Enniatin complex

Fusarium head blight (FHB) is a disease of small-grain cereals and corn caused by a complex of fungal species of the genus Fusarium. The disease reduces the yield and quality of seeds and results in the accumulation of various mycotoxins which cause a variety of toxic effects on humans and livestock. Beauvericin (BEA) and enniatins (ENs) are a group of toxins with antimicrobial, insecticidal and phytotoxic activities produced mainly by F. avenaceum, F. poae and F. tricinctum. In this study, primer sets were designed that were targeted to esyn1 gene homologs encoding multifunctional enzyme enniatin synthetase. Primers used in multiplex PCR amplified products from the FHB species reported to produce (ENs) and/or BEA. The use of the marker developed on asymptomatic wheat seed samples originating from Northern and Southern Poland demonstrated that all samples were positive for the presence of potential enniatin-producing Fusarium species.

Cyclosporin A and its homologues are synthesized by a single multifunctional enzyme from their precursor amino acids. Cyclosporin synthetase is a polypeptide chain with a molecular mass of approximately 800 kDa. In 3% polyacrylamide-sodium dodecyl sulfate gels it shows a single band of approximately 650 kDa, which appears to not be glycosylated. The enzyme could be purified to near-homogeneity in five steps. A 72-fold purification was obtained. All constitutive amino acids of cyclosporins are activated as thioesters via aminoadenylation by the same enzyme. Then N-methylation of the thioester-bound amino acids which are present in methylated form in the cyclosporin molecule takes place, whereby S-adenosyl-L-methionine serves as the methyl group donor. Methyltransferase activity is an integral entity of the enzyme; this could be shown by a photoaffinity labeling method. 4'-Phosphopantetheine is a prosthetic group of cyclosporin synthetase similar to other peptide and depsipeptide synthetases.

Fungi of the genus Fusarium are important plant pathogens and contaminants of cereal grains producing different types of mycotoxins. Enniatins are a group of mycotoxins with ionophoric properties frequently detected in North European grains. Within the Fusarium complex responsible for grain infection, Fusarium avenaceum, Fusarium poae and Fusarium tricinctum are the most potential enniatins producers. This study presents the development of two quantitative TaqMan MGB (Minor Groove Binder) assays for the specific quantification of F. avenaceum/F. tricinctum and F. poae esyn1 genotypes, respectively. Two sets of genotype-specific primers/probes were designed on the basis of esyn1 gene homologues encoding multifunctional enzyme enniatin synthetase. The specificity of the assays developed has been tested successfully on 111 Fusarium isolates from different geographical origins. The detection limits for F. avenaceum/F. tricinctum esyn1 genotype and F.