Synthesis of Unnatural Alkaloid Scaffolds by Exploiting Plant Polyketide Synthase
Synthesis of unnatural alkaloid scaffolds by exploiting plant polyketide synthase Hiroyuki Moritaa,b, Makoto Yamashitaa, She-Po Shia,1, Toshiyuki Wakimotoa,b, Shin Kondoc, Ryohei Katoc, Shigetoshi Sugioc,2, Toshiyuki Kohnod,2, and Ikuro Abea,b,2 aGraduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; bJapan Science and Technology Agency, Core Research of Evolutional Science and Technology, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan; cBiotechnology Laboratory, Mitsubishi Chemical Group Science and Technology Research Center Inc., 1000 Kamoshida, Aoba, Yokohama, Kanagawa 227-8502, Japan; and dMitsubishi Kagaku Institute of Life Sciences, 11 Minamiooya, Machida, Tokyo 194-8511, Japan Edited by Jerrold Meinwald, Cornell University, Ithaca, NY, and approved July 12, 2011 (received for review May 15, 2011) HsPKS1 from Huperzia serrata is a type III polyketide synthase (PKS) club moss Huperzia serrata (HsPKS1) (19) (Fig. S1), using precur- with remarkable substrate tolerance and catalytic potential. Here sor-directed and structure-based approaches. As previously re- we present the synthesis of unnatural unique polyketide–alkaloid ported, HsPKS1 is a unique type III PKS that exhibits unusually hybrid molecules by exploiting the enzyme reaction using precur- broad substrate specificity to produce various aromatic polyke- sor-directed and structure-based approaches. HsPKS1 produced tides. For example, HsPKS1, which normally catalyzes the sequen- novel pyridoisoindole (or benzopyridoisoindole) with the 6.5.6- tial condensations of 4-coumaroyl-CoA (1) with three molecules fused (or 6.6.5.6-fused) ring system by the condensation of 2-carba- of malonyl-CoA (2) to produce naringenin chalcone (3)(Fig.1A), moylbenzoyl-CoA (or 3-carbamoyl-2-naphthoyl-CoA), a synthetic also accepts bulky N-methylanthraniloyl-CoA (4)asastarterto nitrogen-containing nonphysiological starter substrate, with two produce 1,3-dihydroxy-N-methylacridone (5), after three conden- molecules of malonyl-CoA.
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