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Endophytic fungi are increasingly being recognized for their diverse metabolites that may exhibit antimicrobial properties. In our study, we isolated seven endophytic fungal strains from Calea pinnatifida, which were identified as Hypomontagnella barbarensis, Neopestalotiopsis clavispora, Nigrospora sacchari-officinarum, Annulohypoxylon moriforme, Colletotrichum siamense, and Colletotrichum karstii (with two isolates from the same species). Furthermore, the antimicrobial activity of the extracts was assessed, revealing that the extract from Hypomontagnella barbarensis demonstrated activity against Staphylococcus aureus. Further investigation of secondary metabolites, employing UHPLC-HR-ESI-MS/MS in combination with molecular networking, facilitated annotation of the nine compounds. Of these, five were identified based on matches with the GNPS spectral library, and four were predicted based on the molecular network. Notably, from the extract of Hypomontagnella barbarensis, two pairs of diastereoisomeric acyl-tetronic acid derivatives were isolated and characterized using MS and NMR spectroscopy. This study highlights the potential of endophytic fungi as a valuable source of novel antimicrobial agents. [ABSTRACT FROM AUTHOR]

Stress management is an adaptive advantage for survival in adverse environments. Pathogens face this challenge during host colonization, requiring an appropriate stress response to establish infection. The fungal pathogen Cryptococcus neoformans undergoes thermal, oxidative, and osmotic stresses in the environment and animal host. Signaling systems controlled by Ras1, Hog1, and calcineurin respond to high temperatures and osmotic stress. Cationic stress caused by Na+, K+, and Li+ can be overcome with glycerol, the preferred osmolyte. Deleting the glycerol phosphate phosphatase gene (GPP2) prevents cells from accumulating glycerol due to a block in the last step of its biosynthetic pathway. Gpp2 accumulates in a phosphorylated form in a cna1Δ strain, and a physical interaction between Gpp2 and Cna1 was found; moreover, the gpp2Δ strain undergoes slow growth and has attenuated virulence in animal models of infection. We provide biochemical evidence that growth in 1 M NaCl increases glycerol content in the wild type, whereas gpp2Δ, cna1Δ, and cnb1Δ mutants fail to accumulate it. The deletion of cnb1Δ or cna1Δ renders yeast cells sensitive to cationic stress, and the Gfp-Gpp2 protein assumes an abnormal localization. We suggest a mechanism in which calcineurin controls Gpp2 at the post-translational level, affecting its localization and activity, leading to glycerol biosynthesis. Also, we showed the transcriptional profile of glycerol-deficient mutants and established the cationic stress response mediated by calcineurin; among the biological processes differentially expressed are carbon utilization, translation, transmembrane transport, glutathione metabolism, oxidative stress response, and transcription regulation. To our knowledge, this is the first time that this transcriptional profile has been described. These results have implications for pathogen stress adaptability. [ABSTRACT FROM AUTHOR]

Many small G proteins require post-translational modification to allow functional association to the cell membrane. This process often involves the enzymic addition of hydrophobic prenyl groups to a conserved cysteine residue near the C-terminus of the protein. The enzymes that catalyse these reactions include protein farnesyltransferase and protein geranylgeranyltransferases. The human fungal pathogen Cryptococcus neoformans requires functional Ras and Rho proteins in order to undergo normal growth and differentiation. Since farnesylation and geranylgeranylation are likely required for the proper function of these small G proteins, we hypothesized that inhibition of these prenylation events would alter the growth and cellular morphogenesis of this fungus. We cloned the RAM1 gene encoding the single protein-famesyltransferase [beta]-chain homologue in C. neoformans. Using a gene-disruption strategy in a diploid C. neoformans strain, we demonstrated that this gene encodes an essential function, in contrast to the case in Saccharomyces cerevisiae, in which the homologous RAM1 gene is not essential for growth. Pharmacological inhibition of farnesyltransferase activity resulted in dose-dependent cytostasis of C. neoformans, as well as prevention of hyphal differentiation. Simultaneous inhibition of farnesylation and calcineurin signalling results in a synthetic effect on growth. Protein farnesylation is required for the growth and cellular differentiation of C. neoformans and may provide novel targets for antifungal therapy.

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Reverse transcriptase polymerase chain reaction and magnetic capture techniques were employed in the quantification of the transcripts of cellobiohydrolase and cellobiose dehydrogenase in Phanerochaete chrysosporium-colonized wood chips. The transcript patterns were found to be markedly different from that formerly observed on defined media supplemented with glucose or cellulose. Transcripts of some lignin peroxidase and manganese peroxidase genes were also observed in the wood chips.

The chemical composition and antimicrobial activity of essential oils obtained from three Brazilian plant species-leaves and branches of Eremanthus erythropappus (Asteraceae), leaves of Plectranthus barbatus, and leaves of P. amboinicus (Lamiaceae)-were determined. Analysis by GC/MS and determination of Kovats indexes both indicated δ-elemene (leaves-42.61% and branches-23.41%) as well as (-)-α-bisabolol (leaves-24.80% and stem bark-66.16%) as major constituents of E. erythropappus essential oils. The main components of leaves of P. barbatus were identified as (Z)-caryophyllene (17.98%), germacrene D (17.35%), and viridiflorol (14.13%); whereas those of leaves of P. amboinicus were characterized as p-cymene (12.01%), γ-terpinene (14.74%), carvacrol (37.70%), and (Z)-caryophyllene (14.07%). The antimicrobial activity against yeasts and bacteria was assessed in broth microdilution assays to determine the minimum inhibitory concentration (MIC) necessary to inhibit microbial growth. In addition, the crude oil of branches of E. erythropappus was subjected to chromatographic separation procedures to afford purified (-)-α-bisabolol. This compound displayed biological activity against pathogenic yeasts, thus suggesting that the antimicrobial effect observed with crude oils of E. erythropappus leaves and branches may be related to the occurrence of (-)-α-bisabolol as their main component. Our results showed that crude oils of Brazilian plants, specifically E. erythropappus, P. barbatus, and P. amboinicus and its components, could be used as a tool for the developing novel and more efficacious antimicrobial agents. [ABSTRACT FROM AUTHOR]

Bioactivity-guided fractionation of an antimicrobial active extract from twigs of Baccharis retusa C. DC. (Asteraceae) yielded the flavanone 5,4'-dihydroxy-7-methoxyflavanone (sakuranetin) as responsible for the detected activity. The structure of the bioactive compound was established on the basis of spectroscopic data analysis, including NMR and MS. Additionally, the structure of a new crystal form of sakuranetin was confirmed by X-ray diffratometry. The minimum inhibitory concentrations (MIC) of isolated compound were determined against pathogenic yeast belonging to the genus Candida (six species), Cryptococcus (two species/four serotypes) and S. cerevisiae BY 4742 (S288c background) and ranged from 0.32 to 0.63 μg/μL. Our results showed that sakuranetin, which structure was fully characterized, could be used as a tool for the design of novel and more efficacious antifungal agents. [ABSTRACT FROM AUTHOR]

Saccharomyces cerevisiae Ste12p plays a key role in coupling signal transduction through MAP kinase modules to cell-specific or morphogenesis-specific gene expression required for mating and pseudohyphal (PH)/filamentous growth (FG). Ste12p homologues in the pathogenic yeasts Candida albicans and Filobasidiela neoformans apparently play similar roles during dimorphic transitions. Here we report the isolation and characterization of the first Ste12 protein from a true filamentous fungus. Aspergillus nidulans steA encodes a protein with a homeodomain 63-75% identical to those of other Ste12 proteins, with greatest similarity to FnSte12αp. SteAp and Ste12αp lack the pheromone induction domain found in budding yeast Ste12p, but have C-terminal C[sub 2]/H[sub 2]-Zn[sup +2] finger domains not present in the other Ste12 proteins. A ΔsteA strain is sterile and differentiates neither ascogenous tissue nor fruiting bodies (cleistothecia). However, the development of sexual cycle-specific Hülle cells is unaffected. Filamentous growth, conidiation and the differentiation of PH-like asexual reproductive cells (metulae and phialides) are normal in the deletion strain. Northern analysis of key regulators of the asexual and sexual reproductive cycles support the observation that although SteAp function is restricted to the sexual cycle, cross regulation between the two developmental pathways exists. Our results further suggest that while several classes of related proteins control similar morphogenetic events in A. nidulans and the dimorphic yeasts, significant differences must exist in the regulatory circuitry. [ABSTRACT FROM AUTHOR]