Discovery of Key Dioxygenases that Diverged the Paraherquonin and Acetoxydehydroaustin Pathways in Penicillium brasilianum

Abstract

Paraherquonin (1), a fungal meroterpenoid produced by Penicillium brasilianum NBRC 6234, possesses a unique, highly congested hexacyclic molecular architecture. Here we identified the biosynthetic gene cluster of 1 (the prh cluster) and elucidated the pathway up to berkeleydione (2), which serves as the key intermediate for the biosynthesis of 1 as well as many other meroterpenoids. Interestingly, the nonheme iron and α-ketoglutarate-dependent dioxygenase PrhA constructs the cycloheptadiene moiety to afford 2 from preaustinoid A1 (6), probably via the homoallyl-homoallyl radical rearrangement. Additionally, another fungal strain, P. brasilianum MG11, which produces acetoxydehydroaustin instead of 1, was found to have a gene cluster nearly identical to the prh cluster. The dioxygenase encoded by the cluster shares 92% sequence identity with PrhA, and also accepts 6 but produces preaustinoid A3 (17) with a spiro-lactone system, generating a diverging point for the two different meroterpenoid pathways in the same species.

3,5‐Dimethylorsellinic Acid Derived Meroterpenoids from Eupenicillium sp. 6A‐9, a Fungus Isolated from the Marine Sponge Plakortis simplex

“…[27] Apparently, two steps involving ester hydrolyzation and methyl esterification of 7 give rise to 1-methoxy-hydropreaustinoid A1 (3). Meanwhile, as reported previously, [29] 7 is transformed into berkeleydione (16) via berkeleyone B (15) in two consecutive oxidations, also catalyzed by a multifunctional Fe II /α-KG-dependent dioxygenase, PrhA. To reach one of the final products proposed here, 22-deoxyminiolutelide B (6), the exo-methylene group of 16 would initially be oxidized to yield aldehyde b. C-8/C-9 retro-Claisen cleavage would then generate the ringopened intermediate c, and the acetal lactonization of c would yield berkeleyacetal A (9).…”

“…[30] Notably, the completely elucidated pathways for austinol [21,22,27] and berkeleydione, [29] for which the known compounds preaustinoid A1 (7) and preaustinoid A3 (10) acquired here are biosynthetic intermediates, enabled us to propose detailed mechanisms for the biosynthesis of the five related new meroterpenoids 1-5 (Scheme 1).…”

“…The biosynthesis of intriguing meroterpenoids metabolized by Aspergillus and Penicillium has been investigated for decades, and recently the molecular bases (biosynthetic genes/enzymes) for five 3,5-dimethylorsellinic acid (DMOA) and farnesyl pyrophosphate derived meroterpenoids, andrastin A, austinol, terretonin, anditomin, and berkeleydione, have been reported [20][21][22][23][24][25][26][27][28][29] and thoroughly reviewed. [30] Notably, the completely elucidated pathways for austinol [21,22,27] and berkeleydione, [29] for which the known compounds preaustinoid A1 (7) and preaustinoid A3 (10) acquired here are biosynthetic intermediates, enabled us to propose detailed mechanisms for the biosynthesis of the five related new meroterpenoids 1-5 (Scheme 1).…”

Biosynthesis of clinically used antibiotic fusidic acid and identification of two short-chain dehydrogenase/reductases with converse stereoselectivity

“…A similar phenomenon has also been found in the biosynthesis of citreohybridonol and paraherquoninv 23. , 24. .…”

A pharmaceutical model for the molecular evolution of microbial natural products

“…B) have illustrated how highly divergent products may be obtained through dynamic skeletal rearrangement . AusE and PrhA both utilize preaustinoid A1 as a substrate, but whereas the former catalyzes desaturation at C1–C2 and carbocyclic rearrangement to preaustinoid A3, the latter first desaturates at C5–C6, followed by rearrangement of the A/B‐ring to form berkeleydione. The functions of the two proteins could be interchanged by manipulating two amino acids in the vicinity of the A‐ring .…”