MDR49 coding for both P-glycoprotein and TMOF transporter functions in ivermectin resistance, trypsin activity inhibition, and fertility in the yellow fever mosquito, Aedes aegypti

This study investigated the function of the MDR49 gene in Aedes aegypti. MDR49 mutants were constructed using CRISPR/Cas9 technology; the mutation led to increased sensitivity to ivermectin (LC50: from 1.3090 mg L-1 to 0.5904 mg L-1), and a reduction in midgut trypsin activity. These findings suggest that the P-gp encoded by MDR49 confers resistance to ivermectin and impacts the reproductive function in Ae. aegypti. RNA interference technology showed that knockdown of MDR49 gene resulted in a significant decrease in the expression of VGA1 after a blood meal, as well as a decrease in the number of eggs laid and their hatching rate. LC-MS revealed that following ivermectin treatment, the MDR493d+2s/3d+2s strain larvae exhibited significantly higher drug concentrations in the head and fat body compared to the wild type. Modeling of inward-facing P-gp and molecular docking found almost no difference in the affinity of P-gp for ivermectin before and after the mutation. However, modeling of the outward-facing conformation demonstrated that the flexible linker loop between TM5 and TM6 of P-gp undergoes changes after the mutation, resulting in a decrease in trypsin activity and an increase in sensitivity to ivermectin. These results provide useful insights into ivermectin resistance and the other roles played by the MDR49 gene.

StMLP1, as a Kunitz trypsin inhibitor, enhances potato resistance and specifically expresses in vascular bundles during Ralstonia solanacearum infection

Miraculin-like proteins (MLPs), members of the Kunitz trypsin inhibitor (KTI) family that are present in various plants, have been discovered to have a role in defending plants against pathogens. In this study, we identified a gene StMLP1 in potato that belongs to the KTI family. We found that the expression of StMLP1 gradually increases during Ralstonia solanacearum (R. solanacearum) infection. We characterized the promoter of StMLP1 as an inducible promoter that can be triggered by R. solanacearum and as a tissue-specific promoter with specificity for vascular bundle expression. Our findings demonstrate that StMLP1 exhibits trypsin inhibitor activity, and that its signal peptide is essential for proper localization and function. Overexpression of StMLP1 in potato can enhance the resistance to R. solanacearum. Inhibiting the expression of StMLP1 during infection accelerated the infection by R. solanacearum to a certain extent. In addition, the RNA-seq results of the overexpression-StMLP1 lines indicated that StMLP1 was involved in potato immunity. All these findings in our study reveal that StMLP1 functions as a positive regulator that is induced and specifically expressed in vascular bundles in response to R. solanacearum infection.

Combination of three null mutations affecting seed protein accumulation in pea (Pisum sativum L.) impacts positively on digestibility

The presence of so-called anti-nutritional factors can reduce the bioavailability of nutrients following consumption of seeds which are otherwise an excellent source of proteins, carbohydrates and micronutrients. Among the proteins associated with negative effects on quality in pea (Pisum sativum L.) seeds are lectin, pea albumin 2 (PA2) and trypsin inhibitors (TI). Here we have investigated the impact of these proteins on protein digestibility and amino acid availability, using naturally occurring and derived mutant lines of pea lacking these proteins. The mutations were stacked to generate a triple mutant which was compared with a wild-type progenitor and a line lacking the major seed trypsin inhibitors alone. In vitro digestions following the INFOGEST protocol revealed significant differences in the degree of hydrolysis, protein profile and apparent amino acid availability among the pea variants. Proteins resistant to digestion were identified by MALDI-TOF mass spectrometry and amino acid profiles of digested samples determined. The results indicate that pea seeds lacking certain proteins can be used in the development of novel foods which have improved protein digestibility, and without negative impact on seed protein concentration or yield.

NaMLP, a new identified Kunitz trypsin inhibitor regulated synergistically by JA and ethylene, confers Spodoptera litura resistance in Nicotiana attenuata

We identified a miraculin-like protein (NaMLP) who is a new Kunitz trypsin inhibitor regulated synergistically by JA and ethylene signals and confers Spodoptera litura resistance in wild tobacco Nicotiana attenuata. The findings revealed a new source of trypsin inhibitor activities after herbivory, and provide new insights into the complexity of the regulation of trypsin inhibitor-based defense after insect herbivore attack. Upon insect herbivore attack, wild tobacco Nicotiana attenuata accumulates trypsin protease inhibitor (TPI) activities as a defense response from different protease inhibitor (PI) coding genes, including WRKY3-regulated NaKTI2, and JA-dependent NaPI. However, whether any other TPI gene exists in N. attenuata is still unclear. A miraculin-like protein gene (NaMLP) was highly up-regulated in N. attenuata after Alternaria alternata infection. However, silencing or overexpression of NaMLP had no effect on the lesion diameter developed on N. attenuata leaves after A. alternata inoculation. Meanwhile, the transcripts of NaMLP could be induced by wounding and amplified by Spodoptera litura oral secretions (OS). S. litura larvae gained significantly more biomass on NaMLP-silenced plants but less on NaMLP overexpressed plants. Although NaMLP showed low sequence similarity to NaKTI2, it had conserved reaction sites of Kunitz trypsin inhibitors, and exhibited TPI activities when its coding gene was overexpressed transiently or stably in N. attenuata. This was consistent with the worst performance of S. litura larvae on NaMLP overexpressed lines. Furthermore, NaMLP-silenced plants had reduced TPI activities and better S. litura performance. Finally, OS-elicited NaMLP was dramatically reduced in JA-deficient AOC silencing and ethylene-reduced ACO-silencing plants, and the expression of NaMLP could be significantly induced by methyl jasmonate or ethephon alone, but dramatically amplified by co-treatment of both methyl jasmonate and ethephon. Thus, our results demonstrate that in addition to JA-regulated NaPI, and WRKY3/6-dependent NaKTI2, N. attenuata plants also up-regulates TPI activities via NaMLP, which confers S. litura resistance through JA and ethylene signaling pathways in a synergistic way.

Determination and prediction of the available energy and amino acids digestibility of full-fat soybean fed to growing pigs

Two experiments were conducted to determine the digestible energy and metabolizable energy contents, as well as the apparent ileal digestibility and standardized ileal digestibility of amino acids in full-fat soybean fed to growing pigs. Ten full-fat soybean samples were collected from different areas in China and used in two experiments in this study. In Exp. 1, 66 growing pigs (initial body weight = 18.48 ± 1.2 kg) were randomly allotted to 1 of 11 diets (n = 6) including a corn basal diet and 10 experimental diets formulated by replacing the corn with 30% full-fat soybean. In Exp. 2, 11 growing pigs (initial body weight = 50.45 ± 3.2 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in a 6 × 11 Youden square design with 11 diets and 6 periods. The diets included an N-free diet based on cornstarch and sucrose and 10 experimental diets formulated with full-fat soybeans as the sole source of amino acids. Chromic oxide was added into the diets as an indigestible maker to calculate the digestibility of the amino acids. Results showed that there was considerable variation in neutral detergent fiber, acid detergent fiber, and trypsin inhibitor contents in the 10 full-fat soybean samples with a coefficient of variation greater than 10%. On a dry matter basis, the averaged digestible energy and metabolizable energy values in the 10 full-fat soybean samples were 4,855 and 4,555 kcal/kg, respectively, both were positively correlated with the ether extract content. The best-fitted prediction equations for digestible energy and metabolizable energy of full-fat soybean were: digestible energy, kcal/kg = 3,472 + 94.87 × ether extract - 97.63 × ash (R2 = 0.91); metabolizable energy, kcal/kg = 3,443 + 65.11 × ether extract - 36.84 × trypsin inhibitor (R2 = 0.91). In addition, all full-fat soybean samples showed high apparent ileal digestibility and standardized ileal digestibility values in amino acids and were all within the range of previously published values. Those values significantly varied among different samples (P < 0.05) for most amino acids, except for glycine and proline. In conclusion, full-fat soybean is a high-quality protein ingredient with high ileal digestibility of amino acids when fed to growing pigs, and the metabolizable energy value of full-fat soybean could be predicted based on its ether extract and trypsin inhibitor contents.

Trypsin-like Inhibitor Domain (TIL)-Harboring Protein Is Essential for Aedes aegypti Reproduction

Cysteine-rich trypsin inhibitor-like domain (TIL)-harboring proteins are broadly distributed in nature but remain understudied in vector mosquitoes. Here we have explored the biology of a TIL domain-containing protein of the arbovirus vector Aedes aegypti, cysteine-rich venom protein 379 (CRVP379). CRVP379 was previously shown to be essential for dengue virus infection in Ae. aegypti mosquitoes. Gene expression analysis showed CRVP379 to be highly expressed in pupal stages, male testes, and female ovaries. CRVP379 expression is also increased in the ovaries at 48 h post-blood feeding. We used CRISPR-Cas9 genome editing to generate two mutant lines of CRVP379 with mutations inside or outside the TIL domain. Female mosquitoes from both mutant lines showed severe defects in their reproductive capability; mutant females also showed differences in their follicular cell morphology. However, the CRVP379 line with a mutation outside the TIL domain did not affect male reproductive performance, suggesting that some CRVP379 residues may have sexually dimorphic functions. In contrast to previous reports, we did not observe a noticeable difference in dengue virus infection between the wild-type and any of the mutant lines. The importance of CRVP379 in Ae. aegypti reproductive biology makes it an interesting candidate for the development of Ae. aegypti population control methods.

Protease Inhibitors from Plants as Therapeutic Agents- A Review

Plant-based diets are a great source of protease inhibitors (PIs). Two of the most well-known families of PIs are Bowman-Birk inhibitors (BBI) and Kunitz-type inhibitors (KTI). The first group acts mainly on trypsin, chymotrypsin, and elastase; the second is on serine, cysteine, and aspartic proteases. PIs can retard or inhibit the catalytic action of enzymes; therefore, they are considered non-nutritional compounds; nevertheless, animal studies and cell line experiments showed promising results of PIs in treating human illnesses such as obesity, cardiovascular diseases, autoimmune diseases, inflammatory processes, and different types of cancer (gastric, colorectal, breast, and lung cancer). Anticarcinogenic activity's proposed mechanisms of action comprise several inhibitory effects at different molecular levels, i.e., transcription, post-transcription, translation, post-translation, and secretion of cancer cells. This work reviews the potential therapeutic applications of PIs as anticarcinogenic and anti-inflammatory agents in human diseases and the mechanisms by which they exert these effects.

TcTI, a Kunitz-type trypsin inhibitor from cocoa associated with defense against pathogens

Protease inhibitors (PIs) are important biotechnological tools of interest in agriculture. Usually they are the first proteins to be activated in plant-induced resistance against pathogens. Therefore, the aim of this study was to characterize a Theobroma cacao trypsin inhibitor called TcTI. The ORF has 740 bp encoding a protein with 219 amino acids, molecular weight of approximately 23 kDa. rTcTI was expressed in the soluble fraction of Escherichia coli strain Rosetta [DE3]. The purified His-Tag rTcTI showed inhibitory activity against commercial porcine trypsin. The kinetic model demonstrated that rTcTI is a competitive inhibitor, with a Ki value of 4.08 × 10-7 mol L-1. The thermostability analysis of rTcTI showed that 100% inhibitory activity was retained up to 60 °C and that at 70-80 °C, inhibitory activity remained above 50%. Circular dichroism analysis indicated that the protein is rich in loop structures and β-conformations. Furthermore, in vivo assays against Helicoverpa armigera larvae were also performed with rTcTI in 0.1 mg mL-1 spray solutions on leaf surfaces, which reduced larval growth by 70% compared to the control treatment. Trials with cocoa plants infected with Mp showed a greater accumulation of TcTI in resistant varieties of T. cacao, so this regulation may be associated with different isoforms of TcTI. This inhibitor has biochemical characteristics suitable for biotechnological applications as well as in resistance studies of T. cacao and other crops.

Mechanism of low-frequency and high-frequency ultrasound-induced inactivation of soy trypsin inhibitors

In this study, the effect of ultrasonic frequency and power on the inactivation of soy trypsin inhibitors (TIs) was investigated to explore the ultrasound-induced inactivation mechanism. It was observed that 20 kHz and 355 kHz ultrasound have better inactivation efficiency than 1056 kHz. First-order rate constants for the inactivation process were obtained, which increased with increasing ultrasonic power at both 20 kHz and 355 kHz. For 20 kHz ultrasound, the formation of TI aggregates resulting from the physical effects of acoustic cavitation decreased the interactions between the active sites of TIs and trypsin, thus reducing the TI activity. For 355 kHz ultrasound, most of the methionine in the TIs was oxidised within 5 mins, resulting in a faster reduction of TI activity. Subsequent aggregation of TIs resulted in further TI inactivation. SDS-PAGE showed that neither disulphide bonds nor CC coupling were involved in the formation of aggregates.

Genetic architecture underlying the expression of eight α-amylase trypsin inhibitors

KEY MESSAGE

Wheat cultivars largely differ in the content and composition of ATI proteins, but heritability was quite low for six out of eight ATIs. The genetic architecture of ATI proteins is built up of few major and numerous small effect QTL. Amylase trypsin inhibitors (ATIs) are important allergens in baker's asthma and suspected triggers of non-celiac wheat sensitivity (NCWS) inducing intestinal and extra-intestinal inflammation. As studies on the expression and genetic architecture of ATI proteins in wheat are lacking, we evaluated 149 European old and modern bread wheat cultivars grown at three different field locations for their content of eight ATI proteins. Large differences in the content and composition of ATIs in the different cultivars were identified ranging from 3.76 pmol for ATI CM2 to 80.4 pmol for ATI 0.19, with up to 2.5-fold variation in CM-type and up to sixfold variation in mono/dimeric ATIs. Generally, heritability estimates were low except for ATI 0.28 and ATI CM2. ATI protein content showed a low correlation with quality traits commonly analyzed in wheat breeding. Similarly, no trends were found regarding ATI content in wheat cultivars originating from numerous countries and decades of breeding history. Genome-wide association mapping revealed a complex genetic architecture built of many small, few medium and two major quantitative trait loci (QTL). The major QTL were located on chromosomes 3B for ATI 0.19-like and 6B for ATI 0.28, explaining 70.6 and 68.7% of the genotypic variance, respectively. Within close physical proximity to the medium and major QTL, we identified eight potential candidate genes on the wheat reference genome encoding structurally related lipid transfer proteins. Consequently, selection and breeding of wheat cultivars with low ATI protein amounts appear difficult requiring other strategies to reduce ATI content in wheat products.

Detoxification of jatropha kernel meal to utilize it as aqua-feed

BACKGROUND

Jatropha is an oilseed crop with high kernel oil (55-58%) and protein (26-29%) contents, which makes it a good source of biodiesel and animal/aqua-feed. However, the presence of anti-nutritional toxins, such as phorbol esters, lectins, trypsin inhibitor, phytate, and saponins, restricts its use as feed. This paper describes chemical, ultraviolet (UV) radiation, and biological treatments for detoxification of jatropha kernel meal. Raw, defatted, and one-time and two-times mechanically expressed oil samples were analyzed for toxins. Chemical treatment involved heating with 90% methanol and 4% sodium hydroxide. UV treatment was carried out at UV light intensity of 53.4 mW cm^-2 for 30 min. For biological treatment, cell-free extract from Pseudomonas aeruginosa (strain PAO1) was mixed with kernel meal for detoxification.

RESULTS

Among treatments, chemical treatment was most effective in reducing all toxins, with phorbol esters in the range 0.034-0.052 mg g^-1 , lectin 0.082-10.766 mg g^-1 , trypsin inhibitor 10.499-11.350 mg g^-1 , phytate 2.475-5.769 mg g^-1 , and saponins 0.044-0.098 mg g^-1 . Biological treatment reduced all toxins except phytate, whereas UV treatment could not reduce any of toxins and, hence, cannot be used for aqua-feed preparation. Pellets prepared from chemically detoxified kernel meal with the least oil content (defatted) resulted in the highest strength (70.93 N).

CONCLUSION

Chemically treated jatropha kernel meal can be used for aqua-feed pellet preparation because of its low toxin content. The highest compressive strength was obtained for pellets with the least oil content (defatted). Biological treatment time must have been extended for many hours instead of 24 h. Jatropha kernel meal treated chemically can be recommended for aqua-feed manufacturing. © 2021 Society of Chemical Industry.

The Effects of Trypsin Inhibitor on Insulin Secretion Using Rat Pancreas in an Organ Bath

BACKGROUND/AIM

We developed an experimental method to reproduce insulin secretion from isolated rat pancreas preparations using an organ bath system. However, secretion of trypsin, another pancreatic enzyme, interferes with insulin production in such systems. We aimed to ascertain the minimum trypsin inhibitor (TI), dose for obtaining a sustained, stable rate of insulin secretion.

MATERIALS AND METHODS

The action of TI (1-10 μg/ml) on pancreatic preparations of male Wistar-Imamichi rats in organ bath experiments was assessed by measuring insulin, amylase, and trypsin activity.

RESULTS

The level of insulin outflow remained steady in the TI-treated samples, in contrast to that in the untreated control, where insulin secretion decreased over time. The level of amylase outflow did not change significantly. Trypsin activity was significantly lower in the TI-treated samples than in the control.

CONCLUSION

Even low concentrations of TI can maintain insulin secretion by inhibiting trypsin activity in organ bath experiments.

Synthesis and accumulation of amylase-trypsin inhibitors and changes in carbohydrate profile during grain development of bread wheat (Triticum aestivum L.)

BACKGROUND

Recent studies indicate that amylase-trypsin inhibitors (ATIs) and certain carbohydrates referred to as FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) play an important role in promoting wheat sensitivity. Hitherto, no study has investigated the accumulation of ATIs during the development of the wheat caryopsis. We collected caryopses of common wheat cv. 'Arnold' at eight different grain developmental stages to study compositional changes in ATI and FODMAP content.

RESULTS

The harvested caryopses were analysed for their size, protein and carbohydrate concentrations. ATIs were further characterized by MALDI-TOF MS, and their trypsin inhibition was evaluated by an enzymatic assay. The results showed that ATI accumulation started about 1 week after anthesis and subsequently increased steadily until physiological maturity. However, the biological activity of ATIs in terms of enzyme inhibition was not detectable before about 4 weeks after anthesis. Carbohydrate analysis revealed the abundance of short-chain fructans in early stages of grain development, whereas non-water-soluble carbohydrates increased during later developmental stages.

CONCLUSIONS

The results provide new insights into the complex metabolisms during grain filling and maturation, with particular emphasis on the ATI content as well as the inhibitory potential towards trypsin. The time lag between ATI accumulation and development of their biological activity is possibly attributed to the assembling of ATIs to dimers and tetramers, which seems to be crucial for their inhibitory potential.

Trypsin inhibitor content and activity of soaking water whey as waste in soy milk processing

Soybean soaking water whey (SWW) is obtained as the waste of soy milk production and mostly represents an environmental problem. The aim of this study was to assess the content of proteins and content and activity of trypsin inhibitors of fresh SWW, obtained during soy milk production. Two zones of Bowman-Birk trypsin inhibitors (BBI) were detected. One was identified as a monomeric form of BBI (0.61-2.93%) and the other one was identified as a polymeric form of BBI (0.45-3.33%). The degree of BBI extraction (1.88-5.49%) was influenced by the soybean genotype and the grain size, i.e. it increased with increasing grain size. Kunitz trypsin inhibitor was not detected. Total proteins were found in traces in SWW (0.03-0.06%). Low residual trypsin inhibitor activity (0.32-0.55%) suggested that SWW can potentially be applied for preparing food or feed. In that case it will not be waste but a cheap functional supplement with BBI as a biologically active component.

Transgenic Cry1Ac/CpTI cotton assessment finds no detrimental effects on the insect predator Chrysoperla sinica

The widespread commercialization of genetically modified (GM) cotton makes it important to assess the potential impact of this recombinant crop on non-target organisms. As important natural enemies of cotton field predators, green lacewing Chrysoperla sinica larvae are exposed to Bt insecticidal proteins expressed by GM cotton by feeding on herbivorous pests, and adults are directly exposed to Bt proteins by cotton pollen consumption. However, potential impacts of transgenic Bt cotton on C. sinica remain unclear. In this study, we evaluated the effects of two transgenic cotton varieties, CCRI41 and CCRI45, which express Cry1Ac (Bt toxin) and CpTI (Cowpea Trypsin Inhibitor), on C. sinica larvae and adults. After being fed with cotton aphids Aphis gossypii reared on transgenic cotton, the survival rate, developmental duration, pupation rate, and emergence rate of larvae were not adversely affected. After being fed two types of transgenic cotton pollen, the 7-day weight of adults and the preoviposition period and the cumulative oviposition of females were not significantly different from control specimen. Taken together, these results indicate that the potential risks of the two tested GM cotton varieties for the predator C. sinica are negligible. CAPSULE: Our study indicated that GM cotton varieties CCRI41 and CCRI45 have no adverse effects on insect predator C. sinica.

NaKTI2, a Kunitz trypsin inhibitor transcriptionally regulated by NaWRKY3 and NaWRKY6, is required for herbivore resistance in Nicotiana attenuata

KEY MESSAGE

Here, we reported that a pathogen- and herbivore-induced Kunitz trypsin inhibitor gene, NaKTI2, is required for herbivore resistance, and transcriptionally regulated mainly by NaWRKY3 and NaWRKY6 but not Jasmonate signaling. Plant protease inhibitor (PI) occurs widely in plant species, and is considered as an important part of plant defense arsenal against herbivores. Transcriptome analysis of Nicotiana attenuata leaves revealed that a Kunitz trypsin inhibitor gene, NaKTI2, was highly elicited after inoculation of Alternaria alternata (tobacco pathotype). However, the roles of NaKTI2 in pathogen- and herbivore resistance and its regulation were unclear. NaKTI2 had typical domains of Kunitz trypsin inhibitors and exhibited a high level of trypsin protease inhibitor activities when transiently over-expressed. The transcripts of NaKTI2 could be induced by A. alternata and Spodoptera litura oral secretions (OS). Silencing NaKTI2 via virus-induced gene silencing technique has no influence on lesion diameters developed on N. attenuata leaves after A. alternata inoculation, but S. litura larvae gained more mass and had higher survivorship on NaKTI2-silenced plants. Meanwhile, the expression of NaPI, a PI gene essential for herbivore resistance previously identified in N. attenuata, was not affected in NaKTI2-silenced plants. Unlike NaPI, which was predominantly regulated by jasmonate (JA) signaling, OS-elicited NaKTI2 transcripts were only slightly reduced in JA-deficient plants, but were dramatically decreased in NaWRKY3- and NaWRKY6- silenced plants, respectively. Further electromobility shift assays indicated that NaWRKY3 and NaWRKY6 could directly bind to the promoter regions of NaKTI2 in vitro. Taken together, our results demonstrate that in addition to NaPI, NaKTI2, a pathogen- and herbivore-induced Kunitz trypsin inhibitor gene, is also required for herbivore resistance, and mainly regulated by NaWRKY3 and NaWRKY6.

Measuring the KD of Protein-Ligand Interactions Using Microscale Thermophoresis

Microscale thermophoresis (MST) has become a widely used technique to determine the KD or EC50 of protein-ligand interactions. The method exploits the tendency of macromolecules to migrate along a thermal gradient (i.e., thermophoresis). Differences in thermophoresis as a function of the liganded state of a macromolecule can be measured and assembled into a binding curve that can be analyzed to yield KD. In this protocol, we outline a simple experiment designed for new MST users, with the goal of using readily available, inexpensive materials to plan, execute, and analyze an MST experiment.

Characterization of ecotin homologs from Campylobacter rectus and Campylobacter showae

Ecotin, first described in Escherichia coli, is a potent inhibitor of a broad range of serine proteases including those typically released by the innate immune system such as neutrophil elastase (NE). Here we describe the identification of ecotin orthologs in various Campylobacter species, including Campylobacter rectus and Campylobacter showae residing in the oral cavity and implicated in the development and progression of periodontal disease in humans. To investigate the function of these ecotins in vitro, the orthologs from C. rectus and C. showae were recombinantly expressed and purified from E. coli. Using CmeA degradation/protection assays, fluorescence resonance energy transfer and NE activity assays, we found that ecotins from C. rectus and C. showae inhibit NE, factor Xa and trypsin, but not the Campylobacter jejuni serine protease HtrA or its ortholog in E. coli, DegP. To further evaluate ecotin function in vivo, an E. coli ecotin-deficient mutant was complemented with the C. rectus and C. showae homologs. Using a neutrophil killing assay, we demonstrate that the low survival rate of the E. coli ecotin-deficient mutant can be rescued upon expression of ecotins from C. rectus and C. showae. In addition, the C. rectus and C. showae ecotins partially compensate for loss of N-glycosylation and increased protease susceptibility in the related pathogen, Campylobacter jejuni, thus implicating a similar role for these proteins in the native host to cope with the protease-rich environment of the oral cavity.

Label-free analytical performances of a peptide-based QCM biosensor for trypsin

A label-free biosensor was fabricated for the detection of trypsin by using a peptide-functionalized quartz crystal microbalance gold electrode. The synthetized peptide chains were immobilized tightly on the QCM electrode via a self-assembly method, which formed a thin and approximate rigid layer of peptides. The detection signal was achieved by calculating the mass changes on the QCM electrode because the peptide chains could be specifically cleaved in the carboxyl terminuses of arginine and lysine by trypsin. When gold nanoparticles were coupled to the peptide chains, the sensing signal would be amplified 10.9 times. Furthermore, the sensor interface shows a lower resonance resistance change when the peptide chain is immobilized horizontally. Independent detections in parallel on different electrodes have a wide linear range. Under the optimum conditions, the signal-amplified biosensor allowed the measurement of trypsin over the range of 0-750 ng mL-1 with a detection limit of 8.6 ng mL-1. Moreover, for screening the inhibitor of trypsin, the IC50 values were obtained to be 1.85 μg mL-1 for benzamidine hydrochloride and 20.5 ng mL-1 for the inhibitor from soybean.

Structural and functional relationship of Cassia obtusifolia trypsin inhibitor to understand its digestive resistance against Pieris rapae

Although digestive resistance of Kunitz protease inhibitors has been reported extensively, the molecular mechanism is not well established. In the present study, the first X-ray structure of Cassia obtusifolia trypsin inhibitor (COTI), a member of Kunitz protease inhibitors, was solved at a resolution of 1.9 Å. The structure adopted a classic β-trefoil fold with the inhibitory loop protruding from the hydrophobic core. The role of Phe139, a unique residue in Kunitz protease inhibitors, and Arg63 in the COTI structure was verified by F139A and R63E mutants. COTI was a specific inhibitor of bovine trypsin and the result was also verified by COTI-trypsin complex formation. Meanwhile, COTI showed equivalent inhibitory activity with that of soybean trypsin inhibitor against bovine trypsin and midgut trypsin from Pieris rapae. The F139 and R63E mutants further indicated that inhibitory specificity and efficiency of COTI were closely related to the global framework, the conformation and the amino acid composition of reactive loop. Finally, a midgut trypsin from P. rapae (PrSP40), which might be involve in the food digestion, was proposed to be a potential target of COTI and might be a promising target for future crop-protection strategy. The results supported the digestive resistance of COTI.

Effect of Instant Controlled Pressure-Drop on the Non-Nutritional Compounds of Seeds and Sprouts of Common Black Bean (Phaseolus vulgaris L.)

The common bean is an important caloric-protein food source. However, its nutritional value may be affected by the presence of non-nutritional compounds, which decrease the assimilation of some nutrients; however, at low concentrations, they show a beneficial effect. Germination and treatment by controlled pressure-drop (DIC, French acronym of Détente Instantanée Contrôlée) are methods that modify the concentration of these components. The objective of this work was to evaluate the change in the non-nutritional composition of bean seeds and sprouts by DIC treatment. The results show that with the germination, the concentration of phenolic and tannin compounds increased 99% and 73%, respectively, as well as the quantity of saponins (65.7%), while phytates and trypsin inhibitors decreased 26% and 42%, respectively. When applying the DIC treatment, the content of phytates (23-29%), saponins (44%) and oligosaccharides increased in bean sprouts and decreased phenolic compounds (4-14%), tannins (23% to 72%), and trypsin inhibitors (95.5%), according to the pressure and time conditions applied. This technology opens the way to new perspectives, especially to more effective use of legumes as a source of vegetable protein or bioactive compounds.

The pathogen Moniliophthora perniciosa promotes differential proteomic modulation of cacao genotypes with contrasting resistance to witches´ broom disease

BACKGROUND

Witches' broom disease (WBD) of cacao (Theobroma cacao L.), caused by Moniliophthora perniciosa, is the most important limiting factor for the cacao production in Brazil. Hence, the development of cacao genotypes with durable resistance is the key challenge for control the disease. Proteomic methods are often used to study the interactions between hosts and pathogens, therefore helping classical plant breeding projects on the development of resistant genotypes. The present study compared the proteomic alterations between two cacao genotypes standard for WBD resistance and susceptibility, in response to M. perniciosa infection at 72 h and 45 days post-inoculation; respectively the very early stages of the biotrophic and necrotrophic stages of the cacao x M. perniciosa interaction.

RESULTS

A total of 554 proteins were identified, being 246 in the susceptible Catongo and 308 in the resistant TSH1188 genotypes. The identified proteins were involved mainly in metabolism, energy, defense and oxidative stress. The resistant genotype showed more expressed proteins with more variability associated with stress and defense, while the susceptible genotype exhibited more repressed proteins. Among these proteins, stand out pathogenesis related proteins (PRs), oxidative stress regulation related proteins, and trypsin inhibitors. Interaction networks were predicted, and a complex protein-protein interaction was observed. Some proteins showed a high number of interactions, suggesting that those proteins may function as cross-talkers between these biological functions.

CONCLUSIONS

We present the first study reporting the proteomic alterations of resistant and susceptible genotypes in the T. cacao x M. perniciosa pathosystem. The important altered proteins identified in the present study are related to key biologic functions in resistance, such as oxidative stress, especially in the resistant genotype TSH1188, that showed a strong mechanism of detoxification. Also, the positive regulation of defense and stress proteins were more evident in this genotype. Proteins with significant roles against fungal plant pathogens, such as chitinases, trypsin inhibitors and PR 5 were also identified, and they may be good resistance markers. Finally, important biological functions, such as stress and defense, photosynthesis, oxidative stress and carbohydrate metabolism were differentially impacted with M. perniciosa infection in each genotype.

Plasmid DNA nicking- a Novel Activity of Soybean Trypsin Inhibitor and Bovine Aprotinin

Protease inhibitors, such as trypsin inhibitor, serum alpha-1 antitrypsin, or liver aprotinin, are a class of proteins that competitively bind and block the catalytic activity of proteolytic enzymes with wide ranging biological functions. A significant number of protease inhibitors have also been shown to possess antimicrobial activity, presumed to contribute in defense against pathogenic microorganisms as plants with higher levels of protease inhibitors tend to exhibit increased resistance towards pathogens. Two proposed mechanisms for the antimicrobial activity are combating microbial proteases that play roles in disease development and disruption of microbial cell wall & membrane necessary for survival. Here we show for the first time a novel activity of soybean trypsin inhibitor and bovine aprotinin that they nick supercoiled, circular plasmid DNA. A number of experiments conducted to demonstrate the observed DNA nicking activity is inherent, rather than a co-purified, contaminating nuclease. The nicking of the plasmid results in markedly reduced efficiencies in transformation of E. coli and transfection of HEK293T cells. Thus, this work reveals yet a new mechanism for the antimicrobial activity by protease inhibitors.

A trypsin inhibitor-like protein secreted by Cotesia vestalis teratocytes inhibits hemolymph prophenoloxidase activation of Plutella xylostella

To establish successful infections, endoparasitoid wasps must develop strategies to evade immune responses of the host. Here, we identified and characterized a teratocytes-expressed gene encoding a trypsin inhibitor-like protein containing a cysteine-rich domain from Cotesia vestalis, CvT-TIL. CvT-TIL had a high expression level during the later developmental stage of teratocytes and was secreted into host hemolymph. Further experiments showed CvT-TIL strongly suppressed the prophenoloxidase activation of host hemolymph in a dose-dependent manner by interacting with PxPAP3 of PO cascade. Our results not only provide evidence for an inhibition between CvT-TIL gene and the host's melanization activity, but also expand our knowledge about the mechanisms by which parasitoids regulate humoral immunity of the host.

Structural characterization of PPTI, a kunitz-type protein from the venom of Pseudocerastes persicus

The main purpose of this report is to investigate the structural property and new potential function of PPTI (Pseudocerastes Persicus Trypsin Inhibitor), a kunitz-type protein with inhibitory effect against trypsin proteolytic activity. Besides kunitz-type serine protease inhibitors, PPTI shows clear-cut similarities with dendrotoxins (DTXs), the other kunitz-type protein subfamily. The most important reason is the presence of functionally important residues of DTXs at correspondingly the same positions in PPTI. As such, we proposed the new ability of PPTI for inhibiting voltage-gated potassium channels and consequently its dual functionality. At first, we determined the solution structure of PPTI via Nuclear Magnetic Resonance (NMR) spectroscopy. Then by homology modeling, we constructed the model structure of trypsin-PPTI complex to confirm the same interaction pattern as trypsin-BPTI at complex interface. Finally, by Brownian dynamics (BD) simulations of PPTI NMR derived ensemble structure as ligand against homology model of human Kv1.1 potassium channel as receptor, we evaluated the potential DTX-like activity of PPTI. The results of our study support the proposed dual functionality of PPTI.

A fluorometric sensing method for sensitive detection of trypsin and its inhibitor based on gold nanoclusters and gold nanoparticles

In this work, a facile, label-free, and sensitive fluorometric strategy for detection of trypsin and its inhibitor was established on the basis of the fluorescence resonance energy transfer (FRET) between mercaptoundecanoic acid functionalized gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs) via protamine as a bridge. Protamine can trigger the aggregation of AuNPs and link AuNCs with aggregated AuNPs through electrostatic interaction. Compared with monodisperse AuNPs, the UV-vis absorption band of aggregated AuNPs overlapped considerably with the emission spectrum of AuNCs. Thus, the fluorescence of AuNCs was obviously quenched by the aggregated AuNPs through FRET. In the presence of trypsin, protamine was hydrolyzed into small fragments, leading to the deaggregation of AuNPs and breaking of the short distance between AuNPs and AuNCs, so the FRET process was inhibited, and the fluorescence of AuNCs was recovered. The increase in the fluorescence intensity of AuNCs was directly related to the amount of trypsin. Hence trypsin can be determined on the basis of the variation of fluorescence intensity, with a linear range of 5-5000 ng mL-1 and a detection limit of 1.9 ng mL-1. In addition, this system was used for the detection of trypsin inhibitor by application of the inhibitor isolated from soybean as a model. The sensing method was applied for trypsin detection in human urine and commercial multienzyme tablet samples with satisfactory results. Graphical abstract ᅟ.

Suppression of Plant Defenses by Herbivorous Mites Is Not Associated with Adaptation to Host Plants

Some herbivores suppress plant defenses, which may be viewed as a result of the coevolutionary arms race between plants and herbivores. However, this ability is usually studied in a one-herbivore-one-plant system, which hampers comparative studies that could corroborate this hypothesis. Here, we extend this paradigm and ask whether the herbivorous spider-mite Tetranychus evansi, which suppresses the jasmonic-acid pathway in tomato plants, is also able to suppress defenses in other host plants at different phylogenetic distances from tomatoes. We test this using different plants from the Solanales order, namely tomato, jimsonweed, tobacco, and morning glory (three Solanaceae and one Convolvulaceae), and bean plants (Fabales). First, we compare the performance of T. evansi to that of the other two most-commonly found species of the same genus, T. urticae and T. ludeni, on several plants. We found that the performance of T. evansi is higher than that of the other species only on tomato plants. We then showed, by measuring trypsin inhibitor activity and life history traits of conspecific mites on either clean or pre-infested plants, that T. evansi can suppress plant defenses on all plants except tobacco. This study suggests that the suppression of plant defenses may occur on host plants other than those to which herbivores are adapted.

Analysis of Kunitz inhibitors from plants for comprehensive structural and functional insights

Legume Kunitz type trypsin inhibitor (KTI) family is one of the most versatile families of proteins. A typical KTI features a single peptide folded in β-trefoil manner, with the molecular weight about 20-22kDa and two disulphide bonds. The members are known to inhibit a wide range of serpins proteases at the same time many of them possess unique features. Copaifera langsdorffii Trypsin inhibitor (CTI) has a β-trefoil fold made up of two non-covalently bound polypeptide chains with only a single disulfide bridge. Delonix regia Trypsin inhibitor (DrTI) has one amino acid insertion between P1 and P2 of the reactive site distorting its conformation. Bauhinia bauhinioides Cruzipain inhibitor (BbCI) has a conservative β-trefoil fold but lacks disulfide bonds. Such subtle differences in structures make Kunitz inhibitors different from other inhibitor families. Most of the studies on these inhibitors are focused towards their proposed role in defense from insect pests and wounding but their exact physiological role in nature is still uncharted. Thus, it would be very interesting to closely analyze the structural details of these inhibitors in order to ascertain their biological role and other fascinating applications.

Comparative transcriptome analysis provides insights of anti-insect molecular mechanism of Cassia obtusifolia trypsin inhibitor against Pieris rapae

Pieris rapae, a serious Lepidoptera pest of cultivated crucifers, utilizes midgut enzymes to digest food and detoxify secondary metabolites from host plants. A recombinant trypsin inhibitor (COTI) from nonhost plant, Cassia obtusifolia, significantly decreased activities of trypsin-like proteases in the larval midgut on Pieris rapae and could suppress the growth of larvae. In order to know how COTI took effect, transcriptional profiles of P. rapae midgut in response to COTI was studied. A total of 51,544 unigenes were generated and 45.86% of which had homologs in public databases. Most of the regulated genes associated with digestion, detoxification, homeostasis, and resistance were downregulated after ingestion of COTI. Meanwhile, several unigenes in the integrin signaling pathway might be involved in response to COTI. Furthermore, using comparative transcriptome analysis, we detected differently expressing genes and identified a new reference gene, UPF3, by qRT-polymerase chain reaction (PCR). Therefore, it was suggested that not only proteolysis inhibition, but also suppression of expression of genes involved in metabolism, development, signaling, and defense might account for the anti-insect resistance of COTI.

Effects of Bacillus fermentation on the protein microstructure and anti-nutritional factors of soybean meal

This study evaluated the effects of Bacillus fermentation on soybean meal protein (SBMP) microstructure and major anti-nutritional factors (ANFs) in soybean meal (SBM). The Bacillus siamensis isolate JL8 producing high yield of protease at 519·1 U g-1 was selected for the laboratory production of fermented soybean meal (FSBM). After 24 h fermentation, the FSBM showed better properties compared with those of SBM, the ANFs such as glycinin, β-conglycinin and trypsin inhibitor significantly decreased by 86·0, 70·3 and 95·01%, while in vitro digestibility and absorbability increased by 8·7 and 18·9% respectively. Scanning electron microscopy (SEM) image of fermented soybean meal protein showed smaller aggregates and looser network than that of SBMP. Secondary structure examination of proteins revealed fermentation significantly decreased the content of β-sheet structure by 43·2% and increased the random coil structure by 59·9%. It is demonstrated that Bacillus fermentation improved the nutritional quality of SBM through degrading ANFs and changing the microstructure of SBMP.

SIGNIFICANCE AND IMPACT OF THE STUDY

There is limited information about the structural property changes of soybean protein during fermentation. In this study, physicochemical analysis of soybean meal protein showed evidence that the increase in in vitro digestibility and absorbability of fermented soybean meal reflected the decrease in β-conformation and destruction of original structure in soybean meal protein. The results directly gained the understanding of nutritional quality improvement of soybean meal by Bacillus fermentation, and supply the potential use of Bacillus siamensis for fermented soybean meal production.

Interfering with the high-affinity interaction between wheat amylase trypsin inhibitor CM3 and toll-like receptor 4: in silico and biosensor-based studies

Wheat amylase/trypsin bi-functional inhibitors (ATIs) are protein stimulators of innate immune response, with a recently established role in promoting both gastrointestinal and extra-gastrointestinal inflammatory syndromes. These proteins have been reported to trigger downstream intestinal inflammation upon activation of TLR4, a member of the Toll-like family of proteins that activates signalling pathways and induces the expression of immune and pro-inflammatory genes. In this study, we demonstrated the ability of ATI to directly interact with TLR4 with nanomolar affinity, and we kinetically and structurally characterized the interaction between these macromolecules by means of a concerted approach based on surface plasmon resonance binding analyses and computational studies. On the strength of these results, we designed an oligopeptide capable of preventing the formation of the complex between ATI and the receptor.

Application and bioactive properties of CaTI, a trypsin inhibitor from Capsicum annuum seeds: membrane permeabilization, oxidative stress and intracellular target in phytopathogenic fungi cells

BACKGROUND

During the last few years, a growing number of antimicrobial peptides have been isolated from plants and particularly from seeds. Recent results from our laboratory have shown the purification of a new trypsin inhibitor, named CaTI, from chilli pepper (Capsicum annuum L.) seeds. This study aims to evaluate the antifungal activity and mechanism of action of CaTI on phytopathogenic fungi and detect the presence of protease inhibitors in other species of this genus.

RESULTS

Our results show that CaTI can inhibit the growth of the phytopathogenic fungi Colletotrichum gloeosporioides and C. lindemuthianum. CaTI can also permeabilize the membrane of all tested fungi. When testing the inhibitor on its ability to induce reactive oxygen species, an induction of reactive oxygen species (ROS) and nitric oxide (NO) particularly in Fusarium species was observed. Using CaTI coupled to fluorescein isothiocyanate (FITC), it was possible to determine the presence of the inhibitor inside the hyphae of the Fusarium oxysporum fungus. The search for protease inhibitors in other Capsicum species revealed their presence in all tested species.

CONCLUSION

This paper shows the antifungal activity of protease inhibitors such as CaTI against phytopathogenic fungi. Antimicrobial peptides, among which the trypsin protease inhibitor family stands out, are present in different species of the genus Capsicum and are part of the chemical arsenal that plants use to defend themselves against pathogens. © 2017 Society of Chemical Industry.

A case of neofunctionalization of a Putranjiva roxburghii PNP protein to trypsin inhibitor by disruption of PNP-UDP domain through an insert containing inhibitory site

The attainment of new function by a protein is achieved through convergent/divergent evolution. In present work, the sequence analysis of a 34kDa protein from Putranjiva roxburghii, earlier reported as a potent trypsin inhibitor, showed resemblance to some of the wound inducible and vegetative storage proteins. A detailed sequence analysis revealed that these proteins belong to PNP-UDP family. In case of P. roxburghii protein, an approximately 46 residue insert disrupts the PNP domain. Similar disruption of PNP domain is observed in related plant proteins. The characterization of recombinant full length and truncated (without 46 residue insert) forms of P. roxburghii PNP family protein (PRpnp) unraveled that trypsin inhibitory active site is located within the insert. The truncated form containing uninterrupted PNP domain showed strong PNP enzymatic activity where it hydrolyzed the N-glycosidic bond of inosine and guanosine. The full length protein, however, showed weak PNP enzyme activity which may be due to presence of the insert. These results indicate towards the neofunctionalization of PRpnp to a potent trypsin inhibitor through an insert containing inhibitory residue to cater to the needs of plant defense. The similar wound inducible and vegetative storage proteins may have also evolved due to evolutionary needs.

Biophysical insight into structure-function relation of Allium sativum Protease Inhibitor by thermal, chemical and pH-induced modulation using comprehensive spectroscopic analysis

In this study, we have analyzed the structural and functional changes in the nature of Allium sativum Protease Inhibitor (ASPI) on undergoing various denaturation with variable range of pH, temperature and urea (at pH 8.2). ASPI being anti-tryptic in nature has native molecular mass of ∼15kDa. The conformational stability, functional parameters and their correlation were estimated under different conditions using circular dichroism, fluorescence and activity measurements. ASPI was found to fall in belongs to α+β protein. It demonstrated structural and functional stability in the pH range 5.0-12.0 and up to70°C temperature. Further decrease in pH and increase in temperature induces unfolding followed by aggregation. Chemical induced denaturation was found to be cooperative and transitions were reversible and sigmoid. T_m (midpoint of denaturation), ΔC_p (constant pressure heat capacity change) and ΔH_m (van't Hoff enthalpy change at T_m were calculated to be 41.25±0.2°C, 1.3±0.07kcalmol^-1K^-1 and 61±2kcalmol^-1 respectively for thermally denatured ASPI earlier. The reversibility of the protein was confirmed for both thermally and chemically denatured ASPI. The results obtained from trypsin inhibitory activity assay and structural studies are found to be in a significant correlation and hence established structure-function relationship of ASPI.

Evidence for Ancient Origins of Bowman-Birk Inhibitors from Selaginella moellendorffii

Bowman-Birk Inhibitors (BBIs) are a well-known family of plant protease inhibitors first described 70 years ago. BBIs are known only in the legume (Fabaceae) and cereal (Poaceae) families, but peptides that mimic their trypsin-inhibitory loops exist in sunflowers (Helianthus annuus) and frogs. The disparate biosynthetic origins and distant phylogenetic distribution implies these loops evolved independently, but their structural similarity suggests a common ancestor. Targeted bioinformatic searches for the BBI inhibitory loop discovered highly divergent BBI-like sequences in the seedless, vascular spikemoss Selaginella moellendorffii Using de novo transcriptomics, we confirmed expression of five transcripts in S. moellendorffii whose encoded proteins share homology with BBI inhibitory loops. The most highly expressed, BBI3, encodes a protein that inhibits trypsin. We needed to mutate two lysine residues to abolish trypsin inhibition, suggesting BBI3's mechanism of double-headed inhibition is shared with BBIs from angiosperms. As Selaginella belongs to the lycopod plant lineage, which diverged ∼200 to 230 million years before the common ancestor of angiosperms, its BBI-like proteins imply there was a common ancestor for legume and cereal BBIs. Indeed, we discovered BBI sequences in six angiosperm families outside the Fabaceae and Poaceae. These findings provide the evolutionary missing links between the well-known legume and cereal BBI gene families.

A Bowman-Birk protease inhibitor purified, cloned, sequenced and characterized from the seeds of Maclura pomifera (Raf.) Schneid

A new BBI-type protease inhibitor with remarkable structural characteristics was purified, cloned, and sequenced from seeds of Maclura pomifera , a dicotyledonous plant belonging to the Moraceae family. In this work, we report a Bowman-Birk inhibitor (BBI) isolated, purified, cloned, and characterized from Maclura pomifera seeds (MpBBI), the first of this type from a species belonging to Moraceae family. MpBBI was purified to homogeneity by RP-HPLC, total RNA was extracted from seeds of M. pomifera, and the 3'RACE-PCR method was applied to obtain the cDNA, which was cloned and sequenced. Peptide mass fingerprinting (PMF) analysis showed correspondence between the in silico-translated protein and MpBBI, confirming that it corresponds to a new plant protease inhibitor. The obtained cDNA encoded a polypeptide of 65 residues and possesses 10 cysteine residues, with molecular mass of 7379.27, pI 6.10, and extinction molar coefficient of 9105 M^-1 cm^-1. MpBBI inhibits strongly trypsin with K _i in the 10^-10 M range and was stable in a wide array of pH and extreme temperatures. MpBBI comparative modeling was applied to gain insight into its 3D structure and highlighted some distinguishing features: (1) two non-identical loops, (2) loop 1 (CEEESRC) is completely different from any known BBI, and (3) the amount of disulphide bonds is also different from any reported BBI from dicot plants.

A potent bidirectional promoter from the monocot cereal Eleusine coracana

Ragi bifunctional α-amylase-trypsin inhibitor (RBI) of Eleusine coracana (L.) Gaertn. (finger millet) simultaneously inhibits α-amylase and trypsin. In continuation of previous work on the cloning, expression and characterization of RBI, a bidirectional promoter from finger millet was explored on the basis of experimental observations. Two trypsin inhibitors were identified while purifying RBI from a trypsin-Sepharose column eluent. Using an FPLC gel filtration column, these three inhibitors were purified to homogeneity and subjected to MALDI-TOF-TOF-MS/MS analysis and N-terminal sequencing. Both ragi trypsin inhibitors (RTIs) showed the same N-terminal sequence and considerable sequence similarity to RBI, indicating the presence of a multigene protease inhibitor family in finger millet. To gain insight into the evolution of these genes, the upstream region of RBI was explored by Genome Walking. Interestingly, on sequencing, a genome walking product of ∼1 Kb showed presence of an N-terminal RBI specific primer sequence twice but in opposite directions and leaving an intervening region of ∼0.9 Kb. The intervening region was presumed to represent an E. coracana bidirectional promoter (EcBDP), intuitively having a divergent RBI-RTI gene pair at two sides. For assaying the bidirectionality of promoter activity, a dual reporter GUS-GFP vector construct was made for plant expression containing the reporter genes at two ends of EcBDP, which was used to transform Agrobacterium tumefaciens LBA 4404. Transient plant transformation by recombinant Agrobacterium cells was carried out in onion scale epidermal cells and finger millet seedling leaves. Simultaneous expression of GUS and GFP under EcBDP established it as a potent natural bidirectional promoter from monocot origin, thereby potentially having vast application in cereal gene manipulations. In addition, inducibility of the EcBDP by either abscisic acid or cold treatment, as determined by transient transformation in onion, would substantiate more precise control of gene expression to mitigate the effects of adverse environmental conditions.

Higher Activities of Defense-Associated Enzymes may Contribute to Greater Resistance of Manchurian Ash to Emerald Ash Borer Than A closely Related and Susceptible Congener

Emerald ash borer (EAB) is an invasive beetle native to Asia that infests and kills ash (Fraxinus spp.) in North America. Previous experiments indicated that larvae feeding on co-evolved, resistant Manchurian ash (F. mandshurica) have increased antioxidant and quinone-protective enzyme activities compared to larvae feeding on susceptible North American species. Here, we examined mechanisms of host-generated oxidative and quinone-based stress and other putative defenses in Manchurian ash and the closely related and chemically similar, but susceptible, black ash (F. nigra), with and without exogenous application of methyl jasmonate (MeJA) to induce resistance mechanisms. Peroxidase activities were 4.6-13.3 times higher in Manchurian than black ash, although both species appeared to express the same three peroxidase isozymes. Additionally, peroxidase-mediated protein cross-linking activity was stronger in Manchurian ash. Polyphenol oxidase, β-glucosidase, chitinase, and lipoxygenase activities also were greater in Manchurian ash, but only lipoxygenase activity increased with MeJA application. Phloem H₂O₂ levels were similar and were increased by MeJA application in both species. Lastly, trypsin inhibitor activity was detected in methanol and water extracts that were not allowed to oxidize, indicating the presence of phenolic-based trypsin inhibitors. However, no proteinaceous trypsin inhibitor activity was detected in either species. In response to MeJA application, Manchurian ash had higher trypsin inhibitor activity than black ash using the unoxidized water extracts, but no treatment effects were detected using methanol extracts. Based on these results we hypothesize that peroxidases, lignin polymerization, and quinone generation contribute to the greater resistance to EAB displayed by Manchurian ash.

The Potential Use of Fermented Chickpea and Faba Bean Flour as Food Ingredients

Apart from being a rich and inexpensive protein source, legumes provide essential vitamins, minerals and dietary fibre. Considering the nutritional benefits, legumes flour can potentially be incorporated in the development of new products. The aim of this study was to investigate whether fermentation affects the protein content, in vitro protein digestibility, trypsin inhibitor activity and the functionality of proteins in faba bean, desi and kabuli chickpea. Australian grown chickpea and faba bean were selected and initially soaked, de-hulled, dried and milled into flour. This was fermented with lyophilised yoghurt cultures in a 30 °C orbital shaker for 16 h. While protein contents in fermented desi and kabuli flour were lower than their raw counterparts (p > 0.05), it was significantly higher in fermented faba bean. A significant increase (9.5%) in in vitro protein digestibility was found in fermented desi. Trypsin inhibitor activity in fermented desi, kabuli and faba bean reduced by 2.7, 1.1 and 4.7%, respectively (p > 0.05). Overall, the in vitro protein digestibility in flour samples increased, while simultaneously reducing the trypsin inhibitor activity. The water absorption capacity of the fermented kabuli flour significantly increased by 11.3%. All fermented flour samples had significantly higher oil absorption capacity than their corresponding raw flour that was likely due to increased insoluble hydrophobic protein. Although, the foaming capacity in all fermented flour samples was significantly lower than their respective raw samples, only fermented desi and faba bean flour showed lower foaming stability (p > 0.05). The present study suggests that fermented legume flour could fulfill the demand for innovative products of higher nutritional value.

Trypsin from unicorn leatherjacket (Aluterus monoceros) pyloric caeca: purification and its use for preparation of fish protein hydrolysate with antioxidative activity

BACKGROUND

Fish proteases, especially trypsin, could be used to prepare fish protein hydrolysates with antioxidative activities. In this study, trypsin from the pyloric caeca of unicorn leatherjacket was purified by ammonium sulfate precipitation and soybean trypsin inhibitor (SBTI)-Sepharose 4B affinity chromatography. Hydrolysate from Indian mackerel protein isolate with different degrees of hydrolysis (20, 30 and 40% DH) was prepared using the purified trypsin, and antioxidative activities (1,1-diphenyl-2-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical-scavenging activities, ferric-reducing antioxidant power and ferrous-chelating activity) of the hydrolysate were determined.

RESULTS

Trypsin was purified 26.43-fold with a yield of 13.43%. The purified trypsin had a molecular weight (MW) of 23.5 kDa and optimal activity at pH 8.0 and 55 °C. It displayed high stability in the pH range of 6.0-11.0 and was thermally stable up to 50 °C. Both SBTI (0.05 mmol L(-1)) and N-p-tosyl-L-lysine-chloromethylketone (5 mmol L(-1)) completely inhibited trypsin activity. Antioxidative activities of the hydrolysate from Indian mackerel protein isolate increased with increasing DH up to 40% (P < 0.05). Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis, the hydrolysate with 40% DH had a MW lower than 6.5 kDa.

CONCLUSION

The purified protease from unicorn leatherjacket pyloric caeca was identified as trypsin based on its ability to hydrolyze a specific synthetic substrate and the response to specific trypsin inhibitors. The purified trypsin could hydrolyze Indian mackerel protein isolate, and the resulting hydrolysate exhibited antioxidative activity depending on its DH.

Progress and gaps in understanding mechanisms of ash tree resistance to emerald ash borer, a model for wood-boring insects that kill angiosperms

We review the literature on host resistance of ash to emerald ash borer (EAB, Agrilus planipennis), an invasive species that causes widespread mortality of ash. Manchurian ash (Fraxinus mandshurica), which coevolved with EAB, is more resistant than evolutionarily naïve North American and European congeners. Manchurian ash was less preferred for adult feeding and oviposition than susceptible hosts, more resistant to larval feeding, had higher constitutive concentrations of bark lignans, coumarins, proline, tyramine and defensive proteins, and was characterized by faster oxidation of phenolics. Consistent with EAB being a secondary colonizer of coevolved hosts, drought stress decreased the resistance of Manchurian ash, but had no effect on constitutive bark phenolics, suggesting that they do not contribute to increased susceptibility in response to drought stress. The induced resistance of North American species to EAB in response to the exogenous application of methyl jasmonate was associated with increased bark concentrations of verbascoside, lignin and/or trypsin inhibitors, which decreased larval survival and/or growth in bioassays. This finding suggests that these inherently susceptible species possess latent defenses that are not induced naturally by larval colonization, perhaps because they fail to recognize larval cues or respond quickly enough. Finally, we propose future research directions that would address some critical knowledge gaps.

Global Transcriptome Analysis of the Tentacle of the Jellyfish Cyanea capillata Using Deep Sequencing and Expressed Sequence Tags: Insight into the Toxin- and Degenerative Disease-Related Transcripts

BACKGROUND

Jellyfish contain diverse toxins and other bioactive components. However, large-scale identification of novel toxins and bioactive components from jellyfish has been hampered by the low efficiency of traditional isolation and purification methods.

RESULTS

We performed de novo transcriptome sequencing of the tentacle tissue of the jellyfish Cyanea capillata. A total of 51,304,108 reads were obtained and assembled into 50,536 unigenes. Of these, 21,357 unigenes had homologues in public databases, but the remaining unigenes had no significant matches due to the limited sequence information available and species-specific novel sequences. Functional annotation of the unigenes also revealed general gene expression profile characteristics in the tentacle of C. capillata. A primary goal of this study was to identify putative toxin transcripts. As expected, we screened many transcripts encoding proteins similar to several well-known toxin families including phospholipases, metalloproteases, serine proteases and serine protease inhibitors. In addition, some transcripts also resembled molecules with potential toxic activities, including cnidarian CfTX-like toxins with hemolytic activity, plancitoxin-1, venom toxin-like peptide-6, histamine-releasing factor, neprilysin, dipeptidyl peptidase 4, vascular endothelial growth factor A, angiotensin-converting enzyme-like and endothelin-converting enzyme 1-like proteins. Most of these molecules have not been previously reported in jellyfish. Interestingly, we also characterized a number of transcripts with similarities to proteins relevant to several degenerative diseases, including Huntington's, Alzheimer's and Parkinson's diseases. This is the first description of degenerative disease-associated genes in jellyfish.

CONCLUSION

We obtained a well-categorized and annotated transcriptome of C. capillata tentacle that will be an important and valuable resource for further understanding of jellyfish at the molecular level and information on the underlying molecular mechanisms of jellyfish stinging. The findings of this study may also be used in comparative studies of gene expression profiling among different jellyfish species.

Sweet potato cysteine proteases SPAE and SPCP2 participate in sporamin degradation during storage root sprouting

Sweet potato sporamins are trypsin inhibitors and exhibit strong resistance to digestion by pepsin, trypsin and chymotrypsin. In addition, they constitute the major storage proteins in the sweet potato and, after degradation, provide nitrogen as a nutrient for seedling regrowth in sprouting storage roots. In this report, four cysteine proteases-one asparaginyl endopeptidase (SPAE), two papain-like cysteine proteases (SPCP1 and SPCP2), and one granulin-containing cysteine protease (SPCP3)-were studied to determine their association with sporamin degradation in sprouting storage roots. Sporamin degradation became significant in the flesh of storage roots starting from week 4 after sprouting and this correlated with expression levels of SPAE and SPCP2, but not of SPCP1 and SPCP3. In the outer flesh near the skin, sporamin degradation was more evident and occurred earlier than in the inner flesh of storage roots. Degradation of sporamins in the outer flesh was inversely correlated with the distance of the storage root from the sprout. Exogenous application of SPAE and SPCP2, but not SPCP3, fusion proteins to crude extracts of the outer flesh (i.e., extracted from a depth of 0.3cm and within 2cm of one-week-old sprouts) promoted in vitro sporamin degradation in a dose-dependent manner. Pre-treatment of SPAE and SPCP2 fusion proteins at 95°C for 5min prior to their application to the crude extracts reduced sporamin degradation. These data show that sweet potato asparaginyl endopeptidase SPAE and papain-like cysteine protease SPCP2 participate in sporamin degradation during storage root sprouting.

Effects of infrared treatment on urease, trypsin inhibitor and lipoxygenase activities of soybean samples

In this study, infrared (IR) treatment at different powers (814W, 1003W, 1208W, 1342W) and times (10min, 15min) were applied to unsoaked and soaked (30min, 45min) soybeans (cvs. Adasoy, Nazlican). Effects of IR treatment on urease, trypsin inhibitor, lipoxygenase-1 and lipoxygenase-3 activities were investigated. Infrared treatment caused a substantial reduction in urease and trypsin inhibitor activities and considerable decrease was observed as the IR power increased. Urease inactivation in unsoaked samples was achieved at even lower power (1208W). In contrast to urease activity, IR treatment had a more pronounced effect on trypsin inhibitor and lipoxygenase activities of soaked soybeans as compared to unsoaked counterparts. Maximum trypsin inhibitor reduction in IR-treated samples was 95% for cv. Adasoy and 97% for cv. Nazlican. IR power of 1003W was sufficient for complete inactivation of lipoxygenase-1 and lipoxygenase-3, regardless of the moisture contents of the samples.

Trypsin inhibitor from tamarindus indica L. seeds reduces weight gain and food consumption and increases plasmatic cholecystokinin levels

OBJECTIVES

Seeds are excellent sources of proteinase inhibitors, some of which may have satietogenic and slimming actions. We evaluated the effect of a trypsin inhibitor from Tamarindus indica L. seeds on weight gain, food consumption and cholecystokinin levels in Wistar rats.

METHODS

A trypsin inhibitor from Tamarindus was isolated using ammonium sulfate (30-60%) following precipitation with acetone and was further isolated with Trypsin-Sepharose affinity chromatography. Analyses were conducted to assess the in vivo digestibility, food intake, body weight evolution and cholecystokinin levels in Wistar rats. Histological analyses of organs and biochemical analyses of sera were performed.

RESULTS

The trypsin inhibitor from Tamarindus reduced food consumption, thereby reducing weight gain. The in vivo true digestibility was not significantly different between the control and Tamarindus trypsin inhibitor-treated groups. The trypsin inhibitor from Tamarindus did not cause alterations in biochemical parameters or liver, stomach, intestine or pancreas histology. Rats treated with the trypsin inhibitor showed significantly elevated cholecystokinin levels compared with animals receiving casein or water.

CONCLUSION

The results indicate that the isolated trypsin inhibitor from Tamarindus reduces weight gain by reducing food consumption, an effect that may be mediated by increased cholecystokinin. Thus, the potential use of this trypsin inhibitor in obesity prevention and/or treatment should be evaluated.

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea

BACKGROUND

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival.

RESULTS

Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects.

CONCLUSION

JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut.

Defense response in non-genomic model species: methyl jasmonate exposure reveals the passion fruit leaves' ability to assemble a cocktail of functionally diversified Kunitz-type trypsin inhibitors and recruit two of them against papain

Multiplicity of protease inhibitors induced by predators may increase the understanding of a plant's intelligent behavior toward environmental challenges. Information about defense mechanisms of non-genomic model plant passion fruit (Passiflora edulis Sims) in response to predator attack is still limited. Here, via biochemical approaches, we showed its flexibility to build-up a broad repertoire of potent Kunitz-type trypsin inhibitors (KTIs) in response to methyl jasmonate. Seven inhibitors (20-25 kDa) were purified from exposed leaves by chromatographic techniques. Interestingly, the KTIs possessed truncated Kunitz motif in their N-terminus and some of them also presented non-consensus residues. Gelatin-Native-PAGE established multiple isoforms for each inhibitor. Significant differences regarding inhibitors' activity toward trypsin and chymotrypsin were observed, indicating functional polymorphism. Despite its rarity, two of them also inhibited papain, and such bifunctionality suggests a recruiting process onto another mechanistic class of target protease (cysteine-type). All inhibitors acted strongly on midgut proteases from sugarcane borer, Diatraea saccharalis (a lepidopteran insect) while in vivo assays supported their insecticide properties. Moreover, the bifunctional inhibitors displayed activity toward midgut proteases from cowpea weevil, Callosobruchus maculatus (a coleopteran insect). Unexpectedly, all inhibitors were highly effective against midgut proteases from Aedes aegypti a dipteran insect (vector of neglected tropical diseases) opening new avenues for plant-derived PIs for vector control-oriented research. Our results reflect the KTIs' complexities in passion fruit which could be wisely exploited by influencing plant defense conditions. Therefore, the potential of passion fruit as source of bioactive compounds with diversified biotechnological application was strengthened.

Genomic and cDNA Cloning, Characterization ofDelonix regiaTrypsin Inhibitor (DrTI) Gene, and Expression of DrTI inEscherichia coli

Degenerate primers were designed based on all possible sequences of the N-terminal and C-terminal regions of Delonix regia trypsin inhibitor (DrTI). Five hundred sixty-one bp of polymerase chain reaction (PCR) product was amplified using the above degenerate primers and genomic DNA and cDNA of Delonix regia as a template. The amplified PCR products were cloned and sequenced. DNA sequence analysis of cDNA and genomic clones of DrTI have the same nucleotide sequence in the coding region, and manifested a genomic clone without intervening sequences in the coding region. The amino acid sequence deduced from the DrTI genomic and cDNA clones agreed with that identified via amino acid sequencing analysis, except that two amino acid residues, Ser and Lys, existed between residues Lys141 and Ser142. DrTI open reading frame was then amplified and cloned in-frame with GST in pGEX4T-1 and overexpressed in Escherichia coli to yield a glutathione S-transferase (GST)-fusion protein with a calculated molecular mass of about 45 kDa. The recombinant DrTI (reDrTI) was derived by treating the GST-DrTI fusion protein with thrombin. Both the reDrTI and GST-DrTI fusion protein exhibited a strong identical inhibitory effect on trypsin activity.