonadecanoyl-[(phenol)carboxyphthiodiolenone synthase] + 5 NADPH = C37-(phenol)carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CoA + 5 NADP+ + 5 CO2 + 2 H2O;
(4) 3 malonyl-CoA + 2 (S)-methylmalonyl-CoA + 17-(4-hydroxyphenyl)heptadecanoyl-[(phenol)carboxyphthiodiolenone synthase] + 5 NADPH = C35-(phenol)carboxyphthiodiolenone-[(phenol)carboxyphthiodiolenone synthase] + 5 CoA + 5 NADP+ + 5 CO2 + 2 H2O

malonyl-CoA [CPD:C00083];
(S)-methylmalonyl-CoA [CPD:C00683];
icosanoyl-[(phenol)carboxyphthiodiolenone synthase] [CPD:C22226];
NADPH [CPD:C00005];
docosanoyl-[(phenol)carboxyphthiodiolenone synthase];
19-(4-hydroxyphenyl)-nonadecanoyl-[(phenol)carboxyphthiodiolenone synthase];
17-(4-hydroxyphenyl)heptadecanoyl-[(phenol)carboxyphthiodiolenone synthase]

The enzyme, which is a complex of five polyketide synthase proteins, is involved in the synthesis of the lipid core common to phthiocerols and phenolphthiocerols. The first protein, PpsA, can accept either a C18 or C20 long-chain fatty acyl, or a (4-hydroxyphenyl)-C17 or C19 fatty acyl. The substrates must first be adenylated by EC 6.2.1.59, long-chain fatty acid adenylase/transferase FadD26, which also loads them onto PpsA. PpsA then extends them using a malonyl-CoA extender unit. The PpsB protein adds the next malonyl-CoA extender unit. The absence of a dehydratase and an enoyl reductase domains in the PpsA and PpsB modules results in the formation of the diol portion of the phthiocerol moiety. PpsC adds a third malonyl unit (releasing a water molecule due to its dehydratase domain), PpsD adds an (R)-methylmalonyl unit, releasing a water molecule, and PpsE adds a second (R)-methylmalonyl unit, without releasing a water molecule. The incorporation of the methylmalonyl units results in formation of two branched methyl groups in the elongated product. The enzyme does not contain a thioesterase domain [2], and release of the products requires the tesA-encoded type II thioesterase [1].

EC 2.3.1.292 created 2019

1  [PMID:15668773]

2  [PMID:15749014]