Aspergillus fumigatus conidial surface-associated proteome reveals factors for fungal evasion and host immunity modulation.

Aspergillus fumigatus causes aspergillosis and relies on asexual spores (conidia) for initiating host infection. There is scarce information about A. fumigatus proteins involved in fungal evasion and host immunity modulation. Here we analysed the conidial surface proteome of A. fumigatus, two closely related non-pathogenic species, Aspergillus fischeri and Aspergillus oerlinghausenensis, as well as pathogenic Aspergillus lentulus, to identify such proteins. After identifying 62 proteins exclusively detected on the A. fumigatus conidial surface, we assessed null mutants for 42 genes encoding these proteins. Deletion of 33 of these genes altered susceptibility to macrophage, epithelial cells and cytokine production. Notably, a gene that encodes a putative glycosylasparaginase, modulating levels of the host proinflammatory cytokine IL-1ß, is important for infection in an immunocompetent murine model of fungal disease. These results suggest that A. fumigatus conidial surface proteins are important for evasion and modulation of the immune response at the onset of fungal infection.

Enhanced saccharification levels of corn starch using as a strategy a novel amylolytic complex (AmyHb) from the thermophilic fungus Humicola brevis var. thermoidea in association with commercial enzyme.

Amylases represent a versatile group of catalysts that are used for the saccharification of starch because they can hydrolyze the glycosidic bonds of starch molecules to release glucose, maltose, and short-chain oligosaccharides. The amylolytic complex of the thermophilic filamentous fungus Humicola brevis var. thermoidea (AmyHb) was produced, biochemically characterized, and compared with the commercial amylase Termamyl. In addition, the biotechnological application of AmyHb in starch saccharification was investigated. The highest production was achieved using a wheat bran medium at 50 °C for 5-6 days in solid-state fermentation (849.6 ± 18.2 U·g-1) without the addition of inducers. Optimum amylolytic activity occurred at pH 5.0 at 60 °C, and stability was maintained between pH 5.0 and 6.0, with thermal stability at 50-60 °C, especially in the presence of Ca2+. These results were superior to those found with Termamyl. Both enzymes were strongly inhibited by Hg2+, Cu2+, and Ag+; however, AmyHb displayed increased activity in the presence of Mn2+ and Na+. In addition, AmyHb showed greater tolerance to a wide range of ethanol concentrations. AmyHb appears to be a complex consisting of glucoamylase and α-amylase, based on its substrate specificity and TLC. The hydrolysis tests on cornstarch flour showed that the cocktail of AmyHb50% + Termamyl50% significantly increased the release of glucose and total reducing sugars (36.6%) when compared to the enzymes alone. AmyHb exhibited promising physicochemical properties and good performance with commercial amylase; therefore, this complex is a biotechnological alternative candidate for the bioprocessing of starch sources.

Biochemical characterization, stability, and kinetics of three substrates of the recombinant TMPRSS2 serine protease domain.

Transmembrane serine protease 2 (TMPRSS2) is a membrane-bound protease belonging to the type II transmembrane serine protease (TTSP) family. It is a multidomain protein, including a serine protease domain responsible for its self-activation. The protein has been implicated as an oncogenic transcription factor and for its ability to cleave (prime) the SARS-CoV-2 spike protein. In order to characterize the TMPRSS2 biochemical properties, we expressed the serine protease domain (rTMPRSS2_SP) in Komagataella phaffii using the pPICZαA vector and purified it using immobilized metal affinity (Ni Sepharose™ excel) and size exclusion (Superdex 75) chromatography. We explored operational fluorescence resonance energy transfer FRET peptides as substrates. We chose the peptide Abz-QARK-(Dnp)-NH2 (Abz = ortho-aminobenzoic acid, the fluorescence donor, and Dnp = 2,4-dinitrophenyl, the quencher group) as a substrate to find the optimal conditions for maximum enzymatic activity. We found that metallic ions such as Ca2+ and Na+ increased enzymatic activity, but ionic surfactants and reducing agents decreased catalytic capacity. Finally, we determined the rTMPRSS2_SP stability for long-term storage. Altogether, our results represent the first comprehensive characterization of TMPRSS2's biochemical properties, providing valuable insights into its serine protease domain.

Genomic features and comparative analysis of a multidrug-resistant Acinetobacter bereziniae strain infecting an animal: a novel emerging one health pathogen?

Acinetobacter bereziniae has recently gained medical notoriety due to its emergence as a multidrug resistance and healthcare-associated pathogen. In this study, we report the whole-genome characterization of an A. bereziniae strain (A321) recovered from an infected semiaquatic turtle, as well as a comparative analysis of A. bereziniae strains circulating at the human-animal-environment interface. Strain A321 displayed a multidrug resistance profile to medically important antimicrobials, which was supported by a wide resistome. The novel Tn5393m transposon and a qnrB19-bearing ColE1-like plasmid were identified in A321 strain. Novel OXA-229-like ß-lactamases were detected and expression of OXA-931 demonstrated a 2-64-fold increase in the minimum inhibitory concentration for ß-lactam agents. Comparative genomic analysis revealed that most A. bereziniae strains did not carry any antimicrobial resistance genes (ARGs); however, some strains from China, Brazil, and India harbored six or more ARGs. Furthermore, A. bereziniae strains harbored conserved virulence genes. These results add valuable information regarding the spread of ARGs and mobile genetic elements that could be shared not only between A. bereziniae but also by other bacteria of clinical interest. This study also demonstrates that A. bereziniae can spill over from anthropogenic sources into natural environments and subsequently be transmitted to non-human hosts, making this a potential One Health bacteria that require close surveillance.

A phylogenetic approach to explore the Aspergillus fumigatus conidial surface-associated proteome and its role in pathogenesis.

Aspergillus fumigatus , an important pulmonary fungal pathogen causing several diseases collectively called aspergillosis, relies on asexual spores or conidia for initiating host infection. Here, we used a phylogenomic approach to compare proteins in the conidial surface of A. fumigatus , two closely related non-pathogenic species, Aspergillus fischeri and Aspergillus oerlinghausenensis , and the cryptic pathogen Aspergillus lentulus . After identifying 62 proteins uniquely expressed on the A. fumigatus conidial surface, we deleted 42 genes encoding conidial proteins. We found deletion of 33 of these genes altered susceptibility to macrophage killing, penetration and damage to epithelial cells, and cytokine production. Notably, a gene that encodes glycosylasparaginase, which modulates levels of the host pro-inflammatory cytokine IL-1ß, is important for infection in an immunocompetent murine model of fungal disease. These results suggest that A. fumigatus conidial surface proteins and effectors are important for evasion and modulation of the immune response at the onset of fungal infection.

Mutanase from Trichoderma harzianum inductively Produced by Mutan: Short-Term Treatment to Degrade Mature Streptococcus mutans Biofilm.

This study aimed to evaluate the disruptive effect of fungal mutanase against cariogenic biofilm after short-term treatment. For that, mature Streptococcus mutans biofilms (n = 9) were exposed to active or inactivated enzymes produced by Trichoderma harzianum for 1 min, two times per day. Biofilms were analyzed by amount of matrix water-insoluble polysaccharides, bacterial viability, acidogenicity, and morphology by scanning electron microscopy (SEM). The group treated with active enzymes (AE) had a significantly lower amount of insoluble polysaccharides (893.30 ± 293.69) when compared to the negative control group (NaCl, 2192.59 ± 361.96), yet no significant difference was found when comparing to the positive control group (CHX, 436.82 ± 151.07). Also, there was no significant effect on bacteria metabolism and viability (P-value < 0.05). Data generated by the quantitative analysis were confirmed through scanning electron microscopy images. Thus, fungal mutanase degraded the biofilm after a short-term treatment without interfering with bacterial viability and metabolism. Such findings offer insight to the development of routine oral care products containing this input.

Citrobacter meridianamericanus sp. nov., isolated from a soil sample.

A Gram-stain-negative strain, designated BR102T, isolated from a soil sample in Brazil was characterized by a polyphasic approach. Comparative 16S rRNA gene sequences indicated that strain BR102T belonged to the genus Citrobacter. The recN- and whole-genome-based phylogeny, and multilocus sequence analysis based on concatenated partial fusA, leuS, pyrG and rpoB sequences strongly supported a clade encompassing strain BR102T and a strain from public database that was distinct from currently recognized species of the genus Citrobacter. Average nucleotide identity and digital DNA-DNA hybridization values between strain BR102T and the closest relative Citrobacter freundii ATCC 8090T were 91.8 and 48.8 %, respectively. The ability to metabolize different compounds further discriminated strain BR102T from other closely related species of the genus Citrobacter. The novel variants bla CMY-179 and qnrB97, which encoded a CMY-2-like ß-lactamase and a QnrB-type protein, respectively, were identified in strain BR102T. BR102T was resistant to ampicillin, amoxicillin/clavulanate and cefoxitin. The DNA G+C content of strain BR102T is 51.3 mol%. Based on these results, strain BR102T represents a novel species of the genus Citrobacter, for which the name Citrobacter meridianamericanus sp. nov. is proposed. The type strain is BR102T (=MUM 22.55T=IMI 507229T).

Biochemical and biophysical properties of a recombinant serine peptidase from Purpureocillium lilacinum.

The industrial uses of peptidases have already been consolidated; however, their range of applications is increasing. Thus, the biochemical characterization of new peptidases could increase the range of their biotechnological applications. In silico analysis identified a gene encoding a putative serine peptidase from Purpureocillium lilacinum (Pl_SerPep), annotated as a cuticle-degrading enzyme. The Pl_SerPep gene product was expressed as a recombinant in a Komagataella phaffii (previously Pichia pastoris) expression system. The enzyme (rPl_SerPep) showed optimal pH and temperature of 8.0 and 60 °C, respectively. Moreover, rPl_SerPep has a higher thermal stability than the cuticle-degrading enzymes described elsewhere. The structural analysis indicated a conformational change in the rPl_SerPep secondary structure, which would allow an increase in catalytic activity at 60 °C. Komagataella phaffii secretes rPl_SerPep with the pro peptide in its inactive form. Low-resolution small-angle X-ray scattering (SAXS) analysis showed little mobility of the pro peptide portion, which indicates the apparent stability of the inactive form of the enzyme. The presence of 20 mM guanidine in the reaction resulted in the maintenance of activity, which was apparently a consequence of pro peptide structure flexibilization.

Isolation and characterization of the first phosphodiesterase (Bj-PDE) from the venom of Bothrops jararacussu snake.

Phosphodiesterases are exonucleases that sequentially hydrolyse phosphodiester bonds of polynucleotides from the 3'-end and release 5-mononucleotides. After more than one decade without any advance in the study of Bothropic phosphodiesterases, we described here the isolation of the first phosphodiesterase from Bothrops jararacussu, which we named Bj-PDE. A five-step column chromatography procedure (size exclusion, hydrophobic interaction, cation exchange, lentil lectin affinity, and blue sepharose affinity) enabled isolation of Bj-PDE with preserved and stable enzymatic activity (bis(p-nitrophenyl) phosphate substrate), Km = 6.9 mM (± 0.7 mM), kcat/Km = 1.7 × 104 M-1 s-1 (± 0.2 × 104 M-1 s-1), MW = 116 kDa (SDS-PAGE), optimum activity around 45 °C at pH 8.0, and stability for 81 days at different storage temperatures (8, -20, and - 80 °C). Ca2+ and Mg2+ ions positively influenced Bj-PDE activity, while EDTA had the opposite action. Zn2+ restored >50 % of enzyme activity after its inhibition by EDTA. The Bj-PDE partial sequence identified by mass spectrometry was very similar to the sequence of BATXPDE1 from Bothrops atrox, which was evolutionarily close to this new PDE. Therefore, our study represents an important progress on the isolation of this minor toxin and sheds new lights on the properties and bioprospection of bothropic phosphodiesterases.

Mango peel as a potential enzyme inducer in Trichoderma harzianum: a strategy for cariogenic biofilm degradation and reuse of industrial waste

Water-insoluble exopolysaccharides (I-EPS) are a virulence factor for dental biofilms. It has already been demonstrated that mango pulp induces the secretion of glucan-hydrolytic enzymes in the fungus Trichoderma harzianum, and that they have an effect on I-EPS from young biofilms. Aim: Evaluate the effect of mango peel as an enzyme inducer in T. harzianum, and the effect of enzymes secreted on mature biofilms. Methods: Fractions of the peel (PL) and ethanol-precipitated pulp (PP) of Tommy Atkins mangoes were sterilized and added to a culture medium containing T. harzianum for induction of hydrolytic enzymes. After 192 h, the culture medium was centrifuged and the supernatant (enzyme extract) was used as treatment on S. mutans biofilms (n=9): a) NaCl 0.9 %; b) 0.12 % chlorhexidine digluconate; and c) extract of enzymes induced by PL or PP. Acidogenicity, bacterial viability, quantification of insoluble polysaccharides, and three-dimensional analysis of the biofilm by scanning electron microscopy (SEM) was performed. Data were analyzed by ANOVA followed by the Tukey test (α=5 %). Results: The hydrolytic enzymes did not alter the metabolism or bacterial viability of the biofilm (p<0.05). Although the images obtained by SEM suggest some degree of matrix degradation, the quantification of I-EPS for the PL and PP groups did not differ from the control group (p>0.05), suggesting a slight effect on the disorganization of the mature S. mutans biofilm. Conclusion: The results suggest that mango peel fraction can induce secretion of mutanase by T. harzianum, however in an insufficient amount to generate significant degradation on cariogenic biofilm.

The Influence of Natural Barriers on the Amphidromous Shrimp Potimirim brasiliana (Caridea, Atyidae) from Two Rivers in Southeastern Brazil.

AbstractThe migratory behavior of freshwater shrimps may be affected by natural barriers in limnetic environments. This study evaluated the river areas separated by natural barriers, such as waterfalls, which affect the amphidromous shrimps' (Potimirim brasiliana) population features and reproductive aspects. Results indicate that in the Félix and Prumirim Rivers from southeastern Brazil shrimps show few differences in sampling areas, and these differences may not be causally related to the waterfalls. This is demonstrated by the absence of a pattern in the size and sex ratio in each area and the absence of a significant difference in most reproductive aspects. The presence of juveniles and reproductive individuals in all sampling areas strongly indicates a constant migration along them in both rivers, indicating that all individuals evaluated correspond to one single patchy population structure for each river. This migration conducted by P. brasiliana, such as its crawling behavior, demonstrated that it would be important to maintain the minimum number of individuals flowing between the different river sampling areas in this shrimp group. Thus, based on a helpful model observed in P. brasiliana, the results help us understand how natural barriers may affect the populations of amphidromous shrimp and how the migration behavior up- and downstream can help sustain the population. This premise can help future construction decisions and impacts of unnatural barriers, such as dams.

Enzyme engineering and its industrial applications.

Recently, there has been an increase in the demand for enzymes with modified activity, specificity, and stability. Enzyme engineering is an important tool to meet the demand for enzymes adjusted to different industrial processes. Knowledge of the structure and function of enzymes guides the choice of the best strategy for engineering enzymes. Each enzyme engineering strategy, such as rational design, directed evolution, and semi-rational design, has specific applications, as well as limitations, which must be considered when choosing a suitable strategy. Engineered enzymes can be optimized for different industrial applications by choosing the appropriate strategy. This review features engineered enzymes that have been applied in food, animal feed, pharmaceuticals, medical applications, bioremediation, biofuels, and detergents.

Transcriptomic studies on Purpureocillium lilacinum reveal molecular mechanisms of response to fluconazole and itraconazole.

Filamentous fungus Purpureocillium lilacinum is an emerging pathogen that infects immunocompromised and immunocompetent individuals and is resistant to several azole molecules. Although azole resistance mechanisms are well studied in Aspergillus sp. and Candida sp., there are no studies to date reporting P. lilacinum molecular response to these molecules. The aim of this study was to describe P. lilacinum molecular mechanisms involved in antifungal response against fluconazole and itraconazole. Transcriptomic analyses showed that gene expression modulation takes place when P. lilacinum is challenged for 12 h with fluconazole (64 µg/mL) or itraconazole (16 µg/mL). The antifungals acted on the ergosterol biosynthesis pathway, and two homologous genes coding for cytochrome P450 51 enzymes were upregulated. Genes coding for efflux pumps, such as the major facilitator superfamily transporter, also displayed increased expression in the treated samples. We propose that P. lilacinum develops antifungal responses by raising the expression levels of cytochrome P450 enzymes and efflux pumps. Such modulation could confer P. lilacinum high levels of target enzymes and could lead to the constant withdrawal of antifungals, which would force an increase in the administration of antifungal medications to achieve fungal morbidity or mortality. The findings in this work could aid in the decision-making for treatment strategies in cases of P. lilacinum infection.

Peptides: Molecular and Biotechnological Aspects.

Since the isolation and commercialization of insulin (a peptide composed of 51 amino acid residues) in the early 1920s, peptide drugs have reshaped the pharmaceutical industry [...].

Ethanol from rice byproduct using amylases secreted by Rhizopus microsporus var. oligosporus. Enzyme partial purification and characterization.

A three-stage bioethanol bioprocess was developed. Firstly, amylases were obtained from Rhizopus microsporus var. oligosporus using wheat bran in solid-state fermentation. Secondly, amylases hydrolyzed a rice byproduct to make a glucose-rich solution, and this sugar was finally metabolized by Saccharomyces cerevisiae to produce bioethanol. Besides, the secreted enzymes were also partially purified and characterized. The amylase activity (AA) in the crude extract was 358 U/g substrate, and the partially purified enzyme showed the best activity in the 4.0-5.5 pH range. A wide pH stability range (3.5-8.5) was confirmed. The amylase was thermostable up to 60 °C. The ion Mn+2 (10 mM) improved by 60% the AA. There was a 54.9% yield in the conversion of rice residues into reducing sugars in 10 h. The glucose-rich solution was undergone fermentation by S. cerevisiae and showed high ethanol efficiency, 95.8% of the theoretical value. These results suggested a promising technology for bioethanol production.

Evaluation of the milk clotting properties of an aspartic peptidase secreted by Rhizopus microsporus.

Traditionally, chymosin has been used for milk-clotting, but this naturally occurring enzyme is in short supply and its use has raised religious and ethical concerns. Because milk-clotting peptidases are a promising substitute for chymosin in cheese preparation, there is a need to find and test the specificity of these enzymes. Here, we evaluated the milk-clotting properties of an aspartic peptidase secreted by Rhizopus microsporus. The molecular mass of this enzyme was estimated at 36 kDa and Pepstatin A was determined to be an inhibitor. Optimal activity occurred at a pH of 5.5 and a temperature range of 50-60 °C, but the peptidase was stable in the pH range of 4-7 and a temperature as low as 45 °C. Proteolytic activity was significantly reduced in the presence of Cu2+ and Al3+. When enzyme substrates based on FRET were used, this peptidase exhibited the highest catalytic efficiency for Abz-KNRSSKQ-EDDnp (4,644 ± 155 mM-1.s-1), Abz-KLRSSNQ-EDDnp (3,514 ± 130 mM-1.s-1), and Abz-KLRQSKQ-EDDnp (3,068 ± 386 mM-1.s-1). This study presents a promising peptidase for use in cheese making, due to its high stability in the presence of Ca2+ and broad pH range of 4-7, in addition to its ability to efficiently clot milk.

Amino Acid Supplementation Improves the Production of Extracellular Peptidases by Aspergillus Section Flavi and their Ionic Immobilization

Abstract Bioprocess studies have been highlighted due to the importance of physiological processes and industrial applications of enzymes. The potential of peptidase production from Aspergillus section Flavi using different amino acids as a supplemental nitrogen source was investigated. A production profile revealed that amino acids had positive effects on peptidase production when compared to the control without amino acids. Optimal production (100 U/mL) was obtained with Arginine amino acid in 96 h of fermentation. Extracellular peptidase from Aspergillus section Flavi was identified in submerged bioprocesses by in situ activity. Biochemical studies revealed that the maximum activities of the enzyme extract were obtained at pH 6.5 and a temperature of 55°C. The inhibition by EDTA and PMSF suggests the presence of more than one peptidase while the Ni2+ and Cu2+ had a negative influence on the enzyme activity. When the crude extract was reversibly immobilized on ionic supports, DEAE-Agarose and MANAE-Agarose the derivative showed different profiles of thermal and pH stabilities. Hence, this study revealed the basic properties and biochemical characteristics that allowed the production improvement of this class of enzyme. Moreover, with known properties stabilization and immobilization process is required to further explore its biotechnological capacities.

Chemosensitizing Effect of Cernumidine Extracted from Solanum cernuum on Bladder Cancer Cells in Vitro.

Cernumidine (CER) is a guanidinic alkaloid isolated from Solanum cernuum leaves. In this work, we investigated the cytotoxicity, chemosensitizing effect of cernumidine to cisplatin (cDDP) and the possible mechanism of action of the combination on bladder cancer cells. Cernumidine showed cytotoxicity and could sensitize bladder cancer cells to cisplatin. The combination of CER+cDDP inhibited cell migration on T24 cells. CER+cDDP down-regulated MMP-2/9 and p-ERK1/2, while it increased EGFR activity corroborating the observed cell migration inhibition. Down-regulation of Bcl-2 and up-regulation pro-apoptotic Bax and further depletion of the mitochondrial membrane potential (ΔΨm) indicates that mitochondria play a central role in the combination treatment inducing the mitochondrial signaling pathway of apoptosis in T24 cells. Our data showed that the alkaloid cernumidine is worthy of further studies as a chemosensitizing agent to be used in complementary chemotherapy.

Subproteome of Lachesis muta rhombeata venom and preliminary studies on LmrSP-4, a novel snake venom serine proteinase.

BACKGROUND: Lachesis muta rhombeata is one of the venomous snakes of medical importance in Brazil whose envenoming is characterized by local and systemic effects which may produce even shock and death. Its venom is mainly comprised of serine and metalloproteinases, phospholipases A2 and bradykinin-potentiating peptides. Based on a previously reported fractionation of L. m. rhombeata venom (LmrV), we decided to perform a subproteome analysis of its major fraction and investigated a novel component present in this venom. METHODS: LmrV was fractionated through molecular exclusion chromatography and the main fraction (S5) was submitted to fibrinogenolytic activity assay and fractionated by reversed-phase chromatography. The N-terminal sequences of the subfractions eluted from reversed-phase chromatography were determined by automated Edman degradation. Enzyme activity of LmrSP-4 was evaluated upon chromogenic substrates for thrombin (S-2238), plasma kallikrein (S-2302), plasmin and streptokinase-activated plasminogen (S-2251) and Factor Xa (S-2222) and upon fibrinogen. All assays were carried out in the presence or absence of possible inhibitors. The fluorescence resonance energy transfer substrate Abz-KLRSSKQ-EDDnp was used to determine the optimal conditions for LmrSP-4 activity. Molecular mass of LmrSP-4 was determined by MALDI-TOF and digested peptides after trypsin and Glu-C treatments were analyzed by high resolution MS/MS using different fragmentation modes. RESULTS: Fraction S5 showed strong proteolytic activity upon fibrinogen. Its fractionation by reversed-phase chromatography gave rise to 6 main fractions (S5C1-S5C6). S5C1-S5C5 fractions correspond to serine proteinases whereas S5C6 represents a C-type lectin. S5C4 (named LmrSP-4) had its N-terminal determined by Edman degradation up to the 53rd amino acid residue and was chosen for characterization studies. LmrSP-4 is a fibrinogenolytic serine proteinase with high activity against S-2302, being inhibited by PMSF and benzamidine, but not by 1,10-phenantroline. In addition, this enzyme exhibited maximum activity within the pH range from neutral to basic and between 40 and 50 °C. About 68% of the LmrSP-4 primary structure was covered, and its molecular mass is 28,190 Da. CONCLUSIONS: Novel serine proteinase isoforms and a lectin were identified in LmrV. Additionally, a kallikrein-like serine proteinase that might be useful as molecular tool for investigating bradykinin-involving process was isolated and partially characterized.