Functional Characterization of TtnD and TtnF, Unveiling New Insights into Tautomycetin Biosynthesis

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• 作者：Yinggang Luo ; Wenli Li ; Jianhua Ju ; Qiuping Yuan ; Noel R. Peters ; F. Michael Hoffmann ; Sheng-Xiong Huang ; Tim S. Bugni ; Scott Rajski ; Hiroyuki Osada ; Ben Shen
• 刊名：Journal of the American Chemical Society
• 出版年：2010
• 出版时间：May 19, 2010
• 年：2010
• 卷：132
• 期：19
• 页码：6663-6671
• 全文大小：304K
• 年卷期：v.132,no.19(May 19, 2010)
• ISSN：1520-5126

文摘

The biosynthetic gene cluster for tautomycetin (TTN), a highly potent and selective protein phosphatase (PP) inhibitor isolated from Streptomyces griseochromogenes, has recently been cloned and sequenced. To better understand the transformations responsible for converting the post-polyketide synthase product into the exciting anticancer and immunosuppressive chemotherapeutic candidate TTN, we produced and characterized new analogues resulting from inactivation of two genes, ttnD and ttnF, in S. griseochromogenes. Inactivation of ttnD and ttnF, which encode for putative decarboxylase and dehydratase enzymes, respectively, afforded mutant strains SB13013 and SB13014. The ΔttnD mutant SB13013 accumulated four new TTN analogues, TTN D-1, TTN D-2, TTN D-3, and TTN D-4, whereas the ΔttnF mutant accumulated only one new TTN analogue, TTN F-1. The accumulation of these new TTN analogues defines the function of TtnD and TtnF and the timing of their chemistries in relation to installation of the C5 ketone moiety within TTN. Notably, all new analogues possess a structurally distinguishing carboxylic acid moiety, revealing that TtnD apparently cannot catalyze decarboxylation in the absence of TtnF. Additionally, cytotoxicity and PP inhibition assays reveal the importance of the functional groups installed by TtnDF and, consistent with earlier proposals, the C2′′−C5 fragment of TTN to be a critical structural determinant behind the important and unique PP-1 selectivity displayed by TTN.