Biosynthesis of the Halogenated Mycotoxin Aspirochlorine in Koji Mold Involves a Cryptic Amino Acid Conversion
Biosynthesis of the Halogenated Mycotoxin Aspirochlorine in Koji Mold Involves a Cryptic Amino Acid Conversion
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DOI：
10.1002/anie.201407624
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发表时间：
2014-12-01
影响因子：
16.6
通讯作者：
Hertweck, Christian
中科院分区：
文献类型：
--
作者：
Chankhamjon, Pranatchareeya;Boettger-Schmidt, Daniela;Hertweck, Christian
Aspirochloride（1）是一种由曲霉菌（Aspergillus mold）产生的epidithiodiketopiperazine（ETP）毒素，其在东方烹饪中使用已超过2000年。考虑到其潜在的食品安全风险，我们阐明了螺氯生物合成的分子基础。通过遗传和化学分析相结合，我们找到了acl基因位点，并确定了AclH作为氯酶的关键作用。稳定的同位素标记，生物转化，和突变实验，分析中间体和体外腺苷酸化结构域测定得到了完全出乎意料的见解acl途径：而不是一个苯丙氨酸和一个甘氨酸，两个苯丙氨酸单位组装的迭代非核糖体肽合成酶（NRPS，AcIP），然后卤化和前所未有的苯丙氨酸甘氨酸氨基酸转换。生物测定表明，这两个氨基酸的转换所需的真菌毒素赋予细胞毒性和抗真菌活性。
Aspirochlorine (1) is an epidithiodiketopiperazine (ETP) toxin produced from koji mold (Aspergillus oryzae), which has been used in the oriental cuisine for over two millennia. Considering its potential risk for food safety, we have elucidated the molecular basis of aspirochlorine biosynthesis. By a combination of genetic and chemical analyses we found the acl gene locus and identified the key role of AclH as a chlorinase. Stable isotope labeling, biotransformation, and mutational experiments, analysis of intermediates and an in vitro adenylation domain assay gave totally unexpected insights into the acl pathway: Instead of one Phe and one Gly, two Phe units are assembled by an iterative non-ribosomal peptide synthetase (NRPS, AclP), followed by halogenation and an unprecedented Phe to Gly amino acid conversion. Biological assays showed that both amino acid transformations are required to confer cytotoxicity and antifungal activity to the mycotoxin.