Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA.
Metab Eng. 2011 Nov;13(6):723-32. doi: 10.1016/j.ymben.2011.09.008. Epub 2011 Oct 1.
Cytochalasins are a group of fungal secondary metabolites with diverse structures and bioactivities, including cytochalasin E produced by Aspergillus clavatus, which is a potent anti-angiogenic agent. Here, we report the identification and characterization of the cytochalasin gene cluster from A. clavatus NRRL 1. As a producer of cytochalasin E and K, the genome of A. clavatus was analyzed and the ∼30 kb ccs gene cluster was identified based on the presence of a polyketide synthase-nonribosomal peptide synthetases (PKS-NRPS) and a putative Baeyer-Villiger monooxygenase (BVMO). Deletion of the central PKS-NRPS gene, ccsA, abolished the production of cytochalasin E and K, confirming the association between the natural products and the gene cluster. Based on bioinformatic analysis, a putative biosynthetic pathway is proposed. Furthermore, overexpression of the pathway specific regulator ccsR elevated the titer of cytochalasin E from 25mg/L to 175 mg/L. Our results not only shed light on the biosynthesis of cytochalasins, but also provided genetic tools for increasing and engineering the production.
细胞松弛素是一组结构和生物活性多样的真菌次级代谢产物，包括由棒曲霉（Aspergillus clavatus）产生的细胞松弛素 E，它是一种有效的抗血管生成剂。在这里，我们报告了从棒曲霉 NRRL 1 中细胞松弛素基因簇的鉴定和特征。作为细胞松弛素 E 和 K 的产生者，分析了棒曲霉的基因组，并根据存在聚酮合酶-非核糖体肽合酶（PKS-NRPS）和一个假定的 Baeyer-Villiger 单加氧酶（BVMO），鉴定了约 30kb 的 ccs 基因簇。删除中央 PKS-NRPS 基因 ccsA，会使细胞松弛素 E 和 K 的产生完全停止，这证实了天然产物与基因簇之间的关联。基于生物信息学分析，提出了一个假定的生物合成途径。此外，通路特异性调控因子 ccsR 的过表达将细胞松弛素 E 的产量从 25mg/L 提高到 175mg/L。我们的研究结果不仅阐明了细胞松弛素的生物合成，还为增加和工程化生产提供了遗传工具。
