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. 2021 Dec;13(6):822-829.
doi: 10.1111/1758-2229.13013. Epub 2021 Oct 10.

Novel angular naphthopyrone formation by Arp1p dehydratase involved in Aspergillus fumigatus melanin biosynthesis

Natsuki Nambu  1 , Huei-Fung Tsai  2 , Yun C Chang  2 , K J Kwon-Chung  2 , Tomoki Yoshida  3 , Nobutada Tanaka  3 , Hiroshi Tomoda  3 , Yutaka Ebizuka  1 , Isao Fujii  1   3
Affiliations

Novel angular naphthopyrone formation by Arp1p dehydratase involved in Aspergillus fumigatus melanin biosynthesis

Natsuki Nambu et al. Environ Microbiol Rep. 2021 Dec.

Abstract

Conidial pigment is an important virulence factor in Aspergillus fumigatus, a human fungal pathogen. The biosynthetic gene cluster for 1,8-dihydroxynaphthalene (DHN)-melanin in A. fumigatus consists of six genes, alb1, ayg1, arp1, arp2, abr1 and abr2. In contrast to black DHN-melanin fungi such as Magnaporthe grisea, the polyketide synthase Alb1p in A. fumigatus produces naphthopyrone YWA1 instead of 1,3,6,8-THN (T4HN) and YWA1 is converted to T4HN by Ayg1p. The yeast transformant expressing Alb1p and Arp1p dehydratase produced an unknown compound which was identified to be a novel angular naphthopyrone named YWA3 formed from YWA1. In addition, the amount of YWA3 produced was much more than that of YWA2 formed by non-enzymatic dehydration from YWA1. To further analyse the reaction in vitro, Arp1p was overexpressed in E. coli and purified. Kinetic analysis revealed Km value of Arp1p for YWA1 to be 41 μM which is comparable with that of Ayg1p for YWA1 in conversion to T4HN. The complex structure modelling well explained the mechanism of YWA3 generation by the dehydration of angular YWA1 by Arp1p. These results indicated the possibility that polymerization of angular naphthopyrone YWA3 but not YWA2 could be involved in the characteristic bluish-green conidial pigmentation of A. fumigatus.

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Conflict of interest statement

Conflicts of interest. None declared.

Figures

Fig. 1.
Fig. 1.. Proposed biosynthesis of A. fumigatus spore pigments and its biosynthetic gene cluster.
YWA3 was identified in this study. The dashed arrow indicates its possible involvement in A. fumigatus spore pigment biosynthesis.
Fig. 2.
Fig. 2.. HPLC analysis of products of S. cerevisiae INVSc1-npgA transformants.
1: S. cerevisiae INVSc1-npgA/pYES-DEST52 (control transformant), 2: S. cerevisiae INVSc1-npgA/pYES-alb1, 3: S. cerevisiae INVSc1-npgA/pYES-alb1+p424-ayg1+pESC-arp2, 4: authentic scytalone, 5: S. cerevisiae INVSc1-npgA/pYES-alb1+pESC-arp1. *Background peak was observed in the control transformant.
Fig. 3.
Fig. 3.
Structure of YWA3 and its formation from YWA1 via open side-chain intermediate.
Fig. 4.
Fig. 4.. SDS-PAGE analysis of Arp1p-HT purification fractions.
Lane 1, standard protein markers; lane 2, E. coli BL21-Codon Plus (DE3)-RIPL/pET-3d soluble fraction; 3, E. coli BL21-Codon Plus (DE3)-RIPL/pET-arp1HT soluble fraction; 4, Arp1p-HT nickel-affinity purified fraction.
Fig. 5.
Fig. 5.. Predicted binding models of substrates in the active sites of SDH and Arp1p.
Hydrogen bonds are shown in dotted lines. The structures were visualized by PyMOL (The PyMOL Molecular Graphics System, Version 2.0 Schrödinger, LLC.).
See this image and copyright information in PMC

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References

    1. Basarab GS, Steffens JJ, Wawrzak Z, Schwartz RS, Lundqvist T, and Jordan DB (1999) Catalytic mechanism of scytalone dehydratase: site-directed mutagenesis, kinetic isotope effects, and alternate substrates. Biochem 38: 6012–6024. - PubMed
    1. Fujii I, Yasuoka Y, Tsai H-F, Chang YC, Kwon-Chung KJ, and Ebizuka Y (2004) Hydrolytic polyketide shortening by Ayg1p, a novel enzyme involved in fungal melanin biosynthesis. J Biol Chem 279: 4613–44620. - PubMed
    1. Gietz RD, Schiestl RH, Willems AR, and Woods RA (1995) Studies on the transformation of intact yeast cells by the LiAc/SS-DNA/PEG procedure. Yeast 15: 355–360. - PubMed
    1. Gorst-Allman CP, Steyn PS, and Rabie CJ (1980) Structural elucidation of the nigerones, four new naphthopyrones from cultures of Aspergillus niger. J Chem Soc Perkin Trans 1 2474–2479.
    1. Hashida-Okada T, Ogawa A, Kato I, and Takesako K (1998) Transformation system for prototrophic industrial yeasts using the AUR1 gene as a dominant selection marker. FEBS Lett 425: 117–122. - PubMed

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