Aflatoxin Biosynthesis: Regulation and Subcellular Localization

Aflatoxins are polyketide-derived secondary metabolites synthesized by specific Aspergillus species when they grow on a variety of susceptible plants, including economically important crops such as corn, cotton seed, peanuts, and tree nuts. Human aflatoxin exposure is strongly associated with liver and lung cancer, stunted growth, and immune suppression and these impacts generate strong pressure to reduce or eliminate aflatoxin contamination in food and feed. Initially, we provide a brief review of aflatoxin biosynthesis and toxicity. Then, we review how and where aflatoxin is synthesized in the mold and provide details of regulation of this process at the level of transcription and subcellular localization. We also explore the regulatory network that enables A. parasiticus to co-regulate diverse cellular functions including secondary metabolism, conidiospore development, and stress response. This review focuses significant attention on recent work from our laboratory but draws on the work of others to illustrate key concepts related to regulation of aflatoxin biosynthesis at the level of transcription and subcellular localization.