Based on the structural information of acetylaszonalenin isolated from Neosartorya fischeri, a putative biosynthetic gene cluster was identified in the genome sequence of this fungus by genomic mining. This cluster consists of three genes coding for a putative non-ribosomal peptide synthetase (AnaPS), a prenyltransferase (AnaPT), and an acetyltransferase (AnaAT). The coding sequences of anaPT and anaAT were cloned in pQE70 and pQE60, respectively, and overexpressed in Escherichia coli. The soluble His 6 fusion proteins were purified to near homogeneity and characterized biochemically. The structures of the enzymatic products were elucidated by NMR and mass spectroscopy analysis. AnaPT was found to catalyze the reverse prenylation of (

Dermatophytes belonging to the Trichophyton and Arthroderma genera cause skin infections in humans and animals. From genome sequencing data, we mined a conserved gene cluster among dermatophytes that are homologous to one that produces an immunosuppressive polyketide in Aspergillus fumigatus. Using a recombination-based cloning strategy in yeast, we constructed fungal heterologous expression vectors that encode the cryptic clusters. When integrated into the model Aspergillus nidulans host, a structurally related compound neosartoricin B was formed, suggesting a possible role of this compound in the pathogenesis of these strains.

Small molecules (SMs) play central roles as virulence factors of pathogenic fungi and bacteria; however, genomic analyses suggest that the majority of microbial SMs have remained uncharacterized. Based on microarray analysis followed by comparative metabolomics of overexpression/knockout mutants we identified a tryptophan-derived iron(III)-complex, hexadehydroastechrome (HAS), as the major product of the cryptic has non-ribosomal peptide synthetase (NRPS) gene cluster in the human pathogen Aspergillus fumigatus. Activation of the has cluster created a highly virulent A. fumigatus strain that increased mortality of infected mice. Comparative metabolomics of different mutant strains allowed to propose a pathway for HAS biosynthesis and further revealed cross-talk with another NRPS pathway producing the anti-cancer fumitremorgins.

Filamentous fungi produce a variety of secondary metabolites of diverse beneficial and detrimental activities to humankind. The genes encoding the enzymatic machinery required to make these metabolites are typically clustered in fungal genomes. There is considerable evidence that secondary metabolite gene regulation is, in part, by transcriptional control through hierarchical levels of transcriptional regulatory elements involved in secondary metabolite cluster regulation. Identification of secondary metabolism regulatory elements could potentially provide a means of increasing production of beneficial metabolites, decreasing production of detrimental metabolites, aid in the identification of ‘silent’ natural products and also contribute to a broader understanding of molecular mechanisms by which secondary metabolites are produced. This review summarizes regulation of secondary metabolism associated on transcriptional regulatory elements from a broad view as well as tremendous advances in discovery of cryptic or novel secondary metabolites by genomic mining in the basis of this knowledge.

Prenylated indole derivatives are hybrid natural products containing both aromatic and isoprenoid moieties and are widely spread in plants, fungi and bacteria. Some of these complex natural products, e.g. the ergot alkaloids ergotamine and fumigaclavine C as well as the diketopiperazine derivative fumitremorgin C and its biosynthetic precursors tryprostatin A and B, show a wide range of biological and pharmacological activities. Prenyl transfer reactions catalysed by prenyltransferases represent key steps in the biosynthesis of these compounds and often result in formation of products which possess biological activities distinct from their non-prenylated precursors. Recently, a series of putative indole prenyltransferase genes could be identified in the genome sequences of different fungal strains including Aspergillus fumigatus. The gene products show significant sequence similarities to dimethylallyltryptophan synthases from fungi. We have cloned and overexpressed six of these genes, fgaPT1, fgaPT2, ftmPT1, ftmPT2, 7-dmats and cdpNPT from A. fumigatus in E. coli and S. cerevisiae. The overproduced enzymes were characterised biochemically. Three additional prenyltransferases, DmaW-Cs, TdiB and MaPT were identified and characterised in a Clavicipitalean fungus, Aspergillus nidulans and Malbranchea aurantiaca, respectively. Sequence analysis and alignments with known aromatic prenyltransferases as well as phylogenetic analysis revealed that these enzymes belong to a new group of "aromatic prenyltransferases". They differ clearly from membrane-bound aromatic prenyltransferases from different sources and soluble prenyltransferases from bacteria. The characterised enzymes are soluble proteins, catalyse different prenyl transfer reactions on indole moieties of various substrates and do not require divalent metal ions for their enzymatic reactions. All of the enzymes accepted only dimethylallyl diphosphate as prenyl donor. On the other hand, they showed broad substrate specificity towards their aromatic substrates. Diverse tryptophan derivatives and tryptophan-containing cyclic dipeptides were accepted by these enzymes, providing a new strategy for convenient production of biologically active substances, e.g. by chemoenzymatic synthesis.

Purpureocillium lilacinum of Ophiocordycipitaceae is one of the most promising and commercialized agents for controlling plant parasitic nematodes, as well as other insects and plant pathogens. However, how the fungus functions at the molecular level remains unknown. Here, we sequenced two isolates (PLBJ-1 and PLFJ-1) of P. lilacinum from different places Beijing and Fujian. Genomic analysis showed high synteny of the two isolates, and the phylogenetic analysis indicated they were most related to the insect pathogen Tolypocladium inflatum. A comparison with other species revealed that this fungus was enriched in carbohydrate-active enzymes (CAZymes), proteases and pathogenesis related genes. Whole genome search revealed a rich repertoire of secondary metabolites (SMs) encoding genes. The non-ribosomal peptide synthetase LcsA, which is comprised of ten C-A-PCP modules, was identified as the core biosynthetic gene of lipopeptide leucinostatins, which was specific to P. lilacinum and T. ophioglossoides, as confirmed by phylogenetic analysis. Furthermore, gene expression level was analyzed when PLBJ-1 was grown in leucinostatin-inducing and non-inducing medium, and 20 genes involved in the biosynthesis of leucionostatins were identified. Disruption mutants allowed us to propose a putative biosynthetic pathway of leucinostatin A. Moreover, overexpression of the transcription factor lcsF increased the production (1.5-fold) of leucinostatins A and B compared to wild type. Bioassays explored a new bioactivity of leucinostatins and P. lilacinum: inhibiting the growth of Phytophthora infestans and P. capsici. These results contribute to our understanding of the biosynthetic mechanism of leucinostatins and may allow us to utilize P. lilacinum better as bio-control agent.

Summary The eukaryotic bZIP transcription factors are critical players in organismal response to environmental challenges. In fungi, the production of secondary metabolites (SMs) is hypothesized as one of the responses to environmental insults, e.g. attack by fungivorous insects, yet little data to support this hypothesis exists. Here we establish a mechanism of bZIP regulation of SMs through RsmA, a recently discovered YAP-like bZIP protein. RsmA greatly increases SM production by binding to two sites in the A. nidulans AflR promoter region, a C6 transcription factor known for activating production of the carcinogenic and anti-predation SM, sterigmatocystin (ST). Deletion of aflR in an overexpression rsmA (OE::rsmA) background not only eliminates ST production but also significantly reduces asperthecin synthesis. Furthermore, the fungivore, Folsomia candida, exhibited a distinct preference for feeding on wild type rather than an OE::rsmA strain. RsmA may thus have a critical function in mediating direct chemical resistance against predation. Taken together, these results suggest RsmA represents a bZIP pathway hardwired for defensive SM production.

Penilactones A and B consist of a γ-butyrolactone and two clavatol moieties. We identified two separate gene clusters for the biosynthesis of these key building blocks in Penicillium crustosum. Gene deletion, feeding experiments, and biochemical investigations proved that a nonreducing PKS ClaF is responsible for the formation of clavatol and the PKS-NRPS hybrid TraA is involved in the formation of crustosic acid, which undergoes decarboxylation and isomerization to the predominant terrestric acid. Both acids are proposed to be converted to γ-butyrolactones with involvement of a cytochrome P450 ClaJ. Oxidation of clavatol to hydroxyclavatol by a nonheme FeII/2-oxoglutarate-dependent oxygenase ClaD and its spontaneous dehydration to an ortho-quinone methide initiate the two nonenzymatic 1,4-Michael addition steps. Spontaneous addition of the methide to the γ-butyrolactones led to peniphenone D and penilactone D, which undergo again stereospecific attacking by methide to give penilactones A/B.