Hideaki Oikawa

Recent studies on enzymes catalyzing the Diels- Alder reaction. often named "Diels-Alderases", clearlydemonstrated the involvement of this synthetically useful reaction in the biosynthesis of natural products.This review covers natural Diels-Alder type cycloadducts. synthetic efforts on the chemical feasibility ofthe biosynthctic Diels - Alder reaction and a brief history of studies on Diels-Alderases. In addition,reaction mechanisms of artificial and natural Diels--Alderases are discussed.

The crude enzyme from Alternaria solani is able to catalyse the [4 + 2] cycloaddition of prosolanapyrone III 6 to the exo adduct solanapyrone A 1 whose optical purity is estimated as 92 ± 8% e.e. by HPLC analysis monitored using a CD spectrometer; this enzyme also catalyses the oxidation and [4 + 2] cycloaddition of prosolanapyrone II 5 to 1 with 99 ± 4% e.e.

The biosynthetic machinery of the first fungal ribosomally synthesized and post-translationally modified peptide (RiPP) ustiloxin B was elucidated through a series of gene inactivation and heterologous expression studies. The results confirmed an essential requirement for novel oxidases possessing the DUF3328 motif for macrocyclization, and highly unique side-chain modifications by three oxidases (UstCF1F2) and a pyridoxal 5'-phosphate (PLP)-dependent enzyme (UstD). These findings provide new in

Penitrem A is one of the most elaborated members of the fungal indole diterpenes. Two separate penitrem gene clusters were identified using genomic and RNA sequencing data, and 13 out of 17 transformations in the penitrem biosynthesis were elucidated by heterologous reconstitution of the relevant genes. These reactions involve 1) a prenylation-initiated cationic cyclization to install the bicyclo[3.2.0]heptane skeleton (PtmE), 2) a two-step P450-catalyzed oxidative processes forming the unique t

A unique highly reducing polyketide synthase (HR-PKS) with a reductase domain was identified in a betaenone biosynthetic gene cluster. Successful heterologous expression and characterization of the HR-PKS and trans-acting enoyl reductase (ER) provide insights into the core structure formation with a decalin scaffold and allow reconstitution of the betaenone biosynthetic machinery.

The syntheses of prosolanapyrones I (6) and II (7) via the aldol reactions of pyrone and dienal segments have been achieved in five steps in 31% overall yield for 6 and seven steps in 5% overall yield for 7. An improved synthetic route starting from vinylpyrone 27 provided 7 in 11 steps in 12% overall yield. The enzymatic Diels−Alder reaction of 7 affords (−)-solanapyrone A (1) with high enantioselectivity and with good exo-selectivity, which is difficult to attain by chemical methods. In additi

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFirst Direct Evidence in Biological Diels-Alder Reaction of Incorporation of Diene-Dienophile Precursors in the Biosynthesis of SolanapyronesHideaki Oikawa, Yuichi Suzuki, Akira Naya, Kinya Katayama, and Akitami IchiharaCite this: J. Am. Chem. Soc. 1994, 116, 8, 3605–3606Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://pubs.acs.org/doi/10.1021/ja00087a059https://doi.org/10.1021/ja

Macrophomate synthase from the fungus Macrophoma commelinae IFO 9570 is a Mg(II)-dependent dimeric enzyme that catalyzes an extraordinary, complex five-step chemical transformation from 2-pyrone and oxalacetate to benzoate involving decarboxylation, C-C bond formation, and dehydration. The catalytic mechanism of the whole pathway was investigated in three separate chemical steps. In the first decarboxylation step, the enzyme loses oxalacetate decarboxylation activity upon incubation with EDTA. A

Reconstitution of the biosynthetic machinery for fungal secondary metabolites in Aspergillus oryzae provides an opportunity both for stepwise determination of the biosynthetic pathways and the total biosynthesis of fungal natural products. However, to maximize the utility of the reconstitution system, a simple and rapid strategy for the introduction of heterologous genes into A. oryzae is required. In this study, we demonstrated an effective method for introducing multiple genes involved in the

The biosynthetic gene cluster of antifungal agent jawsamycin (FR-900848) has been identified by heterologous expression. A series of gene inactivations and in vitro and in vivo analysis of key enzymes in the biosynthetic pathway established their functions. A novel mechanism involving a radical S-adenosyl methionine (SAM) cyclopropanase collaborating with an iterative polyketide synthase is proposed for the construction of the unique polycyclopropanated backbone. Our reconstitution system sets t

The biosynthesis of the antitumor agent GKK1032A(2) (1) has been investigated by administration of isotopically labeled ((13)C and (2)H) precursors to Penicillium sp. GKK1032. These studies showed that the backbone of 1 is constructed from l-tyrosine and a nonaketide chain flanked with five methyl groups probably by a polyketide synthase and a nonribosomal peptide synthetase hybrid. On the basis of the oxidation level of the starter unit and unusual 13-membered macroether formation between the t

Asperipin-2a is a ribosomally synthesized and post-translationally modified peptide isolated from Asperigillus flavus. Herein, we report the heterologous production of asperipin-2a and determination of its absolute structure. Notably, the characteristic bicyclic structure was likely constructed by a single oxidase containing the DUF3328 domain.