A novel fibrin(ogen)olytic trypsin-like protease from Chinese oak silkworm (Antheraea pernyi): Purification and characterization

Biomolecular characterization of Antheraea mylitta cocoonase: A secreted protease

Cocoonase is a protease secreted during the emergence of silk moths. In the present study cocoonase of Antheraea mylitta was collected, purified and secondary structure was determined using circular dichroism (CD) spectroscopy which revealed the presence of α-helix 4.3%, β-sheet 55%, turn 8% and random coil 32.7%. The thermal stability of cocoonase was studied using CD spectroscopy while the thermal property was observed using Differential Scanning Calorimetry (DSC). Furthermore, MALDI-TOF peptide mass fingerprinting (PMF) was performed for similar protein identification using the MASCOT server. Using casein as the substrate, the kinetic constants Km and Vmax were 13 × 103 mg/ml and 15.09 × 10-2 μg/mg.s1 respectively. The specific activity of cocoonase was observed to be maximum at temperature 40 °C, pH-8.0. The effect of heavy metals Hg2+, Cd2+, Co2+, Pb2+ showed inhibitory activity at higher concentrations, while few metals like Mn2+, Fe3+ enhanced the activity while the effect of Ca2+ was not much on the activity. Soybean trypsin inhibitor and PMSF showed an inhibitory effect on the activity of cocoonase. Additionally, antioxidant scavenging and fibrinolytic properties were also observed. Furthermore, the imperative information generated through the present study will serve to explore cocoonase for its prospective pharmaceutical applications.

Evaluating the role of trypsin in silk degumming: An in silico approach

The trypsin being universal enzyme forming family of proteases catalyzes the hydrolysis of proteins into amino acids and regenerates the serine hydroxyl an active site. The trypsin enzyme from D. saccharalis, uses sericin as its preferred substrate. Presence of catalytic triad (serine, aspartic acid and histidine) at the substrate binding site of this enzyme is very important for the catalytic activity. In the current study, the interacting mechanism between the substrate sericin protein and enzyme trypsin protein were explored by integrating various computational approaches including physico-chemical properties, biophysical properties, dynamics, gene ontology, molecular docking, protein - protein interactions, binding free energy calculation and structural motifs were studied. The evolutionary study performed by MEGA X showed that trypsin protein sequence (ALE15212.1) is closely related to cocoonase protein sequence (ADG26770.1) from Antheraea pernyi. 3-D models of trypsin and sericin proteins were predicted using I-TASSER and further validated by PROCHECK, and ProSAweb softwares. The predicted trypsin structure model was assigned E.C. no. 3.4.21.4 which refers hydrolytic mechanism. Gene Ontology predicted by QuickGO showed that trypsin has serine hydrolase activity (GO: 00017171), and part of proteolysis (GO: 0006508) as well as protein metabolic process (GO:0019538) actvity. Molecular docking studies between trypsin and sericin proteins were conducted by the HADDOCK 2.4 having best docked protein complex with Z-score - 1.9. 2D and 3D protein-protein interaction was performed with LIGPLOT⁺ and HAWKDOCK, PDBsum, respectively. The amino acid residues interacting across proteins interface are sericin_chain A representing "Ser133, Tyr214, Thr188, Thr243, Ser225, Ser151, Ser156, His294, Arg293, Gly296″ and trypsin_chain B "Lys120, Tyr246, Asn119, Glu239, Ser62, Tyr194, Ile197, Ser171, Tyr169, Gly170″. Based on our results trypsin shows similarity with cocoonase and presumably trypsin can be used as an alternative source in cocoon degumming.

In silico structural and functional characterization of Antheraea mylitta cocoonase

Background

Cocoonase is a serine protease present in sericigenous insects and majorly involved in dissolving of sericin protein allowing moth to escape. Cocoon structure is made up of sericin protein which holds fibroin filaments together. Cocoonase enzyme hydrolyzes sericin protein without harming the fibroin. However, until date, no detailed characterization of cocoonase enzyme and its presence in wild silk moth Antheraea mylitta has been carried out. Therefore, current study aimed for detailed characterization of amplified cocoonase enzyme, secondary and tertiary structure prediction, sequence and structural alignment, phylogenetic analysis, and computational validation. Several computational tools such as ProtParam, Iterative Threading Assembly Refinement (I-TASSER), PROCHECK, SAVES v6.0, TM-align, Molecular Evolutionary Genetics Analysis (MEGA) X, and Figtree were employed for characterization of cocoonase protein.

Results

The present study elucidates about the isolation of RNA, cDNA preparation, PCR amplification, and in silico characterization of cocoonase from Antheraea mylitta. Here, total RNA was isolated from head region of A. mylitta, and gene-specific primers were designed using Primer3 followed by PCR-based amplification and sequencing. The newly constructed 377-bp length sequence of cocoonase was subjected to in silico characterization. In silico study of A. mylitta cocoonase showed 26% similarity to A. pernyi strain Qing-6 cocoonase using Blastp and belongs to member of chymotrypsin-like serine protease superfamily. From phylogenetic study, it was found that A. mylitta cocoonase sequence is closely related to A. pernyi cocoonase sequence.

Conclusions

The present study revealed about the detailed in silico characterization of cocoonase gene and encoded protein obtained from A. mylitta head region. The results obtained infer the presence of cocoonase enzyme in the wild silkworm A. mylitta and can be used for cocoon degumming which will be a valuable and cost-effective strategy in silk industry.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00367-8.

Unraveling the distinctive venomous features of the saturniid Hylesia sp.: An integrative approach of a public health concern in Argentina

The saturniid genus Hylesia is well known for the cutaneous lepidopterism induced by airborne setae on contact with the skin. Although several cases of such dermatitis have been reported in Argentina, no information about their venoms and toxicological implications on human health is available yet. Thus, we conducted a morphological analysis of the setae/spines and a toxinological characterization (through biological assays and proteomic techniques) of the bristle extract from caterpillars and moths of Hylesia sp. from Misiones, Argentina. By scanning electron microscopy, we revealed the various and distinctive types of urticating structures: harpoon-shaped or spiny setae in caterpillars, and setae with barb-like structures in female moths. Their venom electrophoretic profiles were substantially different, presenting proteins related to toxicity, such as serpins and serine peptidases. The female moth venom exhibited higher caseinolytic activity than the caterpillar venom, and coincidentally only the former noticeably hydrolyzed fibrinogen and gelatin. In addition, the female venom displayed a dose-dependent procoagulant effect. The injection of this venom into mouse skin led to the rapid detection of an increased number of intact and degranulated mast cells in the dermis; a few areas of focal subcutaneous hemorrhage were also observed after 5 h of injection. Altogether, this study provides relevant information about the pathophysiological mechanisms whereby Hylesia sp. from northeastern Argentina can induce toxicity on human beings, and paves the way for treatment strategies of accidents caused by this saturniid lepidopteran.

Cocoonase is indispensable for Lepidoptera insects breaking the sealed cocoon

Many insects spin cocoons to protect the pupae from unfavorable environments and predators. After emerging from the pupa, the moths must escape from the sealed cocoons. Previous works identified cocoonase as the active enzyme loosening the cocoon to form an escape-hatch. Here, using bioinformatics tools, we show that cocoonase is specific to Lepidoptera and that it probably existed before the occurrence of lepidopteran insects spinning cocoons. Despite differences in cocooning behavior, we further show that cocoonase evolved by purification selection in Lepidoptera and that the selection is more intense in lepidopteran insects spinning sealed cocoons. Experimentally, we applied gene editing techniques to the silkworm Bombyx mori, which spins a dense and sealed cocoon, as a model of lepidopteran insects spinning sealed cocoons. We knocked out cocoonase using the CRISPR/Cas9 system. The adults of homozygous knock-out mutants were completely formed and viable but stayed trapped and died naturally in the cocoon. This is the first experimental and phenotypic evidence that cocoonase is the determining factor for breaking the cocoon. This work led to a novel silkworm strain yielding permanently intact cocoons and provides a new strategy for controlling the pests that form cocoons.

Spinning and cocooning are the instincts of many insects, providing a shelter to the residing pupae to resist adverse factors. After the metamorphosis of pupa into adult, the adult must break open the cocoon to emerge, which is called decocooning. We have bioinformatically identified that cocoonase is specific to Lepidoptera, and demonstrated that it is the determining factor for breaking the sealed cocoon experimentally for the first time. This work led to a novel silkworm strain yielding permanently intact cocoons and provides a new strategy for controlling the pests that form cocoons and for breeding.

Computational modeling of culture media for enhanced production of fibrinolytic enzyme from marine bacterium Fictibacillus sp. strain SKA27 and in vitro evaluation of fibrinolytic activity

The present study reports the optimized production and purification of an extremely active fibrinolytic enzyme from newly isolated marine bacterium Fictibacillus sp. strain SKA27, with a specific activity of 125,107.85 U/mg and an apparent molecular weight of 28 kDa on SDS-PAGE. Wheat bran extract used for submerged production proved to be highly beneficial and enhanced fibrinolytic enzyme production when combined with yeast extract and CaCl₂. Optimization of culture media by response surface methodology (RSM) resulted in high root mean square error (RMSE), which led to the training of a back propagation multilayer artificial neural network (ANN) with 3-5-1 topology for better prediction quality. The prediction and optimization capabilities of regression and ANN were critically examined and ANN displayed higher proficiency with R ² of 0.99 and RMSE of 2.0 compared to 0.98 R ² and 48.9 RMSE of the regression model. An adept ANN linked genetic algorithm (GA) optimized the medium components to achieve 1.8-fold higher enzyme production (4175.41 U/mL). Further, a new and improved in vitro qualitative analysis displayed high specificity of purified enzyme to fibrin.

Evolutionary and structural analyses uncover a role for solvent interactions in the diversification of cocoonases in butterflies

Multi-omic approaches promise to supply the power to detect genes underlying disease and fitness-related phenotypes. Optimal use of the resulting profusion of data requires detailed investigation of individual candidate genes, a challenging proposition. Here, we combine transcriptomic and genomic data with molecular modelling of candidate enzymes to characterize the evolutionary history and function of the serine protease cocoonase. Heliconius butterflies possess the unique ability to feed on pollen; recent work has identified cocoonase as a candidate gene in pollen digestion. Cocoonase was first described in moths, where it aids in eclosure from the cocoon and is present as a single copy gene. In heliconiine butterflies it is duplicated and highly expressed in the mouthparts of adults. At least six copies of cocoonase are present in Heliconius melpomene and copy number varies across H. melpomene sub-populations. Most cocoonase genes are under purifying selection, however branch-site analyses suggest cocoonase 3 genes may have evolved under episodic diversifying selection. Molecular modelling of cocoonase proteins and examination of their predicted structures revealed that the active site region of each type has a similar structure to trypsin, with the same predicted substrate specificity across types. Variation among heliconiine cocoonases instead lies in the outward-facing residues involved in solvent interaction. Thus, the neofunctionalization of cocoonase duplicates appears to have resulted from the need for these serine proteases to operate in diverse biochemical environments. We suggest that cocoonase may have played a buffering role in feeding during the diversification of Heliconius across the neotropics by enabling these butterflies to digest protein from a range of biochemical milieux.

Fibrinogen and fibrin are novel substrates for Fasciola hepatica cathepsin L peptidases

Cathepsin peptidases form a major component of the secreted proteins of the blood-feeding trematodes Fasciola hepatica and Schistosoma mansoni. These peptidases fulfill many functions, from facilitating infection to feeding and immune evasion. In this study, we examined the Fasciola cathepsin L peptidases FhCL1, FhCL2, and FhCL3 and the schistosomal cathepsin peptidases SmCB1 and SmCL3 for their anticoagulant properties. Although no direct anticoagulant effect of these peptidases was observed, we discovered that cathepsin peptidases from Fasciola, but not from Schistosoma, were able to degrade purified fibrinogen, with FhCL1 having the highest fibrinogenolytic activity. Additionally, FhCL1 and FhCL2 both efficiently degraded fibrin. The lack of a direct anticoagulant or fibrinolytic effect of these peptidases is explained by their inhibition by plasma components. However, within the parasite gut, high concentrations of these peptidases could induce an anticoagulant environment, facilitating blood-feeding for extended periods.

Purification and characterization of a novel trypsin-like protease from green-seeded chickpea (Cicer arientum)

The present study describes the purification and physicochemical and biochemical characterization of trypsin-like protease from green-seeded chickpea (Cicer arientum). The crude extract of chickpea trypsin (CpT) was obtained by homogenization followed by differential ammonium sulfate precipitation. The CpT was purified by ion-exchange chromatography on diethylaminoethyl (DEAE) column, pre-equilibrated with 20 mM tris-CaCl₂ buffer (pH 8.2) with a flow rate of 0.5 mL min^-1. The molecular weight and purity of ∼23 kDa of CpT were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Activity of protease was determined using Nα-benzoyl-DL-arginine-p-nitroanilide as chromogenic substrate and CpT purified showed a specific inhibitor activity of 26978.7697 U mg^-1, fold purity of 9.8, and the yield of 70.2%. The characterization was performed for thermal stability, pH profile, and effect of various inhibitors on enzymatic activity. The protein isolated showed stability in the neutral to mild alkaline pH range and thermostability up to 50°C. CpT confirmed its serine nature as it was appreciably inhibited by serine protease inhibitors (maximum 6%), whereas metalloprotease inhibitors barely affected the activity of the enzyme (85%). To the best of our knowledge, it is first reported on purification of protease with trypsin-like properties, from this source.

Isolation and identification of a novel fibrinolytic Bacillus tequilensis CWD-67 from dumping soils enriched with poultry wastes

A newly isolated strain, CWD-67, which exhibited high fibrinolytic activity, was screened from dumping soils enriched with poultry wastes. The strain was identified as Bacillus tequilensis (KF897935) by 16Sr RNA gene sequence analysis and biochemical characterization. A fibrinolytic enzyme was purified to homogeneity from the culture supernatant using ammonium sulfate precipitation, membrane concentration, dialysis, ion-exchange, and gel filtration chromatography. SDS-PAGE analysis showed that the purified enzyme was a monomeric protein with an apparent molecular weight of 22 kDa, which is the lowest among Bacillus fibrinolytic enzymes reported to date. The purified enzyme was confirmed to have fibrinolytic activity by a fibrin zymogram. The optimal pH and temperature values of the enzyme were 8.0 and 45 °C, respectively. The enzyme was completely inhibited by PMSF and significantly inhibited by EDTA, TPCK, Co(2+), Zn(2+), and Cu(2+), suggesting a chymotrypsin-like serine metalloprotease. In vitro assays revealed that the purified enzyme could catalyze fibrin lysis effectively, indicating that this enzyme could be a useful fibrinolytic agent.

Purification and characterization of a novel fibrinolytic enzyme from Whitmania pigra Whitman

A fibrinolytic enzyme was purified from the dry body of Whitmania pigra Whitman. The fibrinolytic enzyme was purified to homogeneity with a yield of 0.003% and a purification of 630.7 fold. The molecular weight of the enzyme was estimated to be 26.7 kDa by reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme was tested by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and it showed that the enzyme was a novel fibrinolytic enzyme. The optimal pH and temperature of the enzyme were 8.5 and 55°C, respectively. Enzyme activity was enhanced by Na⁺, Mg^2+, and K⁺. On the contrary, the proteolytic activity was significantly inhibited by Mn²⁺, Fe²⁺, Fe³⁺, ethylenediaminetetraacetic acid (EDTA), and ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA). Fibrinolytic and fibrinogenolytic assays showed that the enzyme preferentially hydrolyzed fibrinogen Aα-chains, followed by Bβ- and γ-chains. The α-, β-, and γ-γ-chains of fibrin were also degraded by the enzyme.

Purification and biochemical characterization of a novel fibrinolytic enzyme, PSLTro01, from a medicinal animal Porcellio scaber Latreille

A novel protease, named PSLTro01, with fibrinolytic and anticoagulant activity was isolated from Porcellio scaber Latreille and was purified by a combination of hollow fibre membrane molecular weight cut-off (MWCO), ammonium sulfate fractionation, gel filtration and ion-exchange chromatography. PSLTro01 is a single-chain protein with a molecular mass of 38,497 Da as estimated by non-reduced SDS-PAGE and MALDI-TOF MS spectrometry, and its N-terminal 15 amino acid sequence was determined as DINGGGATLPQPLYQ. PSLTro01 is stable in the range of 20-40 °C and pH 6.0-10.0, with a maximum fibrinolytic activity at 40 °C and pH 7.0. The PSLTro01-induced fibrinolytic activity was not influenced by K(+) or Na(+) but was slightly increased by Mg(2+) and completely inhibited by aprotinin and pepstatin A. Fibrin plate assays revealed that PSLTro01 could not directly degrade fibrin but was a plasminogen activator. PSLTro01 exhibited high specificity for the substrate S-2251 for plasmin, followed by S-2238 for thrombin and S-2444 for urokinase. Moreover, the fibrinogenolysis pattern of PSLTro01 was Aα-chains>Bβ-chains>γ-chain. Tail-thrombus of the enzyme treated group was significantly shorter than the physiological saline treated group and the thrombus decrement was correlated with the enzyme dose. PSLTro01 prolongs both thrombin time (TT) and activated partial thromboplastin time (APTT). These results indicate that PSLTro01 may have potential applications in the prevention and treatment of thrombosis.

Antiplatelet and antithrombotic activity of a fibrin(ogen)olytic protease from Bacillus cereus strain FF01

Fibrin(ogen)olytic enzymes offer great promise for the treatment of thrombosis associated disorders. The present study describes the characterization of an extracellular fibrin(ogen)olytic serine protease (named Bacethrombase) purified from the Bacillus cereus strain FF01. The molecular mass of the Bacethrombase was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and matrix assisted laser desorption/ionization-time-of-flight-mass spectroscopy analyses at 39.5 kDa and 38,450.51 Da, respectively. The peptide mass fingerprinting and analyses of the composition of the amino acids revealed the similarity of the Bacethrombase to the bacterial serine proteases. The secondary structure of the Bacethrombase was composed of 14% helix, 6.6% beta-sheet, and 79.4% random coil. Bacethrombase was found to contain 48% sialic acid and it preferentially degraded the Aα-chain of fibrinogen, as well as fibrin. The anticoagulant potency of the Bacethrombase was comparable with that of warfarin and heparin, and was corroborated by its fibrinogenolytic activity rather than the inhibition of thrombin, prothrombin or FXa. Bacethrombase demonstrated antiplatelet activity, and dose-dependently inhibited the ADP-induced platelet aggregation. Bacethrombase (10 mg/kg) did not show toxicity after i.v. administration in Wistar rats; however, it revealed an in vivo anticoagulant effect and significantly inhibited the carrageenan-induced in vivo thrombus formation in rats.

An active recombinant cocoonase from the silkworm Bombyx mori: bleaching, degumming and sericin degrading activities

BACKGROUND

Cocoonase is a serine protease produced by silk moths and used for softening the cocoons so that they can escape. Degumming is one of the important steps in silk processing. This research aimed to produce an active recombinant Bombyx mori cocoonase (BmCoc) for the silk degumming process.

RESULTS

A recombinant BmCoc was successfully expressed in a Pichia pastoris system. The purified enzyme showed specific activity of 227 U mg(-1) protein, 2.4-fold purification, 95% yield and a molecular weight of 26 kDa. The enzyme exhibited optimal temperature at 40 °C and optimal pH at 8, and showed thermal stability at 25-45 °C and pH stability at 5-9. The recombinant enzyme exhibited sericin degumming ability and color bleaching characteristics, and did not affect the fibroin fiber. The enzyme also degraded sericin substrate with a product size about 30-70 kDa.

CONCLUSION

In this study, we successfully produced the active recombinant BmCoc in P. pastoris with promising functions for the Thai silk degumming process, which includes degumming, sericin degrading and color bleaching activities. Our data clearly indicated that the recombinant enzyme had proteolytic activity on sericin but not on fibroin proteins. The recombinant BmCoc has proven to be suitable for numerous applications in the silk industry.

In Vivo Anticoagulant and Thrombolytic Activities of a Fibrinolytic Serine Protease (Brevithrombolase) With the k-Carrageenan-Induced Rat Tail Thrombosis Model

In the present study, in vivo thrombolysis efficiency of Brevithrombolase, a nontoxic fibrinolytic enzyme purified from Brevibacillus brevis strain FF02B, was affirmed by significant inhibition of thrombus formation in the k-carrageenan-induced rat tail, in a dose-dependent manner. Brevithrombolase at a dose of 600 µg/kg showed an efficacy that was comparable to streptokinase and plasmin, in dissolving in vivo thrombus of k-carrageenan-treated rats under identical conditions. The in vivo anticoagulant property of Brevithrombolase was demonstrated by its prolongation of activated partial thromboplastin time, prothrombin time, and thrombin time in Wistar rats. However, the Brevithrombolase-treated rats demonstrated an insignificant decrease in fibrinogen (Fg) level of plasma compared with Fg level of control group of rats corroborating in vivo as well as in vitro anticoagulant activity of Brevithrombolase is due to its hydrolytic action on thrombin. These findings unequivocally suggest that Brevithrombolase may serve a promising alternative to the commercial thrombolytic drugs.