| Enzyme Function |
FUNCTION: Part of the tra gene cluster that produces terrestric acid (PubMed:30811183). The clavatol biosynthesis cluster cla and the terrestric acid cluster tra are both involved in the production of peniphenones and penilactones (PubMed:30811183). The non-reducing PKS claF is responsible for the formation of clavatol from successive condensations of 3 malonyl-CoA units, presumably with a simple acetyl-CoA starter unit, and 2 methylation steps (PubMed:30811183). The esterase claE probably collaborates with claF by catalyzing the hydrolysis of ACP-bound acyl intermediates to free the ACP from stalled intermediates (By similarity). The clavatol oxidase claD then converts clavatol to hydroxyclavatol (PubMed:30811183). Spontaneous dehydration of hydroxyclavatol leads to the accumulation of the highly active ortho-quinone methide (PubMed:30811183, PubMed:31860310). On the other hand, the PKS-NRPS hybrid traA is involved in the formation of crustosic acid, with the help of traB and traD (PubMed:30811183). The polyketide synthase module (PKS) of traA is responsible for the synthesis of the polyketide backbone via the condensation of an acetyl-CoA starter unit with 3 malonyl-CoA units (PubMed:30811183). The downstream nonribosomal peptide synthetase (NRPS) module then amidates the carboxyl end of the polyketide with L-malic acid (PubMed:30811183). Because traA lacks a designated enoylreductase (ER) domain, the required activity is provided the enoyl reductase traG (By similarity). Crustosic acid undergoes decarboxylation and isomerization to the terrestric acid, catalyzed by the 2-oxoglutarate-dependent dioxygenase traH (PubMed:30811183). Both acids are further converted to the 2 gamma-butyrolactones (R)-5-methyltetronic acid and (S)-5-carboxylmethyltetronic acid, with involvement of the cytochrome P450 monooxygenase claJ (PubMed:30811183). Spontaneous addition of the methide to these gamma-butyrolactones leads to peniphenone D and penilactone D, which undergo again stereospecific attacking by methide to give penilactones A and B (PubMed:30811183, PubMed:31860310). TraE seems not to be involved in the biosynthesis of peniphenones and penilactones in the conditioons used to study its function (PubMed:30811183). {ECO:0000250|UniProtKB:A0A0E0RXA7, ECO:0000250|UniProtKB:A0A161CKG1, ECO:0000269|PubMed:30811183, ECO:0000269|PubMed:31860310}. |