Solanapyrone Synthase,a Possible Diels–Alderase and Iterative Type I Polyketide Synthase Encoded in a Biosynthetic Gene Cluster from Alternaria solani |
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| Authors: | Ken Kasahara Dr. Takanori Miyamoto Takashi Fujimoto Hiroki Oguri Dr. Tetsuo Tokiwano Dr. Hideaki Oikawa Prof. Yutaka Ebizuka Prof. Isao Fujii Prof. |
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| Affiliation: | 1. Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, Tokyo 113‐0033 (Japan);2. Present address: Neo‐Morgan Laboratory Inc., Biotechnology Research Center, Teikyo University, 907 Nogawa, Miyamae‐ku, Kawasaki, Kanagawa 216‐0001 (Japan);3. Graduate School of Science, Hokkaido University, Kita 10 Nishi 8, Sapporo 060‐0810 (Japan);4. Present address: Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010‐0195 (Japan);5. School of Pharmacy, Iwate Medical University, 2‐1‐1 Nishitokuta, Yahaba, Iwate 028‐3694 (Japan), Fax: (+81)?19‐698‐1923 |
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| Abstract: | The solanapyrone biosynthetic gene cluster was cloned from Alternaria solani. It consists of six genes—sol1–6—coding for a polyketide synthase, an O‐methyltransferase, a dehydrogenase, a transcription factor, a flavin‐dependent oxidase, and cytochrome P450. The prosolanapyrone synthase (PSS) encoded by sol1 was expressed in Aspergillus oryzae and its product was identified as desmethylprosolanapyrone I ( 8 ). Although PSS is closely related to the PKSs/Diels–Alderases LovB and MlcA of lovastatin and compactin biosynthesis, it did not catalyze cycloaddition. Sol5, encoding a flavin‐dependent oxidase (solanapyrone synthase, SPS), was expressed in Pichia pastoris and purified. The purified recombinant SPS showed activity for the formation of (?)‐solanapyrone A ( 1 ) from achiral prosolanapyrone II ( 2 ), establishing that this single enzyme catalyzes both the oxidation and the subsequent cycloaddition reaction, possibly as a Diels–Alder enzyme. |
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| Keywords: | biological Diels– Alder reaction biosynthesis gene sequencing polyketide synthases solanapyrone |
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