The Pseudomonas Quinolone Signal (PQS): Not Just for Quorum Sensing Anymore

The Pseudomonas quinolone signal (PQS) has been studied primarily in the context of its role as a quorum-sensing signaling molecule. Recent data suggest, however, that this molecule may also function to mediate iron acquisition, cytotoxicity, outer-membrane vesicle biogenesis, or to exert host immune modulatory activities

Comparative analysis of the secretomes of Schizophyllum commune and other wood-decay basidiomycetes during solid-state fermentation reveals its unique lignocellulose-degrading enzyme system

Additional file 3: Table S2. Identified proteins in the secretomes of four fungi during SSF on Jerusalem artichoke stalk

Functions of the Clostridium acetobutylicium FabF and FabZ proteins in unsaturated fatty acid biosynthesis

<p>Abstract</p> <p>Background</p> <p>The original anaerobic unsaturated fatty acid biosynthesis pathway proposed by Goldfine and Bloch was based on in <it>vivo </it>labeling studies in <it>Clostridium butyricum </it>ATCC 6015 (now <it>C. beijerinckii</it>) but to date no dedicated unsaturated fatty acid biosynthetic enzyme has been identified in Clostridia. <it>C. acetobutylicium </it>synthesizes the same species of unsaturated fatty acids as <it>E. coli</it>, but lacks all of the known unsaturated fatty acid synthetic genes identified in <it>E. coli </it>and other bacteria. A possible explanation was that two enzymes of saturated fatty acid synthesis of <it>C. acetobutylicium</it>, FabZ and FabF might also function in the unsaturated arm of the pathway (a FabZ homologue is known to be an unsaturated fatty acid synthetic enzyme in enterococci).</p> <p>Results</p> <p>We report that the FabF homologue located within the fatty acid biosynthetic gene cluster of <it>C. acetobutylicium </it>functions in synthesis of both unsaturated fatty acids and saturated fatty acids. Expression of this protein in <it>E. coli </it>functionally replaced both the FabB and FabF proteins of the host in <it>vivo </it>and replaced <it>E. coli </it>FabB in a defined in <it>vitro </it>fatty acid synthesis system. In contrast the single <it>C. acetobutylicium </it>FabZ homologue, although able to functionally replace <it>E. coli </it>FabZ in <it>vivo </it>and in <it>vitro</it>, was unable to replace FabA, the key dehydratase-isomerase of <it>E. coli </it>unsaturated fatty acid biosynthesis in <it>vivo </it>and lacked isomerase activity in <it>vitro</it>.</p> <p>Conclusion</p> <p>Thus, <it>C. acetobutylicium </it>introduces the double of unsaturated fatty acids by use of a novel and unknown enzyme.</p

Change in physics-chemical properties of casein after treated by ultrasound

Casein was subjected to ultrasound treatment by means of 160 W (USC-1) and 400 W (USC-2) in the present research. Effect of ultrasound treatment on physics-chemical properties of casein protein was investigated. Casein proteins were degraded into the peptides with low molecular weight due to ultrasound treatment according to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Significant (P &lt; 0.05) improvement in solubility of USC-1 and USC-2 in water and 0.1 M NaCl was found compared with the native casein. The heat stability of casein also increased after treating by ultrasound. Moreover, the obvious change in emulsifying activity and emulsion stability of ultrasound-treated casein was found

Artificial Neural Network for Production of Antioxidant Peptides Derived from Bighead Carp Muscles with Alcalase

Kontrolirani enzimski modificirani proteini koriste se kao dobri izvori bioaktivnih sastojaka proteina, a hidrolizati iz mišića pjegavog šarana mogu se upotrijebiti kao antioksidansi u kontroliranim uvjetima. Antioksidativna sposobnost je procijenjena prema sposobnosti uklanjanja slobodnih radikala DPPH × , OH × i O2 × . Zbog robusnosti, tolerancije na greške, velike brzine računanja i mogućnosti samoučenja, umjetna neuronska mreža može se upotrijebiti za simulaciju modela i optimiranje varijabli hidrolize: pH-vrijednosti, temperature, vremena hidrolize, omjera mišića i vode, te omjera enzima i supstrata (E/S) za proizvodnju antioksidativnih peptida. Postignuti su optimalni uvjeti za postizanje maksimalne antioksidativne sposobnosti. Hidrolizati koji su učinkovito uklonili DPPH×, OH× i O2 × radikale hidrolizirani su nakon 4,8 sata pri aktivnosti alkalaze od 4,8 AU/kg i omjeru mišića/vode od 1:1,9; za 6 sati pri 3,84 AU/kg i omjeru od 1:1,4; te za 4,3 sata pri 4,8 AU/kg i omjeru mišića/vode od 1:1; pri pH-vrijednosti od 7,5 i 60 °C. Ovo je istraživanje potvrdilo da se umjetna neuronska mreža može upotrijebiti za simulaciju reakcije te predviđanje uvjeta hidrolize pri kojima hidrolizati pokazuju najveću sposobnost uklanjanja slobodnih radikala DPPH × , OH × i O2 × .Controlled enzymatic modification proteins are currently being used as good sources of bioactive protein ingredients, and hydrolysates derived from bighead carp muscles may serve as antioxidants through the control of the processing-related parameters. The antioxidant ability was evaluated with regard to the scavenging effect on free radical DPPH·, OH· and O2 ·–. Due to the robustness, fault tolerance, high computational speed and self--learning ability, artificial neural network (ANN) can be employed to build a predictive model for hydrolysis and optimize the hydrolysis variables: pH, temperature, hydrolysis time, muscle/water ratio and enzyme/substrate ratio (E/S) for the production of antioxidant peptides. Optimum conditions to achieve the maximum antioxidant ability were obtained. The hydrolysates, which scavenged most effectively the DPPH·, OH· and O2 ·–, were hydrolyzed for 4.8 h with an activity of alcalase of 4.8 AU/kg, for 6 h with 3.84 AU/kg and for 4.3 h with 4.8 AU/kg, at pH=7.5 and 60 °C. Their respective muscle/water ratio was 1:1.9, 1:1.4 and 1:1. The present study confirmed that ANN could be used to simulate the hydrolysis process and predict hydrolysis conditions under which the hydrolysates could show the most effective scavenging ability on DPPH·, OH· and O2 ·–

Effect of ε-Poly-L-lysine on Postharvest Diseases and Disease-Resistant Substance Metabolism in Passion Fruits

In order to investigate the inhibitory effect of ε-poly-L-lysine (ε-PL) on the occurrence of Lasiodiplodia theobromae-induced diseases and its correlation with disease resistance in postharvest passion fruits, harvested golden passion fruits (cv. Fujian Baixiangguo 3) were immersed in either sterile distilled water (as control group) or 100 mg/L ε-PL solution for 10 min, inoculated with L. theobromae, and stored at (28 ± 1) ℃ and 90% relative humidity for up to 7 days. The changes of fruit lesion diameter, cell membrane permeability, lignin content and disease resistance-related enzyme activities in the pericarp were assayed every day. The results showed that compared to the control group, ε-PL delayed the increase in cell membrane permeability and lesion diameter, and enhanced the content of lignin and the activities of disease resistance-related enzymes including cinnamate-4-hydroxylase (C4H), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), peroxidase (POD), β-1,3-glucanase (GLU), 4-coumarate CoA ligase (4-CL), chitinase (CHI) and cinnamyl alcohol dehydrogenase (CAD), thereby maintaining cell membrane integrity by delaying the increase of cell membrane permeability, enhancing disease resistance, and inhibiting the occurrence of L. theobromae-induced diseases in harvested passion fruits

Cell-Type Independent MYC Target Genes Reveal a Primordial Signature Involved in Biomass Accumulation

The functions of key oncogenic transcription factors independent of context have not been fully delineated despite our richer understanding of the genetic alterations in human cancers. The MYC oncogene, which produces the Myc transcription factor, is frequently altered in human cancer and is a major regulatory hub for many cancers. In this regard, we sought to unravel the primordial signature of Myc function by using high-throughput genomic approaches to identify the cell-type independent core Myc target gene signature. Using a model of human B lymphoma cells bearing inducible MYC, we identified a stringent set of direct Myc target genes via chromatin immunoprecipitation (ChIP), global nuclear run-on assay, and changes in mRNA levels. We also identified direct Myc targets in human embryonic stem cells (ESCs). We further document that a Myc core signature (MCS) set of target genes is shared in mouse and human ESCs as well as in four other human cancer cell types. Remarkably, the expression of the MCS correlates with MYC expression in a cell-type independent manner across 8,129 microarray samples, which include 312 cell and tissue types. Furthermore, the expression of the MCS is elevated in vivo in Eμ-Myc transgenic murine lymphoma cells as compared with premalignant or normal B lymphocytes. Expression of the MCS in human B cell lymphomas, acute leukemia, lung cancers or Ewing sarcomas has the highest correlation with MYC expression. Annotation of this gene signature reveals Myc's primordial function in RNA processing, ribosome biogenesis and biomass accumulation as its key roles in cancer and stem cells

Pseudomonas aeruginosa H3-T6SS Combats H2O2 Stress by Diminishing the Amount of Intracellular Unincorporated Iron in a Dps-Dependent Manner and Inhibiting the Synthesis of PQS

The type VI secretion system (T6SS), a protein translocation nanomachine, is widely distributed in Gram-negative bacteria and delivers effectors directly into target cells or the extracellular environment to help the bacteria gain a competitive fitness advantage and promote bacterial survival in harmful environments. In this study, we demonstrated that the synthesis of the Pseudomonas quinolone signal (PQS) in Pseudomonas aeruginosa PAO1 was inhibited by the H3-T6SS gene cluster under iron-rich conditions, and that this inhibition was relieved under iron starvation conditions. Conversely, PQS differentially regulated the expression of the H3-T6SS structural genes and the effector protein gene tseF. The expression of tseF was inhibited by PQS, while the expressions of the H3-T6SS structural genes were positively regulated by PQS. Further studies showed that the H3-T6SS was involved in the resistance of P. aeruginosa to oxidative stress caused by hydrogen peroxide (H2O2). Interestingly, H3-T6SS expression was neither induced by H2O2 stress nor regulated by OxyR (a global anti-oxidative transcriptional regulator) but was positively regulated by RpoS (a major transcription regulator of the stress response). In addition, we found that the clpV3 (a structural gene of H3-T6SS) mutation resulted in upregulation of two proteins related to PQS synthesis and many proteins related to oxidative stress resistance, while the expression of some iron storage proteins, especially Dps, were significantly downregulated. Furthermore, the clpV3 mutation led to an increase in the intracellular free Fe2+ content of P. aeruginosa. Further studies showed that both the PQS deficient mutation and overexpression of dps effectively restored the H2O2 sensitive phenotype of the H3-T6SS mutant. Finally, we proposed the following model of H3-T6SS-mediated resistance to H2O2 stress in P. aeruginosa. H3-T6SS not only reduces the intracellular free Fe2+ level by upregulating the expression of ferritin Dps, but also inhibits the synthesis of PQS to mediate the resistance of P. aeruginosa to H2O2 stress. This study highlights the important role of H3-T6SS in the ability of P. aeruginosa to combat H2O2 stress and provides a perspective for understanding the stress response mechanism of bacteria