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Aculene
Aculenes are a unique class of norsequiterpenes (C14) that are produced by Aspergillus aculeatus. There are five different forms of aculenes, A-E, including keto alcohol forms and their corresponding esters with L-proline. It has been discovered that the keto alcohol aculenes C,D, and E show inhibitory effect on quorum sensing while the biological activity of the aculenes A and B still remain unknown.

Biosynthesis
The biosynthesis of aculene A starts with conversion of Farnesyl pyrophosphate (FPP) to dauca-4,7-diene catalyzed by Class I terpene cyclase AneC. Then, a cytochrome P450 monooxygenase AneF converts the methyl group into a carboxylic acid, followed by installation of hydroxy group by a second cytochrome P450 monooxygenase AneD. AneG, a third cytochrome P450 monooxygenase, installs an electron-withdrawing carbonyl group at the C-2 position. Once the C-2 keto group is formed, it tartomerizes to the enol intermediate. Then, relocalization of the enol proton yield the next intermediate that is set to decarboxylation. Protonation then yield the product, aculene D.

AneA is phytanoyl-CoA dioxygenase to install unsaturation, which is responsible for conversion from aculene D to aculene C or from aculene B to aculene A. AneB is a single-module Nonribosomal peptide synthetase (NRPS) with adenylation and thiolation domain. It adenylates L-proline. AneE is an α, β-hydrolase that catalyzes the transfer of L-proline from AneB to the sesquiterpene moiety.