Advances in understanding the biosynthesis of fumonisins

Fumonisins are a group of economically important, polyketide-derived mycotoxins. Since the cloning of the fumonisin polyketide synthase (PKS) gene from Fusarium verticillioides in 1999, significant advances have been made in understanding the molecular mechanisms for fumonisin biosynthesis. A cluster of 17 genes (FUM) required for fumonisin biosynthesis, regulation, and possibly resistance has been extensively studied using gene disruption, domain swapping, and heterologous expression approaches. Genetic manipulations of the fumonisin PKS gene have shed light on the mechanism by which highly-reducing PKSs control polyketide structure. Heterologous expression and examination of reactions catalyzed by the corresponding enzymes has reveled the role of some FUM genes in fumonisin biosynthesis. Together, these efforts have established a general biosynthetic pathway for fumonisins and revealed several fascinating enzymatic reactions. In spite of the progress, many questions remain. Future efforts should focus on addressing the molecular mechanistic details of assembly, release, and tailoring of the fumonisin polyketide chain.