Title: Diversity of polyketide synthases in Fusarium Authors
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 10, 2013
Publication Date: July 10, 2013
Citation: Brown, D.W., Proctor, R.H. 2013. Diversity of polyketide synthases in Fusarium. In: Brown, D.W., Proctor R.H., editors. Fusarium: Genomics, Molecular and Cellular Biology. Norwich, United Kingdom: Horizon Scientific Press. p. 143-164. Technical Abstract: Fusarium can produce a structurally diverse array of secondary metabolites (SMs) with a range of biological activities, including pigmentation, plant growth regulation, and toxicity to humans and other animals. Contamination of grain-based food and feed with toxic SMs produced by Fusarium is associated with a variety of diseases in plants and animals and results in loss of millions of dollars in grain commodities each year. Many SMs are formed via the activities of a family of large enzymes called polyketide synthases (PKSs) that consist of between five and eight functional domains. This Chapter reviews the structures and functions of Fusarium PKSs present in four species, Fusarium verticillioides, Fusarium graminearum, Fusarium solani, and Fusarium oxysporum. Each genome has between 11 and 16 PKS genes. Re-examination of inferred phylogenetic relationships of deduced amino acid sequences provides insight into how this gene family evolved. The geneaologies suggest that collectively the Fusarium PKSs represent 39 distinct PKS homologs, where each set catalyzes synthesis of a structurally distinct polyketide. Variation in the Fusarium PKS genes is due to both ancient and recent gene duplications, gene loss events, gain-of-function due to the acquisition of new domains and of loss-of-function due to nucleotide mutations. The significant number and variety of evolutionary changes reflects the vast biosynthetic chemical potential this gene family provides fungi that may help address ever changing living conditions. Understanding how fungal polyketides arise will lead to better methods to control their synthesis thereby reducing their negative impact on man and saving limited natural resources.