Abstract:

Organic molecules produced by living organisms, generally termed as natural products, are rich sources of pharmaceutical drugs and biopesticides, and fungi are one of the most prolific producers of medicinally important natural products, as represented by penicillins, lovastatin, and cyclosporins. Heterologous expression is a commonly used approach to study the function of biosynthetic genes of natural products, and a number of heterologous hosts have been developed and utilized over the last decades. The filamentous fungus Aspergillus oryzae has long been utilized for the production of fermented food and drinks in East Asia, and intensive genetic and molecular biological studies on the fungus have allowed for its genetic engineering in an efficient manner. Importantly, A. oryzae is known to possess a relatively clean metabolic background with a low level of secondary metabolite production, providing an attractive feature as a heterologous host. Furthermore, unlike prokaryotic and yeast hosts, most coding sequences of fungal biosynthetic proteins can be directly introduced into A. oryzae in their intact form without removing introns, which simplifies the transformation procedures. Collectively, A. oryzae is a robust platform for heterologous production of natural products, which not only facilitates the elucidation of the biosynthetic pathway of a given natural product but also allows the activation of silent or cryptic biosynthetic gene clusters. Thus, the A. oryzae host has been widely utilized for biosynthetic studies, genome mining, and synthetic biology of fungal natural products. It should be noted that more than ten biosynthetic genes can readily be introduced into the fungus, indicating that the majority of fungal biosynthetic gene clusters can be easily transferred to the A. oryzae host. This review first provides the general transformation procedure of A. oryzae and the molecular biological tools available for the fungus. Next, recent successful applications of this fungal host for the heterologous production of natural products are summarized. With the recent rapid advance in molecular biology, such as the development of genome editing tools, we believe that the heterologous expression of biosynthetic genes in A. oryzae will be performed in a much faster and more versatile manner in the near future, which would ultimately lead to the discovery of useful natural products for drug leads and other applications.

Key words: Aspergillus oryzae, heterologous expression, natural products, biosynthesis, synthetic biology

摘要：

天然产物是创新药物和生物农药研发的重要源泉。阐明天然产物生物合成关键基因的功能、解析其生物合成通路和酶催化机制对于促进功能天然产物的应用和开发至关重要。异源表达是研究天然产物生物合成和合成生物学的重要手段之一。近年来，米曲霉异源宿主得到了广泛的应用。通过基因工程技术，将目的天然产物生物合成基因和基因簇在米曲霉中异源表达，不仅能够有效地激活沉默的生物合成基因和基因簇，挖掘全新活性天然产物，而且可以快速高效地鉴定天然产物生物合成基因功能，解析和重构其生物合成途径。米曲霉异源表达宿主已经成为天然产物合成生物学研究的强有力工具。本文对米曲霉遗传转化系统在天然产物研究中的应用进行了系统综述。首先，概述了异源表达的应用和意义，介绍了米曲霉遗传转化系统的发展过程、应用基础和优势以及遗传转化方法的实践和优化。其次，根据不同天然产物的结构类型和与之相对应的合成酶特点，着重介绍了该体系表达各类天然产物的成功案例。最后，对米曲霉异源表达宿主在天然产物化学领域的研究和应用前景进行了总结和展望。随着基因编辑、定向进化、合成生物学、生物信息学技术以及人工智能技术的发展和应用，米曲霉异源表达宿主的发展和完善将会极大地促进更多天然产物化学研究技术的发展和革新，以期为天然产物合成生物学的研究和创新药物研发提供借鉴。

关键词: 米曲霉, 异源表达, 天然产物, 生物合成, 合成生物学