Lae1 regulates expression of multiple secondary metabolite gene clusters in Fusarium verticillioides.
ABSTRACT The filamentous fungus Fusarium verticillioides can cause disease of maize and is capable of producing fumonisins, a family of toxic secondary metabolites linked to esophageal cancer and neural tube defects in humans and lung edema in swine and leukoencephalomalacia in equines. The expression of fumonisin biosynthetic genes is influenced by broad-domain transcription factors (global regulators) and Fum21, a pathway-specific transcription factor. LaeA is a global regulator that in Aspergillus nidulans, affects the expression of multiple secondary metabolite gene clusters by modifying heterochromatin structure. Here, we employed gene deletion analysis to assess the effect of loss of a F. verticillioides laeA orthologue, LAE1, on genome-wide gene expression and secondary metabolite production. Loss of Lae1 resulted in reduced expression of gene clusters responsible for synthesis of the secondary metabolites bikaverin, fumonisins, fusaric acid and fusarins as well as two clusters for which the corresponding secondary metabolite is unknown. Analysis of secondary metabolites revealed that, in contrast to a previously described Fusarium fujikuroi lae1 mutant, bikaverin production is reduced. Fumonisin production is unchanged in the F. verticillioides lae1 mutant. Complementation of the F. verticillioides mutant resulted in increased fumonisin production.
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ABSTRACT: Dimeric basic leucine zipper (bZIP) proteins are conserved transcriptional enhancers found in all eukaryotes. A recently reported and novel function for bZIPs is association of these proteins with secondary metabolite production in filamentous fungi. In particular a Yap-like bZIP termed RsmA ( r estorer of s econdary m etabolism A) was identified in Aspergillus nidulans that positively regulates the carcinogen sterigmatocystin. To assess for conserved function for RsmA, we examined a role of this protein in secondary metabolism in the pathogen A. fumigatus. RsmA was found to positively regulate gliotoxin where overexpression (OE) of rsmA led to 2–100 fold increases of twelve gli cluster metabolites in culture medium including the newly identified gli metabolite cyclo(L-Phe-L-Ser). Lungs from both wild type and OErsmA infected mice coPLoS ONE 05/2013; 8(5):e62591. · 3.73 Impact Factor
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ABSTRACT: Abstract Fusarium genus contains a large number of species which occur in all climate zones and are pathogenic to agriculturally important crops. The majority of the species produce secondary metabolites, many of which are toxic to plants, animals and humans. The core biosynthetic genes display conserved organization (gene clusters), and a common expression pattern due to synchronized regulation. Although broadly specified enzymatic activities are present in different metabolic paths, the reactions catalyzed by those are limited to a specific step and no compensation effect is observed when the essential gene from one of the clusters is disrupted. Still, inter- and intraspecific diversity of the core biosynthetic genes is consistently higher than that of housekeeping genes, even though the biochemical specificity is maintained. Thus, the core biosynthetic genes of known sequence and structure emerge as good targets for designing tools aimed at the discrimination of closely related (and economically important) Fusarium species. The review covers the present and potential use of sequence analysis and biosynthetic gene-derived molecular markers as applied to taxonomic and chemotype studies, utilizing both toxic (fumonisins, trichothecenes, zearalenone, fusaric acid, fusarins, enniatins and beauvericin) and nontoxic (bikaverin) metabolites produced by Fusarium fungi.Critical Reviews in Microbiology 05/2014; 40(2):176-185. · 5.07 Impact Factor
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ABSTRACT: The hallmark trait of fungal secondary-metabolite gene clusters is well established, consisting of contiguous enzymatic and often regulatory gene(s) devoted to the production of a metabolite of a specific chemical class. Unexpectedly, we have found a deviation from this motif in a subtelomeric region of Aspergillus fumigatus. This region, under the control of the master regulator of secondary metabolism, LaeA, contains, in its entirety, the genetic machinery for three natural products (fumitremorgin, fumagillin, and pseurotin), where genes for fumagillin and pseurotin are physically intertwined in a single supercluster. Deletions of 29 adjoining genes revealed that fumagillin and pseurotin are coregulated by the supercluster-embedded regulatory gene with biosynthetic genes belonging to one of the two metabolic pathways in a noncontiguous manner. Comparative genomics indicates the fumagillin/pseurotin supercluster is maintained in a rapidly evolving region of diverse fungal genomes. This blended design confounds predictions from established secondary-metabolite cluster search algorithms and provides an expanded view of natural product evolution.Proceedings of the National Academy of Sciences 09/2013; · 9.74 Impact Factor