Characterization and cytotoxic activity of apoptosis-inducing pierisin-5 protein from white cabbage butterfly

General ADP-Ribosylation Mechanism Based on the Structure of ADP-Ribosyltransferase-Substrate Complexes

ADP-ribosylation is a ubiquitous modification of proteins and other targets, such as nucleic acids, that regulates various cellular functions in all kingdoms of life. Furthermore, these ADP-ribosyltransferases (ARTs) modify a variety of substrates and atoms. It has been almost 60 years since ADP-ribosylation was discovered. Various ART structures have been revealed with cofactors (NAD+ or NAD+ analog). However, we still do not know the molecular mechanisms of ART. It needs to be better understood how ART specifies the target amino acids or bases. For this purpose, more information is needed about the tripartite complex structures of ART, the cofactors, and the substrates. The tripartite complex is essential to understand the mechanism of ADP-ribosyltransferase. This review updates the general ADP-ribosylation mechanism based on ART tripartite complex structures.

Glycosaminoglycan lyase: A new competition between bacteria and the pacific white shrimp Litopenaeus vannamei

Horizontal gene transfer (HGT) is an important evolutionary force in the formation of prokaryotic and eukaryotic genomes. In recent years, many HGT genes horizontally transferred from prokaryotes to eukaryotes have been reported, and most of them are present in arthropods. The Pacific white shrimp Litopenaeus vannamei, an important economic species of arthropod, has close relationships with bacteria, providing a platform for horizontal gene transfer (HGT). In this study, we analyzed bacteria-derived HGT based on a high-quality genome of L. vannamei via a homology search and phylogenetic analysis, and six HGT genes were identified. Among these six horizontally transferred genes, we found one gene (LOC113799989) that contains a bacterial chondroitinase AC structural domain and encodes an unknown glycosaminoglycan (GAG) lyase in L. vannamei. The real-time quantitative PCR results showed that the mRNA expression level of LOC113799989 was highest in the hepatopancreas and heart, and after stimulation by Vibrio parahaemolyticus, its mRNA expression level was rapidly up-regulated within 12 h. Furthermore, after injecting si-RNA and stimulation by V. parahaemolyticus, we found that the experimental group had a higher cumulative mortality rate in 48 h than the control group, indicating that the bacteria-derived GAG lyase can reduce the mortality of shrimp with respect to infection by V. parahaemolyticus and might be related to the resistance of shrimp to bacterial diseases. Our findings contribute to the study of the function of GAGs and provide new insights into GAG-related microbial pathogenesis and host defense mechanisms in arthropods.

Pierisin, Cytotoxic and Apoptosis-Inducing DNA ADP-Ribosylating Protein in Cabbage Butterfly

Pierisin-1 was serendipitously discovered as a strong cytotoxic and apoptosis-inducing protein from pupae of the cabbage butterfly Pieris rapae against cancer cell lines. This 98-kDa protein consists of the N-terminal region (27 kDa) and C-terminal region (71 kDa), and analysis of their biological function revealed that pierisin-1 binds to cell surface glycosphingolipids on the C-terminal side, is taken up into the cell, and is cleaved to N- and C-terminal portions, where the N-terminal portion mono-ADP-ribosylates the guanine base of DNA in the presence of NAD to induce cellular genetic mutation and apoptosis. Unlike other ADP-ribosyltransferases, pieisin-1 was first found to exhibit DNA mono-ADP-ribosylating activity and show anti-cancer activity in vitro and in vivo against various cancer cell lines. Pierisin-1 was most abundantly produced during the transition from the final larval stage to the pupal stage of the cabbage butterfly, and this production was regulated by ecdysteroid hormones. This suggests that pierisn-1 might play a pivotal role in the process of metamorphosis. Moreover, pierisin-1 could contribute as a defense factor against parasitization and microbial infections in the cabbage butterfly. Pierisin-like proteins in butterflies were shown to be present not only among the subtribe Pierina but also among the subtribes Aporiina and Appiadina, and pierisin-2, -3, and -4 were identified in these butterflies. Furthermore, DNA ADP-ribosylating activities were found in six different edible clams. Understanding of the biological nature of pierisin-1 with DNA mono-ADP-ribosylating activity could open up exciting avenues for research and potential therapeutic applications, making it a subject of great interest in the field of molecular biology and biotechnology.

Molecular dynamics simulation, synthesis and topoisomerase inhibitory actions of vanillin derivatives: a systematic computational structural integument

A series of 4-hydroxy-3-methoxy benzaldehyde (vanillin) derivatives (3a-3r) was designed for the principle of Schiff base condensation with several individual sulfanilamide analogues. The inhibitory potencies of the designed compounds were evaluated through molecular docking simulation studies against the targets, breast cancer-topo isomerase-IIα and estrogen receptor-α; and the top scoring poses with higher binding energy were selected to assess the mode of binding and stability of each complex through molecular dynamics simulations. Compounds that remained stable in the active sites of the both target receptors through a number of strong H-bonds and hydrophobic contacts were selected. Based on the computational results, these selected compounds, 3b, 3e and 3f were synthesized and were followed up for structural elucidation attempts, by FT/ATR, ¹H NMR and ¹³C NMR. From the experimental in vitro studies on 3b, 3e and 3f, the following remarkable activities against breast cancer cell line were done; IC₅₀ values of 3b, 3e and 3f were noted, 6.7, 4.3 and 11 ng/mL, respectively. These newly synthesized compounds may be used as novel inhibitors of nuclear receptors with potential therapeutic applications in control of cancer.Communicated by Ramaswamy H. Sarma.

Influence of Padina gymnospora on Apoptotic Proteins of Oral Cancer Cells-a Proteome-Wide Analysis

Oral carcinoma is one of the most vicious forms of cancer with a very low survival rate, as its patients often respond poorly to conventional chemotherapy. Presently several researchers are attempting to pursue an alternative to this therapy using natural products. Considering the promising strategy and induction of apoptosis to target the cancer cells, we evaluated the influence of a seaweed Padina gymnospora (15 µg/ml and 20 µg/ml) in enhancing apoptosis of oral cancer cells (KB-CHR-8-5) after 24-h incubation. The morphological changes indicating apoptosis were primarily assessed using a light microscope after which the apoptosis was confirmed by performing AO/EB staining method. Subsequently, MMP and ROS levels in the cells were assessed using Rh 123 and DCFH-DA staining procedures, respectively. All the above tests confirmed the ability of P. gymnospora to accelerate apoptosis in the oral cancer cells. As a next step, wide proteome analysis was performed where the proteins from P. gymnospora-treated cells were separated using the 2D electrophoresis technique and compared with that of control cells to isolate the differentially expressed proteins. This procedure resulted in the isolation of 10 proteins which were identified using MALDI-TOF/TOF MS, which established that most of the isolated proteins were part of the apoptotic process of the cell. The proteins identified are part of huge and complex pathways where it gets linked with many more genes which are also associated with apoptosis. Bioinformatics of these identified proteins was analyzed using STRING and PANTHER databases. These proteins contribute to cell apoptosis by affecting various functions, biological processes, and the synthesis of cellular components. PANTHER also demonstrated that these proteins belong to the classes of proteins that take part in several vital pathways of the cell among which the apoptotic pathway is the predominant one.

Synthesis, Characterization, and Antimicrobial and Antiproliferative Effects of CuO-TiO2-Chitosan-Escin Nanocomposites on Human Leukemic MOLT4 Cells

Nanocomposites comprised of CuO-TiO2-chitosan-escin, which has adjustable physicochemical properties, provide a solution for therapeutic selectivity in cancer treatment. By controlling the intrinsic signaling primarily through the mitochondrial signaling pathway, we desired nanocomposites with enhanced anticancer activity by containing CuO-TiO2-chitosan-escin. The metal oxides CuO and TiO2, the natural polymer chitosan, and a phytochemical compound escin were combined to form CuO-TiO2-chitosan-escin nanocomposites. The synthesized nanocomposites were confirmed and characterized using FTIR spectroscopy, TEM, and UV-Vis absorption spectroscopy. A human leukemia cell line (MOLT-4) was used to assess the efficacy and selectivity of nanocomposites. Based on a cytotoxicity study, CuO-TiO2-chitosan-escin nanocomposites had inhibition concentrations (IC50) of 13.68, 8.9, and 7.14 µg/mL against human T lymphoblast cells after 24, 48, and 72 h of incubation, respectively. Compared with untreated MOLT-4 cells, CuO-TiO2-chitosan-escin nanocomposite-treated cells significantly increased (p < 0.05) caspase-3, -8, and -9 and decreased the levels of antioxidant enzymes GR, SOD, and GSH. Furthermore, MDA for lipid peroxidase and ROS levels significantly increased (p < 0.05) in the treated cells than in the untreated cells. Remarkably, CuO-TiO2-chitosan-escin nanocomposite-mediated control of cell cycles were mainly achieved through the activation of caspase-3, -8, and -9.

Synthesis of Zinc Oxide (ZnO)-Titanium Dioxide (TiO2)-Chitosan-Farnesol Nanocomposites and Assessment of Their Anticancer Potential in Human Leukemic MOLT-4 Cell Line

Leukemia is the most prevalent cancer in children and one of the most common and deadly cancers that affect adults. Several metal oxide nanoparticles, biopolymers, and phytochemicals have been discovered to target cancer cells selectively while inflicting low to no damage to healthy cells. Among the existing nanoparticle synthesis methodologies, biologically synthesized nanoparticles using phytochemicals have emerged as a straightforward, economical, and environmentally sound strategy. The synergistic antitumor potential of ZnO-TiO2-chitosan-farnesol nanocomposites (NCs) against leukemia MOLT-4 cells was investigated in the current study. After synthesizing the NCs, characterization of the same was carried out using XRD, DLS, FESEM, TEM, PL, EDX, and FTIR spectroscopy. To analyze its anticancer activity, MOLT-4 cells were cultured and treated at diverse dosages of NCs. The cell viability upon treatment was examined by MTT assay. The morphological and nuclear modifications were observed by dual staining. ROS and MMP levels were observed by DCFH-DA staining and Rh-123 dye, respectively. Furthermore, the caspase 3, 8, and 9 levels were examined by performing ELISA. The XRD patterns exhibited a hexagonal structure of the NCs. In the DLS spectrum, the hydrodynamic diameter of the NCs was observed to be 126.2 nm. The electrostatic interface between the ZnO-TiO2-chitosan-farnesol NCs was confirmed by the FTIR spectra. A significant loss of cell viability in a dosage-dependent trend confirmed the cytotoxic effect of the NCs. An elevated ROS level and MMP depletion suggested apoptosis-associated cell death via the intrinsic pathway, which was confirmed by elevated expressions of caspase 3, 8, and 9 markers. Thus, the results showed that the synthesized NCs demonstrated a remarkable anticancer potential against leukemic cells and can be potentially valuable in cancer treatments. The findings from this study conclude that this is a new approach for modifying the physicochemical characteristics of ZnO-TiO2-chitosan-farnesol composites to increase their properties and synergistically exhibit anticancer properties in human leukemic cancer cells.

CuO-TiO2-Chitosan-Berbamine Nanocomposites Induce Apoptosis through the Mitochondrial Pathway with the Expression of P53, BAX, and BCL-2 in the Human K562 Cancer Cell Line

In this study, cells from human Chronic Myelogenous Leukemia (K562) were cultivated with CuO-TiO2-Chitosan-Berbamine nanocomposites. We examined nanocomposites using XRD, DLS, FESEM, TEM, PL, EDAX, and FTIR spectroscopy, as well as MTT for cytotoxicity, and AO/EtBr for apoptotic morphology assessment. The rate of apoptosis and cell cycle arrests was determined using flow cytometry. Flow cytometry was also employed to identify pro- and antiapoptotic proteins such as Bcl2, Bad, Bax, P53, and Cyt C. The FTIR spectrum revealed that the CuO-TiO2-Chitosan-Berbamine nanocomposites were electrostatically interlocked. The nanocomposites' XRD signals revealed a hexagonal shape. In the DLS spectrum, nanocomposites were found to have a hydrodynamic diameter. As a result of their cytotoxic action, nanocomposites displayed concentration-dependent cytotoxicity. The nanocomposites, like Doxorubicin, caused cell cycle phase arrest in K562 cells. After treatment with IC50 concentrations of CuO-TiO2-Chitosan-Berbamine nanocomposites and Doxorubicin, a substantial percentage of cells were in G2/M stage arrest. Caspase-3, -7, -8, -9, Bax, Bad, Cyt C, and P53 expression were considerably enhanced in K562 cells, whereas Bcl2 expression was decreased, indicating that these cells may have therapeutic potential against human blood cancer/leukemia-derived disorders. As a result, the nanocomposites demonstrated outstanding anticancer potential against leukemic cells. CuO-TiO2-Chitosan-Berbamine, according to our findings.

In vitro DNA binding activity and molecular docking reveals pierisin-5 as an anti-proliferative agent against gastric cancer

Pierisin-5 is a DNA dependent ADP ribosyltransferase (ADRT) protein from the larvae of Indian cabbage white butterfly, Pieris canidia. Interestingly, Pierisin-5 ADP-ribosylates the DNA as a substrate, but not the protein and subsequently persuades apoptotic cell death in human cancer cells. This has led to the investigation on the DNA binding activity of Pierisin-5 using in vitro and in silico approaches in the present study. However, both the structure and the mechanism of ADP-ribosylation of pierisin-5 are unknown. In silico modeled structure of the N-terminal ADRT catalytic domain interacted with the minor groove of B-DNA for ribosylation with the help of β-NAD⁺ which lead to a structural modification in DNA (DNA adduct). The possible interaction between calf thymus DNA (CT-DNA) and purified pierisin-5 protein was studied through spectral-spatial studies and the blue shift and hyperchromism in the UV-Visible spectra was observed. The DNA adduct property of pierisin-5 protein was validated by in vitro cytotoxic assay on human gastric (AGS) cancer cell lines. Our study is the first report of the mechanism of DNA binding property of pierisin-5 protein which leads to the induction of cytotoxicity and apoptotic cell death against cancer cell lines.Communicated by Ramaswamy H. Sarma.

Calpain inhibition improves erectile function in diabetic mice via upregulating endothelial nitric oxide synthase expression and reducing apoptosis

Calpain activation contributes to hyperglycemia-induced endothelial dysfunction and apoptosis. This study was designed to investigate the role of calpain inhibition in improving diabetic erectile dysfunction (ED) in mice. Thirty-eight-week-old male C57BL/6J mice were divided into three groups: (1) nondiabetic control group, (2) diabetic mice + vehicle group, and (3) diabetic mice + MDL28170 (an inhibitor of calpain) group. Type 1 diabetes was induced by intraperitoneal injection of streptozotocin at 60 mg kg⁻¹ body weight for 5 consecutive days. Thirteen weeks later, diabetic mice were treated with MDL28170 or vehicle for 4 weeks. The erectile function was assessed by electrical stimulation of the cavernous nerve. Penile tissues were collected for measurement of calpain activity and the endothelial nitric oxide synthase (eNOS)-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway. Terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick end labeling (TUNEL) staining was used to evaluate apoptosis. Caspase-3 expression and activity were also measured to determine apoptosis. Our results showed that erectile function was enhanced by MDL28170 treatment in diabetic mice compared with the vehicle diabetic group. No differences in calpain-1 and calpain-2 expressions were observed among the three groups. However, calpain activity was increased in the diabetic group and reduced by MDL28170. The eNOS-NO-cGMP pathway was upregulated by MDL28170 treatment in diabetic mice. Additionally, MDL28170 could attenuate apoptosis and increase the endothelium and smooth muscle levels in corpus cavernosum. Inhibition of calpain could improve erectile function, probably by upregulating the eNOS-NO-cGMP pathway and reducing apoptosis.

Induction of Apoptosis by Pierisin-6 in HPV Positive HeLa and HepG2 Cancer Cells is Mediated by the Caspase-3 Dependent Mitochondrial Pathway

Background:

To explore the cytotoxic and apoptotic activity of the pierisin-6 protein in HPV HeLa and HepG2 cell lines.

Methods:

In this study, isolation, and purification of cytotoxic Prierisin-6 from the larvae of Pieris napi by affinity column chromatography techniques. Characterization of full-length mRNA of pierisin-6 gene was performed using 3’/5’ RACE PCR. The quantitative RT-PCR used to study the developmental stage-specific expression of pierisin-6 mRNA. The most effective concentration of Pierisin-6 protein was determined by measuring cell proliferation. Apoptosis was assessed using AO/Et-Br, Propidium Iodide, and Rhodamine 123 assays, whereas protein levels of caspase 3, cytochrome C were evaluated by ELISA method. Pierisin-6 induced cell cycle arrest was determined using Propidium iodide by FACS.

Results:

In this study, Pierisin-6, a novel apoptotic protein was found to have cytotoxicity against HeLa, HepG2 human cancer cell lines and L-132 human lung epithelial cell line. Among the target cells, HeLa was the most sensitive to Pierisin-6. Flow cytometry analysis confirms an increased percentage of apoptotic cells in sub G1 phase and cell cycle arrest at S phase. Alteration in the transmembrane potential of mitochondria, Cytochrome c released from the mitochondrial membrane, and caspase substrate assay demonstrated the cleavage of Ac- DEVD-pNA signifying the activation of Caspase-3. These findings suggested that Pierisin-6 significantly induce apoptosis in HeLa and HepG2 cells and is attributed mainly through a mitochondrial pathway by activation of caspases. The developmental and stage-specific expression of pierisin-6 mRNA was one thousand-fold increased from second to third instar larvae and gradually declined before pupation.

Conclusion:

Pierisin-6 represents a promising therapeutic approach for liver cancer patients.

A vital ubiquitin-conjugating enzyme CgUbe2g1 participated in regulation of immune response of Pacific oyster Crassostrea gigas

As an important post-translational protein modification, ubiquitination has been demonstrated to play a vital role in immune response of vertebrates. Ubiquitin (Ub)-conjugating enzyme E2 is the "heart" of ubiquitination, which is responsible for Ub cellular signaling and substrate modification. In the present study, an Ub-conjugating enzyme E2 (designed as CgUbe2g1) was identified from oyster Crassostrea gigas, and its regulation in the immune response against lipopolysaccharide (LPS) stimulation was investigated. CgUbe2g1 encoded a polypeptide of 168 amino acids with the predicted molecular mass of 19.20 kDa and contained conserved catalytic 'Ubc' domains. It shared a higher similarity with the known UBC2G1 type E2s and was closely clustered with the type E2s identified from invertebrates in the phylogenetic assay. The mRNA transcripts of CgUbe2g1 were mainly distributed in hemocyte, mantle, hepatopancreas and male gonad of C. gigas. CgUbe2g1 protein was found to be colocalized with Ub around the nucleus of oyster hemocyte. The recombinant CgUbe2g1 protein (rCgUbe2g1) could activate the ubiquitination in vitro by binding both activated and un-activated Ub. The expressions of inflammation-related factors TNF-α and NF-κB in CgUbe2g1 transfected cells were both significantly up-regulated after LPS stimulation, which were 12.9-fold at 3 h (p < 0.01) and 2.3-fold at 6 h (p < 0.01) of that in negative control group, respectively. The phagocytic rate of hemocyte and the ROS level in hemocyte were both significantly decreased (p < 0.01), while the apoptosis rate was significantly increased (p < 0.01) after CgUbe2g1 mRNA was interfered. These results demonstrated that Ub-conjugating enzyme CgUbe2g1 was involved in the innate immune response of oyster against invading pathogen, which might play important roles in the activation of inflammatory response and regulation of cellular immune response.

Construction and biological evaluation of different self-assembled nanoarchitectures of FZU-03,010

Chemotherapy is currently one of the promising therapeutic methods for non-small-cell lung cancer (NSCLC), but the emergence of multidrug resistance (MDR) is the greatest obstacle to efficient drug delivery for successful chemotherapy. Nanotechnology-based drug delivery holds great promise to promote intracellular drug delivery to reverse MDR. In this work, we used our previously synthesized ursolic acid (UA) derivative, FZU-03,010 (F3), to prepare nanodrugs of F3 with different architectures and study the role of the structure on the physiochemical properties and the biological effects against A549 and its PTX-resistant A549/PTX lung cancer cells. Using different preparation methods, amphiphilic F3 could self-assemble into different structures such as nanoaggregates (F3-NA), vesicles (F3-VC), or nanoparticles (F3-NP) with different physiochemical properties. The self-assembled nanodrugs could be utilized for the entrapment of fluorophores and showed different cellular uptake efficiencies. The cytotoxicity results demonstrated that compared with UA, F3-NA and F3-NP could suppress A549 and A549/PTX cells viability more potently at lower concentration. In addition, F3-NA and F3-NP could induce G1 cell cycle arrest, cell apoptosis and caspase-3 activation more efficiently than that of UA. Furthermore, F3-NA and F3-NP could effectively inhibit PI3K/Akt pathway and decrease the expression of Bcl-2 and the cell cycle-dependent kinase inhibitors p-ERK1/2 and Cyclin D1 in both A549 and A549/PTX cells. In conclusion, our results suggest that the UA derivative F3 is more potent in inhibiting cancer cell proliferation, and F3-NA and F3-NP have the potential to be developed as a therapeutic agent for resistant NSCLC cells.

Pharmacological potential of Bidens pilosa L. and determination of bioactive compounds using UHPLC-QqQLIT-MS/MS and GC/MS

Background

Research of natural products from traditionally used medicinal plants to fight against the human ailments is fetching attention of researchers worldwide. Bidens pilosa Linn. var. Radiata (Asteraceae) is well known for its folkloric medicinal use against various diseases from many decades. Mizoram, North East India, has high plant diversity and the use of this plant as herbal medicine is deep rooted in the local tribes. The present study was executed to understand the pharmacological potential of B. pilosa leaves extract.

Methods

The antimicrobial potential was determined using agar well diffusion and broth microdilution method against bacterial and yeast pathogens. Cytotoxicity was evaluated using MTT and apoptotic DNA fragmentation assays. Further, the antioxidant ability of the extract was analysed using DPPH and ABTS free radical scavenging assay. Mosquitocidal activity was evaluated against third in-star larvae of C. quinquefasciatus using dose response and time response larvicidal bioassay. Additionally, the major phenolic and volatile compounds were determined using UHPLC-QqQ_LIT-MS/MS and GC/MS respectively.

Results

We found that the extract showed highest antimicrobial activity against E. coli (MIC 80 μg/mL and IC₅₀ 110.04 μg/mL) and showed significant cytotoxicity against human epidermoid carcinoma (KB-3-1) cells with IC₅₀ values of 99.56 μg/mL among the tested cancer cell lines.

The IC₅₀ values for scavenging DPPH and ABTS was 80.45 μg/mL and 171.6 μg/mL respectively. The extract also showed the high phenolics (72 μg GAE/mg extract) and flavonoids (123.3 μg Quercetin /mg extract). Lastly, five bioactive and six volatile compounds were detected using UHPLC-QqQ_LIT-MS/MS and GC-MS respectively which may be responsible for the plant’s bioactivities. An anticancerous compound, Paclitaxel was detected and quantified for the first time from B. pilosa leaves extract, which further showed the anticancerous potential of the tested extract.

Conclusion

On the basis of the present investigation, we propose that the leaf extract of B. pilosa might be a good candidate for the search of efficient environment friendly natural bioactive agent and pharmaceutically important compounds.

Structural basis of autoinhibition and activation of the DNA-targeting ADP-ribosyltransferase pierisin-1

ADP-ribosyltransferases transfer the ADP-ribose moiety of βNAD⁺ to an acceptor molecule, usually a protein that modulates the function of the acceptor. Pierisin-1 is an ADP-ribosyltransferase from the cabbage butterfly Pieris rapae and is composed of N-terminal catalytic and C-terminal ricin B-like domains. Curiously, it ADP-ribosylates the DNA duplex, resulting in apoptosis of various cancer cells, which has raised interest in pierisin-1 as an anti-cancer agent. However, both the structure and the mechanism of DNA ADP-ribosylation are unclear. Here, we report the crystal structures of the N-terminal catalytic domain of pierisin-1, its complex with βNAD⁺, and the catalytic domain with the linker connecting it to the ricin B-like domains. We found that the catalytic domain possesses a defined, positively charged region on the molecular surface but that its overall structure is otherwise similar to those of protein-targeting ADP-ribosyltransferases. Electrophoretic mobility shift assays and site-directed mutagenesis indicated that pierisin-1 binds double-stranded but not single-stranded DNA and that Lys¹²², Lys¹²³, and Lys¹²⁴, which are found in a loop, and Arg¹⁸¹ and Arg¹⁸⁷, located in a basic cleft near the loop, are required for DNA binding. Furthermore, the structure of the catalytic domain with the linker revealed an autoinhibitory mechanism in which the linker occupies and blocks both the βNAD⁺- and DNA-binding sites, suggesting that proteolytic cleavage to remove the linker is necessary for enzyme catalysis. Our study provides a structural basis for the DNA-acceptor specificity of pierisin-1 and reveals that a self-regulatory mechanism is required for its activity.

Complete genome of Pieris rapae, a resilient alien, a cabbage pest, and a source of anti-cancer proteins

The Small Cabbage White ( Pieris rapae) is originally a Eurasian butterfly. Being accidentally introduced into North America, Australia, and New Zealand a century or more ago, it spread throughout the continents and rapidly established as one of the most abundant butterfly species. Although it is a serious pest of cabbage and other mustard family plants with its caterpillars reducing crops to stems, it is also a source of pierisin, a protein unique to the Whites that shows cytotoxicity to cancer cells. To better understand the unusual biology of this omnipresent agriculturally and medically important butterfly, we sequenced and annotated the complete genome from USA specimens. At 246 Mbp, it is among the smallest Lepidoptera genomes reported to date. While 1.5% positions in the genome are heterozygous, they are distributed highly non-randomly along the scaffolds, and nearly 20% of longer than 1000 base-pair segments are SNP-free (median length: 38000 bp). Computational simulations of population evolutionary history suggest that American populations started from a very small number of introduced individuals, possibly a single fertilized female, which is in agreement with historical literature. Comparison to other Lepidoptera genomes reveals several unique families of proteins that may contribute to the unusual resilience of Pieris. The nitrile-specifier proteins divert the plant defense chemicals to non-toxic products. The apoptosis-inducing pierisins could offer a defense mechanism against parasitic wasps. While only two pierisins from Pieris rapae were characterized before, the genome sequence revealed eight, offering additional candidates as anti-cancer drugs. The reference genome we obtained lays the foundation for future studies of the Cabbage White and other Pieridae species.