title: Identification of (2S,3S)-β-Methyltryptophan as the Real Biosynthetic Intermediate of Antitumor Agent Streptonigrin.
abstract: Streptonigrin is a potent antitumor antibiotic, active against a wide range of mammalian tumor cells. It was reported that its biosynthesis relies on (2S,3R)-β-methyltryptophan as an intermediate. In this study, the biosynthesis of (2S,3R)-β-methyltryptophan and its isomer (2S,3S)-β-methyltryptophan by enzymes from the streptonigrin biosynthetic pathway is demonstrated. StnR is a pyridoxal 5'-phosphate (PLP)-dependent aminotransferase that catalyzes a transamination between L-tryptophan and β-methyl indolepyruvate. StnQ1 is an S-adenosylmethionine (SAM)-dependent C-methyltransferase and catalyzes β-methylation of indolepyruvate to generate (R)-β-methyl indolepyruvate. Although StnR exhibited a significant preference for (S)-β-methyl indolepyruvate over the (R)-epimer, StnQ1 and StnR together catalyze (2S,3R)-β-methyltryptophan formation from L-tryptophan. StnK3 is a cupin superfamily protein responsible for conversion of (R)-β-methyl indolepyruvate to its (S)-epimer and enables (2S,3S)-β-methyltryptophan biosynthesis from L-tryptophan when combined with StnQ1 and StnR. Most importantly, (2S,3S)-β-methyltryptophan was established as the biosynthetic intermediate of the streptonigrin pathway by feeding experiments with a knockout mutant, contradicting the previous proposal that stated (2S,3R)-β-methyltryptophan as the intermediate. These data set the stage for the complete elucidation of the streptonigrin biosynthetic pathway, which would unlock the potential of creating new streptonigrin analogues by genetic manipulation of the biosynthetic machinery.
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Dekun
authors: D
authors: Kong
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Yi
authors: Y
authors: Zou
authors: College of Life Science, Hebei University, Baoding 071002, P. R. China.
authors: Zhang
authors: Z
authors: Zhang
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Fei
authors: F
authors: Xu
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Nelson L
authors: NL
authors: Brock
authors: College of Life Science, Hebei University, Baoding 071002, P. R. China.
authors: Liping
authors: L
authors: Zhang
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Zixin
authors: Z
authors: Deng
authors: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic &Developmental Sciences, School of Life Sciences &Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P. R. China.
authors: Shuangjun
authors: S
authors: Lin
mesh_terms: D000970:Antineoplastic Agents / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000378:metabolism; D013058:Mass Spectrometry; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000032:analysis / Q000378:metabolism; D013237:Stereoisomerism; D013302:Streptomyces / Q000378:metabolism; D013308:Streptonigrin / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001426:Bacterial Proteins; C538978:beta-methyltryptophan; D013308:Streptonigrin; D012436:S-Adenosylmethionine; D014364:Tryptophan; D008780:Methyltransferases