Synthaser: a CD-Search enabled Python toolkit for analysing domain architecture of fungal secondary metabolite megasynth(et)ases

Genome-wide identification and analysis of the NF-Y transcription factor family reveal its potential roles in tobacco (Nicotiana tabacum L.)

Nuclear Factor Y (NF-Y) represents a group of transcription factors commonly present in higher eukaryotes, typically consisting of three subunits: NF-YA, NF-YB, and NF-YC. They play crucial roles in the embryonic development, photosynthesis, flowering, abiotic stress responses, and other essential processes in plants. To better understand the genome-wide NF-Y domain-containing proteins, the protein physicochemical properties, chromosomal localization, synteny, phylogenetic relationships, genomic structure, promoter cis-elements, and protein interaction network of NtNF-Ys in tobacco (Nicotiana tabacum L.) were systematically analyzed. In this study, we identified 58 NtNF-Ys in tobacco, respectively, and divided into three subfamilies corresponding to their phylogenetic relationships. Their tissue specificity and expression pattern analyses for leaf development, drought and saline-alkali stress, and ABA response were carried out using RNA-seq or qRT-PCR. These findings illuminate the role of NtNF-Ys in regulating plant leaf development, drought and saline-alkali stress tolerance, and ABA response. This study offers new insights to enhance our understanding of the roles of NtNF-Ys and identify potential genes involved in leaf development, as well as drought and saline-alkali stress tolerance of plants.

Self-Resistance Gene-Guided Discovery of the Molecular Basis for Biosynthesis of the Fatty Acid Synthase Inhibitor Cerulenin

Cerulenin (1) is the first reported natural fatty acid synthase inhibitor and has been intensively researched for its antifungal, anticancer and anti-obesity properties. However, the molecular basis for its biosynthesis has remained a mystery for six decades. Here, we have identified the polyketide biosynthetic gene cluster (cer) responsible for the biosynthesis of 1 from two Sarocladium species using a self-resistance gene mining approach, which we validated via heterologous reconstitution of cer cluster in an Aspergillus nidulans host. Expression of various combinations of cer genes uncovered key pathway intermediates, electrocyclisation products derived from PKS-encoded polyenoic acids, and a suite of 13 new analogues of 1. This enabled us to establish a biosynthetic pathway to 1 that starts with a C12 polyketide precursor containing both E and Z double bonds and involves a complex series of epoxidations, double bond shifts, E/Z isomerisation and epoxide reduction. Using in vitro assays, we further validated the roles of amidotransferase CerD in amidation, and oxidase CerF and reductase CerE in the final two-electron oxidation and enone reduction steps towards 1. These findings expand our understanding of complex tailoring modifications in highly reducing PKS pathways and pave the way for the engineered biosynthesis of cerulenin analogues.

Genome Sequencing and Metabolic Potential Analysis of Irpex lacteus

Irpex lacteus is an edible and medicinal macrofungus with significant biological activity and broad pharmaceutical prospects that has received increasing attention in recent years. Although it is an important resource for macrofungi, knowledge of it remains limited. In this study, we sequenced, de novo assembled, and annotated the whole genome of I. lacteus using a PacBio Sequel II sequencer. The assembled 41.83 Mb genome contains 13,135 predicted protein-coding genes, 83.44% of which have searchable sequence similarity to other genes available in public databases. Using genome-based bioinformatics analysis, we identified 556 enzymes involved in carbohydrate metabolism and 103 cytochrome P450 proteins. Genome annotation revealed genes for key enzymes responsible for the biosynthesis of secondary metabolites, such as terpenoids and polyketides. Among them, we identified 14 terpene synthases, 8 NRPS-like enzymes, and 4 polyketide synthases (PKS), as well as 2 clusters of biosynthetic genes presumably related to terpene synthesis in I. lacteus. Gene family analysis revealed that the MYB transcription factor gene family plays an important role in the growth and development of I. lacteus. This study further enriches the genomic content of I. lacteus, provides genomic information for further research on the molecular mechanism of I. lacteus, and promotes the development of I. lacteus in the fields of drug research and functional food production.

Challenging Aromaticity: Revealing a Thioesterase Domain in a Fungal Nonreducing Polyketide Synthase Governing the Production of 3-Methylene Isochromanone

Thioesterase (TE) domain exerts a great influence over the structure of the final product and TE-released nonreduced polyketides (nrPKs) retain aromaticity. 3-Methylene isochromanones are lactones with a unique olefin at C3 that disrupts the aromaticity, whose biosynthetic details are speculative. Our study unveils the complete biosynthesis of ascochin, in which the construction of the 3-methylene isochromanone backbone is achieved by a nonreducing polyketide synthase (nrPKS) alone and two subsequent oxidations are involved. Intriguingly, the TEAscD serves as a gatekeeper to direct the product release toward formation of nonaromatic 3-methylene isochromanone, rather than the typical aromatic product.

Genome-wide characterization and metabolite profiling of Cyathus olla: insights into the biosynthesis of medicinal compounds

Cyathus olla, belonging to the genus Cyathus within the order Agaricales, is renowned for its bird's nest-like fruiting bodies and has been utilized in folk medicine. However, its genome remains poorly understood. To investigate genomic diversity within the genus Cyathus and elucidate biosynthetic pathways for medicinal compounds, we generated a high-quality genome assembly of C. olla with fourteen chromosomes. The comparative genome analysis revealed variations in both genomes and specific functional genes within the genus Cyathus. Phylogenomic and gene family variation analyses provided insights into evolutionary divergence, as well as genome expansion and contraction in individual Cyathus species and 36 typical Basidiomycota. Furthermore, analysis of LTR-RT and Ka/Ks revealed apparent whole-genome duplication (WGD) events its genome. Through genome mining and metabolite profiling, we identified the biosynthetic gene cluster (BGC) for cyathane diterpenes from C. olla. Furthermore, we predicted 32 BGCs, containing 41 core genes, involved in other bioactive metabolites. These findings represent a valuable genomic resource that will enhance our understanding of Cyathus species genetic diversity. The genome analysis of C. olla provides insights into the biosynthesis of medicinal compounds and establishes a fundamental basis for future investigations into the genetic basis of chemodiversity in this significant medicinal fungus.

Chemical structures, biological activities, and biosynthetic analysis of secondary metabolites of the Diatrypaceae family: A comprehensive review

The family Diatrypaceae is a less well-known group within the order Xylariales (Ascomycota). Initially, the focus on its metabolites was related to the pathogenicity of one of its members, Eutypa lata. To date, a total of 254 natural products have been identified from Diatrypaceae strains. These compounds include terpenoids, sterols, polyketones, phenols, and acetylene aromatic compounds, which have shown anticancer, cytotoxic, anti-inflammatory, antimicrobial, and antiviral activities. The complex and diverse structural types, along with the diverse bioactivities, highlight the potential of Diatrypaceae as a valuable source of bioactive natural products. In this review, a deep analysis of the biosynthesis of pimarane diterpenes and scoparasin-type cytochalasins is provided, coupled with a compilation of the biosynthetic pathways of aromatic acetylene compounds in filamentous fungi. This comprehensive review not only enhances our understanding of the natural product chemistry, biological activities, and biosynthesis of secondary metabolites from the Diatrypaceae family but also promotes the exploitation and development of important bioactive compounds and potential strains.

Rare NRPS Gene Cluster for Desferriferrichrome Biosynthesis Controls the Conflict between Trap Formation and Nematicidal Activity in Arthrobotrys oligospora

The formation of the trapping device induced by nematodes has been assumed as an indicator for a switch from saprophytic to predacious lifestyles for nematode-trapping fungi. However, fungal nematocidal activity is not completely synonymous with fungal trap formation. We found that the predominant nematode-trapping fungus Arthrobotrys oligospora harbored a rare NRPS (Ao415) gene cluster that was mainly distributed in nematode-trapping fungi. The gene Ao415 putatively encodes a protein with a unique domain organization, distinct from other NRPSs in other fungi. Mutation of the two key biosynthetic genes Ao415 and Ao414 combined with nontarget metabolic analysis revealed that the Ao415 gene cluster was responsible for the biosynthesis of a hydroxamate siderophore, desferriferrichrome (1). Lack of desferriferrichrome (1) and its hydroxamate precursor (3) could lead to significantly increased Fe3+ content, which induced fungal trap formation without a nematode inducer. Furthermore, the addition of Fe3+ strongly improved fungal trap formation but deleteriously caused broken traps. The addition of 1 significantly attenuated trap formation but enhanced fungal nematicidal activity. Our findings indicate that iron is a key factor for trap formation and provide a new insight into the underlying mechanism of siderophores in nematode-trapping fungi.

Comparative Genomic Analysis and Metabolic Potential Profiling of a Novel Culinary-Medicinal Mushroom, Hericium rajendrae (Basidiomycota)

Hericium rajendrae is an emerging species in the genus Hericium with few members. Despite being highly regarded due to its rarity, knowledge about H. rajendrae remains limited. In this study, we sequenced, de novo assembled, and annotated the complete genome of H. rajendrae NPCB A08, isolated from the Qinling Mountains in Shaanxi, China, using the Illumina NovaSeq and Nanopore PromethION technologies. Comparative genomic analysis revealed similarities and differences among the genomes of H. rajendrae, H. erinaceus, and H. coralloides. Phylogenomic analysis revealed the divergence time of the Hericium genus, while transposon analysis revealed evolutionary characteristics of the genus. Gene family variation reflected the expansion and contraction of orthologous genes among Hericium species. Based on genomic bioinformation, we identified the candidate genes associated with the mating system, carbohydrate-active enzymes, and secondary metabolite biosynthesis. Furthermore, metabolite profiling and comparative gene clusters analysis provided strong evidence for the biosynthetic pathway of erinacines in H. rajendrae. This work provides the genome of H. rajendrae for the first time, and enriches the genomic content of the genus Hericium. These findings also facilitate the application of H. rajendrae in complementary drug research and functional food manufacturing, advancing the field of pharmaceutical and functional food production involving H. rajendrae.

Bioinformatic Analysis of Secondary Metabolite Biosynthetic Potential in Pathogenic Fusarium

Fusarium species are among the filamentous fungi with the most pronounced impact on agricultural production and human health. The mycotoxins produced by pathogenic Fusarium not only attack various plants including crops, causing various plant diseases that lead to reduced yields and even death, but also penetrate into the food chain of humans and animals to cause food poisoning and consequent health hazards. Although sporadic studies have revealed some of the biosynthetic pathways of Fusarium toxins, they are insufficient to satisfy the need for a comprehensive understanding of Fusarium toxin production. In this study, we focused on 35 serious pathogenic Fusarium species with available genomes and systematically analyzed the ubiquity of the distribution of identified Fusarium- and non-Fusarium-derived fungal toxin biosynthesis gene clusters (BGCs) in these species through the mining of core genes and the comparative analysis of corresponding BGCs. Additionally, novel sesterterpene synthases and PKS_NRPS clusters were discovered and analyzed. This work is the first to systematically analyze the distribution of related mycotoxin biosynthesis in pathogenic Fusarium species. These findings enhance the knowledge of mycotoxin production and provide a theoretical grounding for the prevention of fungal toxin production using biotechnological approaches.

In silico analyses of maleidride biosynthetic gene clusters

Maleidrides are a family of structurally related fungal natural products, many of which possess diverse, potent bioactivities. Previous identification of several maleidride biosynthetic gene clusters, and subsequent experimental work, has determined the 'core' set of genes required to construct the characteristic medium-sized alicyclic ring with maleic anhydride moieties. Through genome mining, this work has used these core genes to discover ten entirely novel putative maleidride biosynthetic gene clusters, amongst both publicly available genomes, and encoded within the genome of the previously un-sequenced epiheveadride producer Wicklowia aquatica CBS 125634. We have undertaken phylogenetic analyses and comparative bioinformatics on all known and putative maleidride biosynthetic gene clusters to gain further insights regarding these unique biosynthetic pathways.