Proteinases and exopeptidases from the phytopathogenic fungusUstilago maydis

Nonanol, an Induced Biomolecule Produced by Bacillus atrophaeus NMB01 During Interaction With Phytophthora infestans Can be Explored as a Novel Formulation for the Management of Late Blight of Potatoes

Phytophthora infestans, the pathogen responsible for late blight, continues to pose a significant risk to worldwide potato cultivation, including its historical impact during the Irish Potato Famine. Traditional management relies heavily on synthetic fungicides, but their prolonged use has led to fungicide resistance and environmental concerns. This study examines the potential of the bacterial endophyte Bacillus atrophaeus NMB01 as a biocontrol agent against P. infestans. Six biomolecules produced by B. atrophaeus NMB01 were docked against 15 P. infestans protein targets, with 1-nonanol, glafenine hydrochloride, and mucic acid showing high binding affinity. Wet lab assays confirmed that 1-nonanol inhibited P. infestans mycelial growth by 78% at 2 ppm. Molecular dynamics simulations validated the stability of these interactions. A tri-trophic interaction study identified additional volatile and non-volatile organic compounds (VOCs/NVOCs), with minocycline and doxazosin exhibiting strong binding across all targets. Transcriptome analysis of P. infestans exposed to 1-nonanol revealed differential gene expression, with upregulated genes linked to stress responses and downregulated genes, such as TAR1, cysteine synthase, and glutathione transferase, presenting novel antifungal targets. This study highlights 1-nonanol as a promising eco-friendly alternative to conventional fungicides, offering a sustainable solution for managing late blight and advancing potato cultivation resilience.

Leucoagaricus gongylophorus uses leaf-cutting ants to vector proteolytic enzymes towards new plant substrate

The mutualism between leaf-cutting ants and their fungal symbionts revolves around processing and inoculation of fresh leaf pulp in underground fungus gardens, mediated by ant fecal fluid deposited on the newly added plant substrate. As herbivorous feeding often implies that growth is nitrogen limited, we cloned and sequenced six fungal proteases found in the fecal fluid of the leaf-cutting ant Acromyrmex echinatior and identified them as two metalloendoproteases, two serine proteases and two aspartic proteases. The metalloendoproteases and serine proteases showed significant activity in fecal fluid at pH values of 5-7, but the aspartic proteases were inactive across a pH range of 3-10. Protease activity disappeared when the ants were kept on a sugar water diet without fungus. Relative to normal mycelium, both metalloendoproteases, both serine proteases and one aspartic protease were upregulated in the gongylidia, specialized hyphal tips whose only known function is to provide food to the ants. These combined results indicate that the enzymes are derived from the ingested fungal tissues. We infer that the five proteases are likely to accelerate protein extraction from plant cells in the leaf pulp that the ants add to the fungus garden, but regulatory functions such as activation of proenzymes are also possible, particularly for the aspartic proteases that were present but without showing activity. The proteases had high sequence similarities to proteolytic enzymes of phytopathogenic fungi, consistent with previous indications of convergent evolution of decomposition enzymes in attine ant fungal symbionts and phytopathogenic fungi.

The intracellular proteolytic system of Yarrowia lipolytica and characterization of an aminopeptidase

Intracellular proteases of Yarrowia lipolytica have been scarcely studied. These enzymes may play an important role in nitrogen metabolism, posttranslational processing, nutritional stress, dimorphism, etc.; biochemical and genetic control of these enzymes can help in obtaining high-level expression of recombinant proteins in heterologous systems. In this study, we report the presence of three proteases: aminopeptidase yylAPE, carboxypeptidase yylCP and dipeptidyl aminopeptidase yylDAP, measured under several nutritional conditions. Yarrowia lipolytica produced the highest level of intracellular proteolytic enzymes, i.e. yylAPE, yylCP and yylDAP, in media with peptone during stationary growth phase. When soluble extracts were subjected to PAGE, and the three activities were revealed in gels with the corresponding substrates, only one band of activity was detected for each one. The three enzymes were affected by serine protease inhibitors. Chelating agents affected mainly APE activity. The aminopeptidase was purified by selective fractionation with ammonium sulfate and three chromatographic steps (anion exchange, hydrophobic interaction and gel filtration chromatography). The enzyme had a molecular mass of 97 kDa; optimal pH and temperature were 7.0 and 37 degrees C, respectively. The aminopeptidase showed a preference for lysine in the N-position. The K(m) value was 0.86 microM and V(max) value was 990.8 micromoL min(-1) mg(-1) for Lys-pNA.

Purification and characterization of an intracellular aspartyl acid proteinase (pumAi) fromUstilago maydis

The intracellular proteinase pumAi in Ustilago maydis has been associated with yeast-mycelium dimorphic transition. The proteinase was purified from a cell-free extract by ammonium sulfate fractionation and chromatographic steps including hydrophobic interactions on a Phenyl Superose column, ion exchange on a Mono Q column, and gel filtration on Superose 12 columns. The enzyme has a mass of 35.3–36.6 kDa, a pH and temperature optimum of 4.0 and 40 °C, respectively, and a pI of 5.5. The enzyme degraded hemoglobin, gelatin, albumin, and casein, but not collagen, and the enzymatic activity was strongly inhibited by pepstatin A, an aspartyl proteinase-specific inhibitor. The biochemical characteristics of pumAi are similar to other fungal intracellular aspartyl proteinases, however, this is the first biochemical characterization of a basidiomycete proteinase probably associated with dimorphic yeast-mycelium transition.Key words: aspartyl proteinase, yeast-mycelium transition, Ustilago maydis.