Kishimoto Shinji, Matsubara Yuya, Watanabe Kenji
Department of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
J Am Chem Soc. 2022 Mar 30;144(12):5485-5493. doi: 10.1021/jacs.1c13621. Epub 2022 Mar 18.
Ergopeptines constitute one of the representative classes of ergoline alkaloids and carry a tripeptide extension on the lysergic acid core. In the current study, we discovered and structurally characterized newly isolated ergopeptine-like compounds named lentopeptins from a filamentous fungus , a close relative of . Interestingly, in lentopeptins, the common lysergic acid moiety of ergopeptines is replaced by a cinnamic acid moiety at the N-terminus of the peptide segment. Moreover, lentopeptins lack the C-terminal proline residue necessary for the spontaneous cyclization of the peptide extension. Herein, we report the atypical lentopeptin biosynthetic pathway identified through targeted deletion of the cluster biosynthetic genes predicted from the genome sequence. Further characterizations of the thiolation-terminal condensation-like (T-C) didomain of the nonribosomal peptide synthetase LenA and its site-specific mutants revealed the mechanism of peptide release diketopiperazine formation, an activity previously unreported for C domains. Most intriguingly, assays of the cytochrome P450 LenC illuminated the unique mechanisms to generate two diastereomeric products. Lentopeptin A forms a stereospecific hydroxylation, followed by a spontaneous bicyclic lactam core formation, while lentopeptin B is produced through an initial dehydrogenation, followed by a bicyclic lactam core formation and stereospecific hydration. Our results showcase how nature exploits common biosynthetic enzymes to forge new complex natural products effectively (213/250).
麦角肽类是麦角灵生物碱的代表性类别之一，在麦角酸核心上带有一个三肽延伸结构。在本研究中，我们从一种丝状真菌（与……的近亲）中发现并对新分离出的名为扁豆肽的类麦角肽化合物进行了结构表征。有趣的是，在扁豆肽中，麦角肽类常见的麦角酸部分在肽段的N端被肉桂酸部分所取代。此外，扁豆肽缺乏肽延伸自发环化所需的C端脯氨酸残基。在此，我们报告了通过对基因组序列预测的簇生物合成基因进行靶向缺失鉴定出的非典型扁豆肽生物合成途径。对非核糖体肽合成酶LenA的硫醇化末端缩合样（T-C）双结构域及其位点特异性突变体的进一步表征揭示了肽释放和二酮哌嗪形成的机制，这是一种以前未报道过的C结构域活性。最引人注目的是，细胞色素P450 LenC的分析揭示了生成两种非对映体产物的独特机制。扁豆肽A通过立体特异性羟基化形成，随后自发形成双环内酰胺核心，而扁豆肽B则通过最初的脱氢，随后形成双环内酰胺核心和立体特异性水合作用产生。我们的结果展示了大自然如何利用常见的生物合成酶有效地制造新的复杂天然产物（213/250）。
