Recently, the team of Professor Rao Yijian of the School of Bioengineering of our university has made important progress in the construction of synthetic biology strategies to construct unnatural perylraquinone compounds that are superior to nature, and the research result "mechanistic investigation on c c bond cle**age of anthraquinone catalyzed by an atypical nonheme iron-dependent". Dioxygenase BTG13 "** Published in Angewandte Chemie International Edition (IF=16.).6)(
Benzylquinone compounds are considered to be one of the ideal photosensitizers in photodynamics**. However, natural perylene quinone compounds have the disadvantages of poor photostability, high dark toxicity and non-selectivity. In order to discover the perylquinone compounds with excellent properties, Rao Yijian's team at Jiangnan University adopted the branched metabolic pathway based on class B perylloquinone compoundsThe synthetic biology strategy reprogrammed the biosynthetic pathway of cercosporin, enabling the biosynthesis of a series of derivatives with different configurations and substituents。Among them,The unnatural perylquinone compound Cercosporin A not only has high photostability and very low dark toxicity, but also retains good photodynamic antibacterial and anticancer activities。In addition, the study found that cercosporin can be selectively enriched in cells, providing a potential target for the drug development of perylquinone compounds and broadening the pipeline for drug discovery from nature.
First, the authors isolated and preserved the high-yielding cercosporin strain cercosporasp. in the laboratoryJNU001 was used as the research object, and the mechanism of the diversity and complexity of the product formed by the modification of the common precursor by the common precursor of the class B perylloquinone natural products was revealed through gene knockout, in vitro remodeling and bioinformatics analysis, and then a series of reprogrammed gene clusters were obtained through the knockout and introduction of branching enzymes using the pyrosporin biosynthesis gene cluster as a template, which not only realized the transformation of the axial chirality of perylquinone compounds, but also obtained a series of unnatural perylloquinone compounds with different substituents. In addition, the authors performed detailed tests on substrate promiscancy of key branching enzymes to provide guidance for the directed biosynthesis of other unnatural perylloquinone compounds.
Subsequently, the authors selected several natural or unnatural perylloquinone compounds with typical structures to investigate the effects of the chemical structure of perylloquinone on its photodynamic properties in terms of photophysical properties, quantum yield of singlet oxygen, and biological activity. The results showed that the perylloquinone compound with a special skeletal structureThe absorption in the red light region is significantly enhanced; In addition, compared with natural perylloquinone compounds, the unnatural perylloquinone compound Cercosporin not only has higher photostability and significantly reduced dark toxicity, but also retains good photodynamic antibacterial and anticancer activities.
In order to explain the reasons for the reduction of the dark toxicity of the unnatural perylquinone compound Cercosporine, the authors first analyzed the differences in the distribution of different perylloquinone compounds on the cell surface. Different from the uniform distribution of cercosporine on cells, the unnatural perylquinone compound cercosporin was selectively enriched on the cell surface. At the same time, the analysis of apoptosis, DNA oxidative damage and lipid oxidation levels showed that cercosporin produced only trace amounts of reactive oxygen species under dark conditions, so it had low dark toxicity.
In summary, Professor Rao Yijian's team used synthetic biology methods to reprogram the natural cercosporin biosynthesis pathway, and obtained unnatural perylloquinone compounds that are superior to nature, which solved the problems of poor photostability, high dark toxicity and non-selectivity of natural perylloquinone compounds, and laid a solid foundation for the drug development of perylloquinone compounds.
The above work was published in Angewandte Chemie International Edition, with Professor Rao Yijian as the corresponding author, and Jiangnan University Ph.D. students Su Zengping and Guo Baodang as the co-first authors. The above research work was supported by the National Key R&D Program of China (2018YFA0901700), the National Natural Science Program of China (32270082), the Natural Science of Jiangsu Province (BK20202002), and the Graduate Research and Practice Innovation Project of Jiangsu Province (KYCX21 2020).
Design and biosynthesis of unnatural perylene quinone compounds.