LaeA调控黄曲霉毒素生物合成研究进展

RESEARCH PROGRESSES OF AFLATOXIN BIOSYNTHETIC REGULATION BY LAEA

黄曲霉毒素主要是由黄曲霉和寄生曲霉产生的一类具有较强的毒性和致癌能力的次级代谢产物,在霉变的小麦、玉米、棉花、花生等多种粮食及油料作物中检出率都比较高,给农业生产造成巨大的经济损失,严重威胁着食品安全及人类健康。自20世纪60年代发现黄曲霉毒素以来,人们对该毒素的理化性质、生物毒性、合成途径、产毒条件以及产毒调控机制做了大量的研究。该毒素的生物合成过程十分复杂,参与AF生物合成的基因有30多个,它们集聚在基因组上一个约80 kb称为AF基因簇的区域,该途径中每个基因的表达水平直接影响AF的合成量。研究表明黄曲霉毒素的生物合成受到多方面因素的调控,包括培养基成分如碳源、氮源、p H值,培养条件如培养温度、湿度等,途径专一性调控因子afl R及全局性调控因子Lae A等,Lae A能够调控丝状真菌的次级代谢及其生长发育,影响真菌形态分化、毒素合成及沉默基因的表达,相对于其调控因子表现出独特的性质。就Lae A在真菌中的发现、功能及调控机制等方面进行了综述,重点介绍了该调控因子在黄曲霉中调控黄曲霉毒素合成方面的研究进展,初步展示了黄曲霉毒素的生物合成调控模式,为今后进一步开展Lae A调控黄曲霉毒素合成调控机理的研究奠定了基础。

The highly mutagenic and carcinoge nic mycotoxin aflatoxin is mainly produced by Aspergillus flavus and Aspergillus parasiticus. The pathogenic fungus Aspergillus flavus contaminates wheat,corn,cotton,and peanuts pre-and post-harvest and can produce amount of aflatoxins which causes huge economic loss for the world agricultural economy and threathens food safety and human health. The physicochemical properties,biological toxicity,biosynthetic pathway,production conditions and regulatory mechanism of aflatoxin have been extensively studied since its discovery in 1960 s. More than thirty genes involved in aflatoxin biosynthetic pathway and clustered in an area about 80 Kb on a genome,named AF gene cluster,and the expression level of each gene can affect the production of aflatoxin. The previous research indicated that the biosynthesis of aflatoxin was regulated by several factors,including carbon source,nitrogen source,p H,temperature,humidity,pathway-specific regulator afl R,and global regulator Lae A,wherein Lae A showed unique properties,regulating secondary metabolism and development of filamentous fungi and affecting morphological differentiation of mycelia,aflatoxin synthesis and the expression of silent gene clusters. In order to provide information of Lae A for futher research,the paper summarized the discovery,function and regulation mechanism of Lae A in fungi,and emphasized on the latest progress of Lae A in regulating biosynthesis of Aspergillus flavus. This review presented the primary regulatory process of aflatoxin biosynthesis and will provide more insights into the research of aflatoxin regulated by Lae A.