Cytochrome P450 monooxygenase; part of the gene cluster that mediates the biosynthesis of aculins (PubMed:26374386). The pathway begins with the synthesis of 6-methylsalicylic acid by the polyketide synthase (PKS) acuA via condensation of acetate and malonate units (PubMed:26374386). The 6-methylsalicylic acid decarboxylase acuB then catalyzes the decarboxylation of 6-methylsalicylic acid to yield m-cresol (also known as 3-methylphenol) (Probable). These first reactions occur in the cytosol (By similarity). The intermediate m-cresol is then transported into the endoplasmic reticulum where the cytochrome P450 monooxygenase acuC converts it to m-hydroxybenzyl alcohol, which is further converted to gentisyl alcohol by the cytochrome P450 monooxygenase acuD (Probable). Gentisyl alcohol is further oxidized by the oxidoreductase acuE that probably catalyzes hydroxylation of the aromatic ring (Probable). The aromatic system might then be opened by oxidation through a Baeyer-Villiger type of oxidation, which could be catalyzed by acuF, with the carboxylic acid at C-1 subsequently reduced to an aldehyde by acuG (Probable). Subsequently, a hemiacetal is formed, before the dehydrogenase acuH would reduce the double bond between C-4 and C-6 (Probable). Finally, keto-enol tautomerism results in formation of aculinic acid, which exists as two diastereomers (both R/S configurations at C-1) by non-enzymatic hemiacetal formation (Probable). The carboxypeptidase acuI could be involved in the linking of aculinic acid to an aculene A moiety produced by the aculene biosynthesis cluster and which leads to the production of aculin A (Probable). AcuI may also be involved in the attachment of proline to aculinic acid to form epi-aculins A and B (Probable). 3-methylphenol + O2 + reduced [NADPH--hemoprotein reductase] = 3-hydroxybenzyl alcohol + H(+) + H2O + oxidized [NADPH--hemoprotein reductase] Secondary metabolite biosynthesis. Belongs to the cytochrome P450 family.