Mycoviruses from Aspergillus fungi involved in fermentation of dried bonito.

Fungi are exploited for fermentation of foods such as cheese, Japanese sake, and soy sauce. However, the diversity of viruses that infect fungi involved in food fermentation is poorly understood. Fermented dried bonito ("katsuobushi") is one of the most important processed marine products in Japan.

Greetings from virologists to mycologists: A review outlining viruses that live in fungi.

Viruses are genetic elements that parasitize self-replicating cells. Therefore, organisms parasitized by viruses are not limited to animals and plants but also include microorganisms. Among these, viruses that parasitize fungi are known as mycoviruses.

Metagenomic Insights Reveal Unrecognized Diversity of Entotheonella in Japanese Theonella Sponges.

Numerous biologically active natural products have been discovered from marine sponges, particularly from Theonella swinhoei, which is known to be a prolific source of natural products such as polyketides and peptides. Recent studies have revealed that many of these natural products are biosynthesized by Candidatus Entotheonella phylotypes, which are uncultivated symbionts within T. swinhoei.

Identification of glycine betaine as a host-derived molecule required for the vegetative proliferation of the protozoan parasite .

is an industrially significant protozoan parasite of Manila clam, . So far, various media, based on Dulbecco's Modified Eagle Medium and Ham's F-12 nutrient mixture with supplementation of fetal bovine serum (FBS), have been developed to proliferate the parasitizing trophozoite stage of . The present study showed that did not proliferate in FBS-deficient Perkinsus broth medium (PBMΔF), but proliferated well in PBMΔF supplemented with tissue extract of host Manila clams, indicating that FBS and Manila clam tissue contained molecule(s) required for proliferation.

Interspecies Genomic Variation and Transcriptional Activeness of Secondary Metabolism-Related Genes in Section .

Filamentous fungi produce various bioactive compounds that are biosynthesized by sets of proteins encoded in biosynthesis gene clusters (BGCs). For an unknown reason, many BGCs are transcriptionally silent in laboratory conditions, which has hampered the discovery of novel fungal compounds. The transcriptional reactiveness of fungal secondary metabolism is not fully understood.

Structural Revision of Natural Cyclic Depsipeptide MA026 Established by Total Synthesis and Biosynthetic Gene Cluster Analysis.

A revised structure of natural 14-mer cyclic depsipeptide MA026, isolated from Pseudomonas sp. RtlB026 in 2002 was established by physicochemical analysis with HPLC, MS/MS, and NMR and confirmed by total solid-phase synthesis. The revised structure differs from that previously reported in that two amino acid residues, assigned in error, have been replaced.

Phenotypic and Molecular Biological Analysis of Polymycovirus AfuPmV-1M From : Reduced Fungal Virulence in a Mouse Infection Model.

The filamentous fungal pathogen is one of the most common causal agents of invasive fungal infection in humans; the infection is associated with an alarmingly high mortality rate. In this study, we investigated whether a mycovirus, named AfuPmV-1M, can reduce the virulence of in a mouse infection model. AfuPmV-1M has high sequence similarity to AfuPmV-1, one of the polymycovirus that is a capsidless four-segment double-stranded RNA (dsRNA) virus, previously isolated from the genome reference strain of , Af293.

Fungal mycelia and bacterial thiamine establish a mutualistic growth mechanism.

Exclusivity in physical spaces and nutrients is a prerequisite for survival of organisms, but a few species have been able to develop mutually beneficial strategies that allow them to co-habit. Here, we discovered a mutualistic mechanism between filamentous fungus, , and bacterium, The bacterial cells co-cultured with the fungus traveled along mycelia using their flagella and dispersed farther with the expansion of fungal colony, indicating that the fungal mycelia supply space for bacteria to migrate, disperse, and proliferate. Transcriptomic, genetic, molecular mass, and imaging analyses demonstrated that the bacteria reached the mycelial edge and supplied thiamine to the growing hyphae, which led to a promotion of hyphal growth.

Mycovirus-Induced Tenuazonic Acid Production in a Rice Blast Fungus .

Fungi are a rich source of natural products with biological activities. In this study, we evaluated viral effects on secondary metabolism of the rice blast fungus using an isolate of APU10-199A co-infected with three types of mycoviruses: a totivirus, a chrysovirus, and a partitivirus. Comparison of the secondary metabolite profile of APU10-199A with that of the strain lacking the totivirus and chrysovirus showed that a mycotoxin tenuazonic (TeA) acid was produced in a manner dependent on the mycoviruses.

The Revised Structure of the Cyclic Octapeptide Surugamide A.

Surugamides are a group of non-ribosomal peptides isolated from marine-derived Streptomyces. Surugamide A (1) and its closely related derivatives, surugamides B-E (2-5), are D-amino acid containing cyclic octapeptides with cathepsin B inhibitory activity. The D-isoleucine (Ile), the nonproteinogenic amino acid residue embedded in 1, is less common in natural peptides because a rare C-epimerization is required for its biosynthesis.

Diastereoselective Total Synthesis and Structural Confirmation of Surugamide F.

Surugamide F is a linear decapeptide (1) isolated along with the cyclic octapeptides surugamides A-E (2-6), from a marine-derived Streptomyces species. The linear peptide 1 is produced by two nonribosomal peptide synthetases (NRPSs) encoded in adjacent open reading frames, which are further flanked by an additional pair of NRPS genes responsible for the biosyntheses of the cyclic peptides 2-6. While the cyclic peptides 2-6 were identified to be cathepsin B inhibitors, the biological activity of the new metabolite 1 still remained unclear.

Total Synthesis of the Nonribosomal Peptide Surugamide B and Identification of a New Offloading Cyclase Family.

The cathepsin B inhibitor surugamide B (2), along with structurally related derivatives (A and C-E), has previously been isolated from the marine actinomycete Streptomyces sp. JAMM992. The biosynthetic genes are unexpectedly part of a cluster of four non-ribosomal peptide synthetase (NRPS) genes, two of which are responsible for the biosynthesis of the additional linear decapeptide surugamide F.

Dereplication of peptidic natural products through database search of mass spectra.

Peptidic natural products (PNPs) are widely used compounds that include many antibiotics and a variety of other bioactive peptides. Although recent breakthroughs in PNP discovery raised the challenge of developing new algorithms for their analysis, identification of PNPs via database search of tandem mass spectra remains an open problem. To address this problem, natural product researchers use dereplication strategies that identify known PNPs and lead to the discovery of new ones, even in cases when the reference spectra are not present in existing spectral libraries.

Biosynthetic Gene Cluster for Surugamide A Encompasses an Unrelated Decapeptide, Surugamide F.

Genome mining is a powerful method for finding novel secondary metabolites. In our study on the biosynthetic gene cluster for the cyclic octapeptides surugamides A-E (inhibitors of cathepsin B), we found a putative gene cluster consisting of four successive non-ribosomal peptide synthetase (NRPS) genes, surA, surB, surC, and surD. Prediction of amino acid sequence based on the NRPSs and gene inactivation revealed that surugamides A-E are produced by two NRPS genes, surA and surD, which were separated by two NRPS genes, surB and surC.

Surugamides A-E, cyclic octapeptides with four D-amino acid residues, from a marine Streptomyces sp.: LC-MS-aided inspection of partial hydrolysates for the distinction of D- and L-amino acid residues in the sequence.

Surugamides A-E (1-5), cyclic octapeptides with four D-amino acid residues, were isolated from the broth of marine-derived Streptomyces sp. Their planar structures were determined by analyses of spectroscopic data, and the absolute configuration of constituent amino acid residues was determined by the Marfey's method. Differentiation of D-Ile and L-Ile in the sequence was established by chiral analysis of fragment peptides obtained from the partial hydrolysate, whose identification was conducted by LC-MS/MS.