Project description:BackgroundPerylenequinones from Shiraia fruiting bodies are excellent photosensitizers and widely used for anti-cancer photodynamic therapy (PDT). The lower yield of Shiraia perylenequinones becomes a significant bottleneck for their medical application. Branched-chain amino acids (BCAAs) not only serve as important precursors for protein synthesis, but also are involved in signaling pathway in cell growth and development. However, there are few reports concerning their regulation of fungal secondary metabolism. In present study, the eliciting effects of BCAAs including L-isoleucine (L-Ile), L-leucine (L-Leu) and L-valine (L-Val) on Shiraia perylenequinone production were investigated.ResultsBased on the analysis of the transcriptome and amino acid contents of Shiraia in the production medium, we revealed the involvement of BCAAs in perylenequinone biosynthesis. The fungal conidiation was promoted by L-Val treatment at 1.5 g/L, but inhibited by L-Leu. The spore germination was promoted by both. The production of fungal perylenequinones including hypocrellins A (HA), HC and elsinochromes A-C (EA-EC) was stimulated significantly by L-Val at 1.5 g/L, but sharply suppressed by L-Leu. After L-Val treatment (1.5 g/L) in Shiraia mycelium cultures, HA, one of the main bioactive perylenequinones reached highest production 237.92 mg/L, about 2.12-fold than that of the control. Simultaneously, we found that the expression levels of key genes involved in the central carbon metabolism and in the late steps for perylenequinone biosynthesis were up-regulated significantly by L-Val, but most of them were down-regulated by L-Leu.ConclusionsOur transcriptome analysis demonstrated that BCAA metabolism was involved in Shiraia perylenequinone biosynthesis. Exogenous BCAAs exhibit contrasting effects on Shiraia growth and perylenequinones production. L-Val could promote perylenequinone biosynthesis via not only enhancing the central carbon metabolism for more precursors, but also eliciting perylenequinone biosynthetic gene expressions. This is the first report on the regulation of BCAAs on fungal perylenequinone production. These findings provided a basis for understanding physiological roles of BCAAs and a new avenue for increasing perylenequinone production in Shiraia mycelium cultures.
Project description:BackgroundFungal perylenequinonoid (PQ) pigments from Shiraia fruiting body have been well known as excellent photosensitizers for medical and agricultural uses. The fruiting bodies are colonized by a diverse bacterial community of unknown function. We screened the companion bacteria from the fruiting body of Shiraia sp. S9 and explored the bacterial elicitation on fungal PQ production.ResultsA bacterium Pseudomonas fulva SB1 isolated from the fruiting body was found to stimulate the production of fungal PQs including hypocrellins A, C (HA and HC), and elsinochromes A-C (EA, EB and EC). After 2 days of co-cultures, Shiraia mycelium cultures presented the highest production of HA (325.87 mg/L), about 3.20-fold of that in axenic culture. The co-culture resulted in the induction of fungal conidiation and the formation of more compact fungal pellets. Furthermore, the bacterial treatment up-regulated the expression of polyketide synthase gene (PKS), and activated transporter genes of ATP-binding cassette (ABC) and major facilitator superfamily transporter (MFS) for PQ exudation.ConclusionsWe have established a bacterial co-culture with a host Shiraia fungus to induce PQ biosynthesis. Our results provide a basis for understanding bacterial-fungal interaction in fruiting bodies and a practical co-culture process to enhance PQ production for photodynamic therapy medicine.
Project description:BackgroundFungal perylenequinones (PQs) are a class of photoactivated polyketide mycotoxins produced by plant-associated fungi. Hypocrellins, the effective anticancer photodynamic therapy (PDT) agents are main bioactive PQs isolated from a bambusicolous Shiraia fruiting bodies. We found previously that bacterial communities inhabiting fungal fruiting bodies are diverse, but with unknown functions. Bacillus is the most dominant genus inside Shiraia fruiting body. To understand the regulation role of the dominant Bacillus isolates on host fungus, we continued our work on co-culture of the dominant bacterium B. cereus No.1 with host fungus Shiraia sp. S9 to elucidate bacterial regulation on fungal hypocrellin production.ResultsResults from "donut" plate tests indicated that the bacterial culture could promote significantly fungal PQ production including hypocrellin A (HA), HC and elsinochrome A-C through bacterial volatiles. After analysis by gas chromatograph/mass spectrometer and confirmation with commercial pure compounds, the volatiles produced by the bacterium were characterized. The eliciting roles of bacterial volatile organic compounds (VOCs) on HA production via transcriptional regulation of host Shiraia fungus were confirmed. In the established submerged bacterial volatile co-culture, bacterial volatiles could not only promote HA production in the mycelium culture, but also facilitate the release of HA into the medium. The total production of HA was reached to 225.9 mg/L, about 1.87 times that of the fungal mono-culture. In contrast, the live bacterium suppressed markedly fungal PQ production in both confrontation plates and mycelium cultures by direct contact. The live bacterium not only down-regulated the transcript levels of HA biosynthetic genes, but also degraded extracellular HA quickly to its reductive product.ConclusionOur results indicated that bacterial volatile release could be a long-distance signal to elicit fungal PQ production. Biodegradation and inhibition by direct contact on fungal PQs were induced by the dominate Bacillus to protect themselves in the fruiting bodies. This is the first report on the regulation of Bacillus volatiles on fungal PQ production. These findings could be helpful for both understanding the intimate fungal-bacterial interactions in a fruiting body and establishing novel cultures for the enhanced production of bioactive PQs.
Project description:Shiraia mycelial culture is a promising biotechnological alternative for the production of hypocrellin A (HA), a new photosensitizer for anticancer photodynamic therapy (PDT). The extractive fermentation of intracellular HA in the nonionic surfactant Triton X-100 (TX100) aqueous solution was studied in the present work. The addition of 25 g/L TX100 at 36 h of the fermentation not only enhanced HA exudation to the broth by 15.6-fold, but stimulated HA content in mycelia by 5.1-fold, leading to the higher production 206.2 mg/L, a 5.4-fold of the control on day 9. After the induced cell membrane permeabilization by TX100 addition, a rapid generation of nitric oxide (NO) and hydrogen peroxide (H2O2) was observed. The increase of NO level was suppressed by the scavenger vitamin C (VC) of reactive oxygen species (ROS), whereas the induced H2O2 production could not be prevented by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), suggesting that NO production may occur downstream of ROS in the extractive fermentation. Both NO and H2O2 were proved to be involved in the expressions of HA biosynthetic genes (Mono, PKS and Omef) and HA production. NO was found to be able to up-regulate the expression of transporter genes (MFS and ABC) for HA exudation. Our results indicated the integrated role of NO and ROS in the extractive fermentation and provided a practical biotechnological process for HA production.
Project description:Shiraia bambusicola has been used as a traditional Chinese medicine for a long history. Its major medicinal active metabolites are perylenequinones, including hypocrellin A, elsinochrome A and so on. At present, the fermentation yield of perylenequinones is low, and its complex biosynthesis and regulatory pathways are still unclear. In this study, nitric oxide, as a downstream signal molecule of hydrogen peroxide, regulates the biosynthesis of perylenequinones. Exogenous addition of 0.01 mM sodium nitroprusside (nitric oxide donor) can promote perylenequinones production by 156% compared with the control. Further research found that hydrogen peroxide and nitric oxide increased the transcriptional level of the biosynthetic genes of hypocrellin A. The results showed that nitric oxide is involved in the biosynthesis and regulation of perylenequinones in Shiraia bambusicola as a signal molecule. In the future, the yield of perylenequinones can be increased by adding exogenous nitric oxide in fermentation.
Project description:The formation of biofilms is closely associated with persistent and chronic infections, and physiological heterogeneity such as pH and oxygen gradients renders biofilms highly resistant to conventional antibiotics. To date, effectively treating biofilm infections remains a significant challenge. Herein, we report the fabrication of micellar nanoparticles adapted to heterogeneous biofilm microenvironments, enabling nitric oxide (NO) release through two distinct photoredox catalysis mechanisms. The key design feature involves the use of tertiary amine (TA) moieties, which function as sacrificial agents to avoid the quenching of photocatalysts under normoxic and neutral pH conditions and proton acceptors at acidic pH to allow deep biofilm penetration. This biofilm-adaptive NO-releasing platform shows excellent antibiofilm activity against ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) biofilms both in vitro and in a mouse skin infection model, providing a strategy for combating biofilm heterogeneity and biofilm-related infections.
Project description:Consumption of L-arginine contributes to reduced bioavailability of nitric oxide (NO) that is critical for the development of ischemia-reperfusion injury. The aim of the study was to determine myocardial arginase expression and activity in ischemic-reperfusion myocardium and whether local inhibition of arginase within the ischemic myocardium results in increased NO production and protection against myocardial ischemia-reperfusion. Anesthetized pigs were subjected to coronary artery occlusion for 40 min followed by 4 h reperfusion. The pigs were randomized to intracoronary infusion of vehicle (n = 7), the arginase inhibitor N-hydroxy-nor-L-arginine (nor-NOHA, 2 mg/min, n = 7), the combination of nor-NOHA and the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 0.35 mg/min, n = 6) into the jeopardized myocardial area or systemic intravenous infusion of nor-NOHA (2 mg/min, n = 5) at the end of ischemia and start of reperfusion. The infarct size of the vehicle group was 80 ± 4% of the area at risk. Intracoronary nor-NOHA reduced infarct size to 46 ± 5% (P<0.01). Co-administration of L-NMMA abrogated the cardioprotective effect mediated by nor-NOHA (infarct size 72 ± 6%). Intravenous nor-NOHA did not reduce infarct size. Arginase I and II were expressed in cardiomyocytes, endothelial, smooth muscle and poylmorphonuclear cells. There was no difference in cytosolic arginase I or mitochondrial arginase II expression between ischemic-reperfused and non-ischemic myocardium. Arginase activity increased 2-fold in the ischemic-reperfused myocardium in comparison with non-ischemic myocardium. In conclusion, ischemia-reperfusion increases arginase activity without affecting cytosolic arginase I or mitochondrial arginase II expression. Local arginase inhibition during early reperfusion reduces infarct size via a mechanism that is dependent on increased bioavailability of NO.
Project description:Nitric oxide (NO) at a high concentration is an effector to kill pathogens during insect immune responses, it also functions as a second messenger at a low concentration to regulate antimicrobial peptide (AMP) production in insects. Drosophila calcineurin subunit CanA1 is a ubiquitous serine/threonine protein phosphatase involved in NO-induced AMP production. However, it is unclear how NO regulates AMP expression. In this study, we used a lepidopteran pest Ostrinia furnacalis and Drosophila S2 cells to investigate how NO signaling affects the AMP production. Bacterial infections upregulated the transcription of nitric oxide synthase 1/2 (NOS1/2), CanA and AMP genes and increased NO concentration in larval hemolymph. Inhibition of NOS or CanA activity reduced the survival of bacteria-infected O. furnacalis. NO donor increased NO level in plasma and upregulated the production of CanA and certain AMPs. In S2 cells, killed Escherichia coli induced NOS transcription and boosted NO production, whereas knockdown of NOS blocked the NO level increase caused by E. coli. As in O. furnacalis larvae, supplementation of the NO donor increased NO level in the culture medium and AMP expression in S2 cells. Suppression of the key pathway genes showed that the IMD (but not Toll) pathway was involved in the upregulation of CecropinA1, Defensin, Diptericin, and Drosomycin by killed E. coli. Knockdown of NOS also reduced the expression of CanA1 and AMPs induced by E. coli, indicative of a role of NO in the AMP expression. Furthermore, CanA1 RNA interference and inhibition of its phosphatase activity significantly reduced NO-induced AMP expression, and knockdown of IMD suppressed NO-induced AMP expression. Together, these results suggest that NO-induced AMP production is mediated by CanA1 via the IMD pathway.
Project description:BackgroundNitric oxide (NO) is a ubiquitous signaling mediator in various physiological processes. However, there are less reports concerning the effects of NO on fungal secondary metabolites. Hypocrellins are effective anticancer photodynamic therapy (PDT) agents from fungal perylenequinone pigments of Shiraia. NO donor sodium nitroprusside (SNP) was used as a chemical elicitor to promote hypocrellin biosynthesis in Shiraia mycelium cultures.ResultsSNP application at 0.01-0.20 mM was found to stimulate significantly fungal production of perylenequinones including hypocrellin A (HA) and elsinochrome A (EA). SNP application could not only enhance HA content by 178.96% in mycelia, but also stimulate its efflux to the medium. After 4 days of SNP application at 0.02 mM, the highest total production (110.34 mg/L) of HA was achieved without any growth suppression. SNP released NO in mycelia and acted as a pro-oxidant, thereby up-regulating the gene expression and activity of reactive oxygen species (ROS) generating NADPH oxidase (NOX) and antioxidant enzymes, leading to the increased levels of superoxide anion (O2-) and hydrogen peroxide (H2O2). Gene ontology (GO) analysis revealed that SNP treatment could up-regulate biosynthetic genes for hypocrellins and activate the transporter protein major facilitator superfamily (MFS) for the exudation. Moreover, SNP treatment increased the proportion of total unsaturated fatty acids in the hypha membranes and enhanced membrane permeability. Our results indicated both cellular biosynthesis of HA and its secretion could contribute to HA production induced by SNP.ConclusionsThe results of this study provide a valuable strategy for large-scale hypocrellin production and can facilitate further understanding and exploration of NO signaling in the biosynthesis of the important fungal metabolites.
Project description:Shear stress generated by distinct blood flow patterns modulates endothelial cell phenotype to spatially restrict atherosclerotic plaque development. Signaling through p21-activated kinase (PAK) mediates several of the deleterious effects of shear stress, including enhanced NF-?B activation and proinflammatory gene expression. Whereas shear stress activates PAK in endothelial cells on a fibronectin matrix, basement membrane proteins limit shear-induced PAK activation and inflammation through a protein kinase A-dependent pathway; however, the mechanisms underlying this regulation were unknown. We show that basement membrane proteins limit membrane recruitment of PAK2, the dominant isoform in endothelial cells, by blocking its interaction with the adaptor protein Nck. This uncoupling response requires protein kinase A-dependent nitric oxide production and subsequent PAK2 phosphorylation on Ser-20 in the Nck-binding domain. Of importance, shear stress does not stimulate nitric oxide production in endothelial cells on fibronectin, resulting in enhanced PAK activation, NF-?B phosphorylation, ICAM-1 expression, and monocyte adhesion. These data demonstrate that differential flow-induced nitric oxide production regulates matrix-specific PAK signaling and describe a novel mechanism of nitric oxide-dependent NF-?B inhibition.