Unified Biosynthetic Origin of the Benzodipyrrole Subunits in CC-1065
Unified Biosynthetic Origin of the Benzodipyrrole Subunits in CC-1065
复制标题
CC-1065 中苯并二吡咯亚基的统一生物合成起源
DOI：
10.1021/acschembio.7b00302
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发表时间：
2017
影响因子：
4
通讯作者：
Tang Gong-Li
中科院分区：
文献类型：
--
作者：
Wu Sheng;Jiang Xiao-Hong;Yuan Hua;Jin Wen-Bing;Yin Yue;Wang Ling-Yun;Zhao Juan;Tang Gong-Li
CC-1065是天然抗生素家族的第一个特征成员，包括具有异常强效抗肿瘤活性的yatakemycin和duocarmycins。CC-1065含有三个苯并二吡咯（1a-，1b-和1c-），其中1a-亚基是由环丙烷环组成的，并且苯并二吡咯环的生物形成机制仍然是难以捉摸的。此前，CC-1065的生物合成研究仅限于放射性标记的前体喂养实验，该实验表明酪氨酸（Tyr）和丝氨酸（Ser）被掺入到两个苯并二吡咯中，（1b-和1c-）亚基通过相同的模式，但这不同于具有N1-C2-C3的来自Ser的关键环丙苯并二吡咯（1a-）亚基。CC-1065的生物合成基因簇已被克隆、分析，并通过一系列基因失活来表征。值得注意的是，来自Δ c10 C突变体的带有C7-OH基团的关键中间体表现出改善的细胞毒性。此外，这些数据启发我们怀疑1a亚基可能采用与1b和1c亚基相同的前体掺入模式。随后，13 C标记的Tyr补料实验证实N1-C2-C3是通过作为中间体的DOPA由Tyr产生的。总的来说，苯并二吡咯的生物合成途径，提出了一个修订和统一的前体掺入模式，这意味着一个氧化环化策略的组装苯并二吡咯。本工作为进一步研究新的DNA烷基化类似物的酶促机制和组合生物合成奠定了基础。
CC-1065 is the first characterized member of a family of naturally occurring antibiotics including yatakemycin and duocarmycins with exceptionally potent antitumor activity. CC-1065 contains three benzodipyrroles (1a-,1b-, and1c-) of which the 1a-subunit is remarkable by being composed of a cyclopropane ring, and the mechanism for the biological formation of benzodipyrrole rings remains elusive. Previously, biosynthetic studies of CC-1065 were limited to radioactively labeled precursor feeding experiments, which showed that tyrosine (Tyr) and serine (Ser) were incorporated into the two benzodipyrrole (1b- and1c-) subunits via the same mode but that this was different from the key cyclopropabenzodipyrrole (1a-) subunit with N1–C2–C3 derived from Ser. Herein, the biosynthetic gene cluster of CC-1065 has been cloned, analyzed, and characterized by a series of gene inactivations. Significantly, a key intermediate bearing a C7-OH group derived from a Δc10Cmutant exhibited improved cytotoxicity. Moreover, this data inspired us to suspect that the1a-subunit might employ the same precursor incorporation mode as the1b- and1c-subunits. Subsequently,13C-labeled Tyr feeding experiments confirmed that the N1–C2–C3 is originated from Tyr via DOPA as an intermediate. Collectively, a biosynthetic pathway of benzodipyrrole is proposed featuring a revised and unified precursor incorporation mode, which implicates an oxidative cyclization strategy for the assembly of benzodipyrrole. This work sets the stage for further study of enzymatic mechanisms and combinatorial biosynthesis for new DNA alkylating analogues.