Isolation, structural elucidation and biosynthesis of 3-hydroxy-6-dimethylallylindolin-2-one, a novel prenylated indole derivative from Actinoplanes missouriensis.
Many prenylated indole derivatives are widely distributed in nature. Recently, two Streptomyces prenyltransferases, IptA and its homolog SCO7467, were identified in the biosynthetic pathways for 6-dimethylallylindole (DMAI)-3-carbaldehyde and 5-DMAI-3-acetonitrile, respectively. Here, we isolated a novel prenylated indole derivative, 3-hydroxy-6-dimethylallylindolin (DMAIN)-2-one, based on systematic purification of metabolites from a rare actinomycete, Actinoplanes missouriensis NBRC 102363. The structure of 3-hydroxy-6-DMAIN-2-one was determined by HR-MS and NMR analyses. We found that A. missouriensis produced not only 3-hydroxy-6-DMAIN-2-one but also 6-dimethylallyltryptophan (DMAT) and 6-DMAI when grown in PYM (peptone-yeast extract-MgSO4) medium. We searched the complete genome of A. missouriensis for biosynthesis genes of these compounds and found a gene cluster composed of an iptA homolog (AMIS_22580, named iptA-Am) and a putative tryptophanase gene (AMIS_22590, named tnaA-Am). We constructed a tnaA-Am-deleted (ΔtnaA-Am) strain and found that it produced 6-DMAT but did not produce 6-DMAI or 3-hydroxy-6-DMAIN-2-one. Exogenous addition of 6-DMAI to mutant ΔtnaA-Am resulted in the production of 3-hydroxy-6-DMAIN-2-one. Furthermore, in vitro enzyme assays using recombinant proteins produced by Escherichia coli demonstrated that 6-DMAI was synthesized from tryptophan and dimethylallyl pyrophosphate in the presence of both IptA-Am and TnaA-Am, and that IptA-Am preferred tryptophan to indole as the substrate. From these results, we concluded that the iptA-Am-tnaA-Am gene cluster is responsible for the biosynthesis of 3-hydroxy-6-DMAIN-2-one. Presumably, tryptophan is converted into 6-DMAT by IptA-Am and 6-DMAT is then converted into 6-DMAI by TnaA-Am. 6-DMAI appears to be converted into 3-hydroxy-6-DMAIN-2-one by the function of some unknown oxidases in A. missouriensis.
Department of Biotechnology, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo, Japan.
Ryutaro
R
Satou
Japan Biological Informatics Consortium (JBIC), Tokyo, Japan.
Miho
M
Izumikawa
Department of Biotechnology, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo, Japan.
Yohei
Y
Katsuyama
Department of Biotechnology, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo, Japan.
Misato
M
Matsui
Japan Biological Informatics Consortium (JBIC), Tokyo, Japan.
Motoki
M
Takagi
National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan.
Kazuo
K
Shin-ya
Department of Biotechnology, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo, Japan.
Yasuo
Y
Ohnishi
D000498:Allyl Compounds / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D003311:Cord Factors / Q000737:chemistry / Q000302:isolation & purification*; D004122:Dimethylallyltranstransferase / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D016680:Genome, Bacterial; D007211:Indoles / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008848:Micromonosporaceae / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D010088:Oxidoreductases / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
C063099:6-deoxy-6-mycoloylamino-alpha,alpha-trehalose; D000498:Allyl Compounds; D003311:Cord Factors; D007211:Indoles; D011994:Recombinant Proteins; D014364:Tryptophan; D010088:Oxidoreductases; D004122:Dimethylallyltranstransferase