Cytolytic Peptides Research Articles

A Molecular Dynamics Study of the Short-Helical-Cytolytic Peptide Assembling and Bioactive on Membrane Interface

Cytolytic peptides (CPs) have long been employed as broad-spectrum antibiotic agents to overcome multidrug resistance. However, the development of novel peptide drugs is still limited by the elusive molecular understanding of the membrane-lysis mechanism and modeling of CPs, especially of the short helical species. In this study, a known anticancer CP named PTP-7b (FLGALFKALSHLL) in disrupting membranes via self-assembling approach was studied by combining experiments and time-extended coarse-grained dynamic simulations. Effective membrane disintegration was induced by aggregation of the membrane-bound peptide individuals, rather than the preassembled peptide clusters. The disturbance level of lipid bilayers depended on the peptide concentrations, which was responsible for the long time-costing of PTP-7b in killing cells. On the basis of lines of simulations and energy-landscape calculations, the dynamics of membrane deformation evolving toward preliminary leakage resulted from the aggregated PTP-7b was d...

The development of activatable lytic peptides for targeting triple negative breast cancer

Cytolytic peptides are an emerging class of promising cancer therapeutics shown to overcome drug resistance. They eliminate cancer cells via disruption of the phospholipid bilayer of cell membranes, a mechanism that differentiates it from traditional treatments. However, applications of lytic peptides via systematic administration are hampered by nonspecific toxicity. Here, we describe activatable, masked lytic peptides that are conjugated with anionic peptides via a cleavable linker sensitive to matrix metalloproteinases (Ac-w-βA-e8-XPLG*LAG-klUklUkklUklUk-NH2; lower case letters in the sequences represent D-amino-acids, U=Aib, α-aminoisobutyric acid, *cleavage site). The peptides were activated upon being introduced into the triple negative breast cancer cell line MDA-MB-231, which overexpresses secreted matrix metalloproteinases, to selectively cleave the peptide linker. Our results indicate that the activatable design could be applied to improve the targeting ability of lytic peptides.

Identification and molecular cloning of novel antimicrobial peptides from skin secretions of the Chinese bamboo leaf odorous frog (Odorrana versabilis) and the North American pickerel frog (Rana palustris)

ObjectiveAmphibian skin secretions are an abundant source of bioactive peptides, some of which could be developed as candidate drugs. Among these natural peptides, cytolytic peptides have attracted the most attention given that they might replace conventional antibiotics and help deal with the problem of microbial resistance. This study discovered two bioactive peptides, Brevinin-1-PLr and Nigrocin-2-OV, from two species frogs, the Chinese bamboo leaf odorous frog (Odorrana versabilis) and the North American pickerel frog (Rana palustris), respectively. Their antimicrobial, anticancer and hemolytic activities were also investigated. MethodscDNA sequences encoding peptides were cloned from cDNA libraries constructed from the lyophilized secretions of the Chinese bamboo leaf odorous frog and the North American pickerel frog. By reversed-phase HPLC and MS/MS fragmentation sequencing, the encoded novel peptides, named Nigrocin-2-OV and Brevinin-1-PLr, were identified in skin secretions and their structures were confirmed. Replicates of both peptides were produced through solid phase peptide synthesis. Their antimicrobial and anticancer activity was studied against three types of microorganisms (Staphylococcus aureus, Candida albicans, and Escherichia coli) and five cancer cell lines (NCI-H157, PC-3, MDA-MB-435s, MCF-7, and U251MG). Their hemolytic activity was investigated using whole horse blood. ResultsIn this research, cDNA sequences encoding two novel 24-mer peptides were cloned from cDNA libraries constructed from the lyophilized skin secretions of the Chinese bamboo leaf odorous frog and the North American pickerel frog. Both of the peptides had the strongest inhibitory effect against C. albicans, and IC50 values against five cancer cell lines were all under 6 μM. ConclusionsNigrocin-2-OV and Brevinin-1-PLr had the strong ability to inhibit the proliferation of studied microorganisms and tumor cell lines, with slight hemolytic activity. Compared with Brevinin-1-PLr, Nigrocin-2-OV exhibited higher antimicrobial and anticancer activity but slightly higher hemolytic activity.

Biodegradable nanoparticles loaded with tetrameric melittin: preparation and membrane disruption evaluation.

Melittin is the main component of bee venom consisting of 26 amino acids that has multiple effects, including antibacterial, antiviral and anti-inflammatory in various cell types. This peptide forms pores in biological membranes and triggers cell death. Therefore it has potential as an anti-cancer therapy. However, the therapeutic application of melittin is limited due to its main side effect, hemolysis, which is especially pronounced following intravenous administration. In the present study, we formulated tetrameric melittin-carrying poly-D,L-lactic-co-glycolic acid nanoparticles (PLGA-NPs) and analyzed the lytic activity of this system on liposomes that resembles breast cancer cells. Tetrameric melittin binds avidly to PLGA-NPs with an encapsulation efficiency of 97% and retains its lytic activity demonstrating the effectiveness of PLGA-NPs as nanocarriers for this cytolytic peptide.

Lifting the veil on fungal toxins.

Lifting the veil on fungal toxins.

Lipid-Bilayer Dynamics Probed by a Carbon Dot-Phospholipid Conjugate

Elucidating the dynamic properties of membranes is important for understanding fundamental cellular processes and for shedding light on the interactions of proteins, drugs, and viruses with the cell surface. Dynamic studies of lipid bilayers have been constrained, however, by the relatively small number of pertinent molecular probes and the limited physicochemical properties of the probes. We show that a lipid conjugate comprised of a fluorescent carbon dot (C-dot) covalently attached to a phospholipid constitutes a versatile and effective vehicle for studying bilayer dynamics. The C-dot-modified phospholipids readily incorporated within biomimetic membranes, including solid-supported bilayers and small and giant vesicles, and inserted into actual cellular membranes. We employed the C-dot-phospholipid probe to elucidate the effects of polymyxin-B (a cytolytic peptide), valproic acid (a lipophilic drug), and amyloid-β (a peptide associated with Alzheimer’s disease) upon bilayer fluidity and lipid dynamics through the application of various biophysical techniques.

Peptide Toxins in Solitary Wasp Venoms.

Solitary wasps paralyze insects or spiders with stinging venom and feed the paralyzed preys to their larva. Accordingly, the venoms should contain a variety of constituents acting on nervous systems. However, only a few solitary wasp venoms have been chemically studied despite thousands of species inhabiting the planet. We have surveyed bioactive substances in solitary wasp venoms found in Japan and discovered a variety of novel bioactive peptides. Pompilidotoxins (PMTXs), in the venoms of the pompilid wasps Anoplius samariensis and Batozonellus maculifrons, are small peptides consisting of 13 amino acids without a disulfide bond. PMTXs slowed Na+ channel inactivation, in particular against neuronal type Na+ channels, and were rather selective to the Nav1.6 channel. Mastoparan-like cytolytic and antimicrobial peptides are the major components of eumenine wasp venoms. They are rich in hydrophobic and basic amino acids, adopting a α-helical secondary structure, and showing mast cell degranulating, antimicrobial and hemolytic activities. The venom of the spider wasp Cyphononyx fulvognathus contained four bradykinin-related peptides. They are hyperalgesic and, dependent on the structure, differently associated with B1 or B2 receptors. Further survey led to the isolation of leucomyosuppressin-like FMRFamide peptides from the venoms of the digger wasps Sphex argentatus and Isodontia harmandi. These results of peptide toxins in solitary wasp venoms from our studies are summarized.

Candidalysin is a fungal peptide toxin critical for mucosal infection.

Cytolytic proteins and peptide toxins are classical virulence factors of several bacterial pathogens which disrupt epithelial barrier function, damage cells and activate or modulate host immune responses. Until now human pathogenic fungi were not known to possess such toxins. Here we identify the first fungal cytolytic peptide toxin in the opportunistic pathogen Candida albicans. This secreted toxin directly damages epithelial membranes, triggers a danger response signaling pathway and activates epithelial immunity. Toxin-mediated membrane permeabilization is enhanced by a positively charged C-terminus and triggers an inward current concomitant with calcium influx. C. albicans strains lacking this toxin do not activate or damage epithelial cells and are avirulent in animal models of mucosal infection. We propose the name ‘Candidalysin’ for this cytolytic peptide toxin; a newly identified, critical molecular determinant of epithelial damage and host recognition of the clinically important fungus, C. albicans.

Microbiology: Fungus produces a toxic surprise.

A protein fragment released by filaments of the fungus Candida albicans destroys host cells. This is the first demonstration that human fungal pathogens other than moulds can release toxic peptides. See Article p.64 This study identifies and characterizes a cytolytic peptide toxin in the opportunistic human fungal pathogen Candida albicans. The peptide, termed Candidalysin, acts both as a crucial virulence factor that permeabilizes the host cell plasma membrane and as a key signal that triggers a host danger-response pathway.

IRGD-targeted delivery of a pro-apoptotic peptide activated by cathepsin B inhibits tumor growth and metastasis in mice.

The use of cytolytic peptides with potential therapeutic properties is a promising approach to cancer therapy due to their convenient automated synthesis and their capacity for modifications. However, the use of cytolytic peptides is limited due to their nonspecific cytolytic activity. In this study, we designed a tumor-targeting proapoptotic system based on an amphipathic D-amino acid-modified apoptotic peptide, KLA, a variant of (KLAKLAK)2, which is fused with a linear tumor-penetrating homing peptide iRGD through specific cathepsin B (CTSB) cleavage sequences that are overexpressed in many types of tumor tissues. Our data show that the procytotoxic peptide D(KLAKLAKKLAKLA)K-GG-iRGD (m(KLA)-iRGD) is internalized into cultured tumor cells through a neuropilin-1 (NRP1)-activated pathway by iRGD delivery. Once inside the cells, the peptide triggers rapid apoptosis through both the mitochondrial-induced apoptotic pathway and the death receptor pathway in NRP1+/αvβ3/CTSB+ tumor cells. Furthermore, m(KLA)-iRGD spread extensively within the tumor tissue when it was injected into 4T1 tumor-bearing mice. The m(KLA)-iRGD peptide inhibited tumor growth to a certain degree, resulting in a significant reduction in tumor volume (P < 0.05) and the total inhibition of metastasis at the end of the treatment. These results suggest that m(KLA)-iRGD has the potential for development as a new antitumor drug.

Abstract B40: Tuning exosomes to modulate macrophage inflammation: A therapeutic strategy for melanoma

Abstract Melanoma survival can be dependent in part on tumor associated macrophage (TAM) activity. TAMs can adopt anti- or pro-tumor supportive phenotypes. Melanoma exosomes also can interact with and suppress immune cells. We previously reported that melanoma exosomes naturally home to lymph nodes and prepare them for tumor metastasis. Based on their innate ability to interact with the immune system, we hypothesize that melanoma exosomes might be modified as therapeutic nanocarriers to antagonize macrophage pro-tumor inflammatory processes. Melittin is a 26 amino acid, alpha helical, cytolytic peptide derived from Apis mellifera (honeybee) venom. Melittin enters cell membranes as a monomer where it oligomerizes, creating pores which cause cell death. Recent work has shown melittin to have immunologic adjuvant properties. Loading melittin into the membrane of exosomes should allow for the release of potentially pathogenic RNA content while keeping the exosome structure largely intact. Further, melittin loaded into exosomes will be non-cytotoxic compared to free melittin given that the peptide’s pore forming activity has been neutralized. By precisely dosing B16-F10 melanoma exosomes with melittin, we plan to preserve exosome biophysical properties (size and zeta potential) that allow exosomes to naturally home to and interact with macrophage cells in vitro. B16-F10 melanoma exosomes were cultured and isolated by differential centrifugation. Exosomes were loaded with melittin at different concentrations using simple mixing approaches. Modified exosomes were washed and re-isolated by ultracentrifugation. Exosome membrane loading of melittin peptide was determined using RNA UV absorption. We previously determined that pore formation in exosome membranes can be monitored through exosomal RNA release. The extent to which incorporation of melittin influenced exosome biophysical characteristics was determined using an Izon qViro tunable resistive pulse sensing instrument. RAW 264.7 macrophage cell viability in the presence of melittin modified melanoma exosomes was determined using Life Technologies PrestoBlue cell viability reagent. Induction of inflammatory RAW 264.7 macrophage cytokines was determined using a Qiagen Multi-Analyte ELISArray. Our results demonstrate that melittin can be loaded into melanoma exosome membranes and forms pores as evidenced by RNA release indicating membrane permeability. Loading exosomes with proper amounts of melittin allowed for this permeability without substantially altering key biophysical properties (size and zeta potential) that permit normal trafficking. Melanoma exosomes modified with low concentrations of melittin (0.05 mM) also increased macrophage activity, though to a lesser degree than unmodified melanoma exosomes. Melanoma exosomes modified with high concentrations of melittin (1.0 mM) caused complete macrophage cell death. This suggests an upper limit to melittin loading capacity above which un-neutralized free melittin is likely being carried by exosomes intraluminally. Macrophage cytokine expression profiles differed between unmodified and melittin modified melanoma exosomes treatments. Unmodified melanoma exosomes induced greater macrophage expression of pro-angiogenic IL-1α, G-CSF and the immunosuppressive cytokine IL-10. IL-1α induction by melittin modified melanoma exosomes was less than that of cells cultured in the absence of either exosome type. Melittin modified exosomes induced no expression of the immunosuppressive cytokine IL-10. Collectively, these findings demonstrate the potential use of melittin modified exosomes to antagonize macrophage pro-tumor inflammatory processes. Citation Format: Thomas A. Noel, Joshua L. Hood. Tuning exosomes to modulate macrophage inflammation: A therapeutic strategy for melanoma. [abstract]. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr B40.

Atomic Force Microscopy Top-view Images of the Topographical Surface of Control HeLa Cells

Atomic force microscopy top-view images of the topographical surface of control HeLa cells (A) or after 24 hr of incubation in vitro with a membrane-active and cytolytic peptide (B). The anticancer peptide irreversibly disrupts the cell membrane integrity and releases the intracellular components (Figure 1).

Melittin induced cytogenetic damage, oxidative stress and changes in gene expression in human peripheral blood lymphocytes

Melittin (MEL) is the main constituent and principal toxin of bee venom. It is a small basic peptide, consisting of a known amino acid sequence, with powerful haemolytic activity. Since MEL is a nonspecific cytolytic peptide that attacks lipid membranes thus leading to toxicity, the presumption is that it could have significant therapeutic benefits. The aim was to evaluate the cyto/genotoxic effects of MEL in human peripheral blood lymphocytes (HPBLs) and the molecular mechanisms involved using a multi-biomarker approach. We found that MEL was cytotoxic for HPBLs in a dose- and time-dependent manner. It also induced morphological changes in the cell membrane, granulation and lysis of exposed cells. After treating HPBLs with non-cytotoxic concentrations of MEL, we observed increased DNA damage including oxidative DNA damage as well as increased formation of micronuclei and nuclear buds, and decreased lymphocyte proliferation determined by comet and micronucleus assays. The observed genotoxicity coincided with increased formation of reactive oxygen species, reduction of glutathione level, increased lipid peroxidation and phospholipase C activity, showing the induction of oxidative stress. MEL also modulated the expression of selected genes involved in DNA damage response (TP53, CDKN1A, GADD45α, MDM), oxidative stress (CAT, SOD1, GPX1, GSR and GCLC) and apoptosis (BAX, BCL-2, CAS-3 and CAS-7). Results indicate that MEL is genotoxic to HPBLs and provide evidence that oxidative stress is involved in its DNA damaging effects. MEL toxicity towards normal cells has to be considered if used for potential therapeutic purposes.

Latarcins: versatile spider venom peptides.

Arthropod venoms feature the presence of cytolytic peptides believed to act synergetically with neurotoxins to paralyze prey or deter aggressors. Many of them are linear, i.e., lack disulfide bonds. When isolated from the venom, or obtained by other means, these peptides exhibit common properties. They are cationic; being mostly disordered in aqueous solution, assume amphiphilic α-helical structure in contact with lipid membranes; and exhibit general cytotoxicity, including antifungal, antimicrobial, hemolytic, and anticancer activities. To suit the pharmacological needs, the activity spectrum of these peptides should be modified by rational engineering. As an example, we provide a detailed review on latarcins (Ltc), linear cytolytic peptides from Lachesana tarabaevi spider venom. Diverse experimental and computational techniques were used to investigate the spatial structure of Ltc in membrane-mimicking environments and their effects on model lipid bilayers. The antibacterial activity of Ltc was studied against a panel of Gram-negative and Gram-positive bacteria. In addition, the action of Ltc on erythrocytes and cancer cells was investigated in detail with confocal laser scanning microscopy. In the present review, we give a critical account of the progress in the research of Ltc. We explore the relationship between Ltc structure and their biological activity and derive molecular characteristics, which can be used for optimization of other linear peptides. Current applications of Ltc and prospective use of similar membrane-active peptides are outlined.

Preparation and functional characterization of human vascular endothelial growth factor-melittin fusion protein with analysis of the antitumor activity in vitro and in vivo.

Vascular endothelial growth factor and its tyrosine kinase receptors have been identified as key mediators of the regulation of pathologic blood vessel growth and maintenance in the promotion of angiogenesis and tumor growth. Therefore, an alternative approach to destroying tumor endothelium would be to make this tissue particularly sensitive to VEGF-mediated drug delivery. To verify this hypothesis, we generated a protein containing VEGF165 fused to melittin. Melittin is a small linear peptide composed of 26 amino acid residues that can exert toxic or inhibitory effects on many types of tumor cells. This protein is a cytolytic peptide that attacks lipid membranes, leading to significant toxicity. In the present study, the Pichia pastoris expression system was used to express the fusion protein. Under optimal conditions, stable VEGF165-melittin production was achieved using a series of purification steps. The activity of VEGF165-melittin fusion protein was compared with melittin for its ability to suppress the growth of tumor cell line invitro. The fusion toxin selectively inhibited growth of human hepatocellular carcinoma HepG-2 cell line with high expression of VEGFR-2. We found that sensitivity of VEGFR-2 transfected 293 cells to VEGF165-melittin enhanced as the cellular VEGFR-2 density increased. In an invivo initial experiment, the fusion protein inhibited tumor growth in xenografts assays. Furthermore, successful expression and characterization of the fusion protein demonstrated its efficacy for use as a novel treatment strategy for cancer.

Delivery of a Protease-Activated Cytolytic Peptide Prodrug by Perfluorocarbon Nanoparticles.

Melittin is a cytolytic peptide derived from bee venom that inserts into lipid membranes and oligomerizes to form membrane pores. Although this peptide is an attractive candidate for treatment of cancers and infectious processes, its nonspecific cytotoxicity and hemolytic activity have limited its therapeutic applications. Several groups have reported the development of cytolytic peptide prodrugs that only exhibit cytotoxicity following activation by site-specific proteases. However, systemic administration of these constructs has proven difficult because of their poor pharmacokinetic properties. Here, we present a platform for the design of protease-activated melittin derivatives that may be used in conjunction with a perfluorocarbon nanoparticle delivery system. Although native melittin was substantially hemolytic (HD50: 1.9 μM) and cytotoxic (IC50: 2.4 μM), the prodrug exhibited 2 orders of magnitude less hemolytic activity (HD50: > 100 μM) and cytotoxicity (IC50: > 100 μM). Incubation with matrix metalloproteinase-9 (MMP-9) led to cleavage of the prodrug at the expected site and restoration of hemolytic activity (HD50: 3.4 μM) and cytotoxicity (IC50: 8.1 μM). Incubation of the prodrug with perfluorocarbon nanoparticles led to stable loading of 10,250 peptides per nanoparticle. Nanoparticle-bound prodrug was also cleaved and activated by MMP-9, albeit at a fourfold slower rate. Intravenous administration of prodrug-loaded nanoparticles in a mouse model of melanoma significantly decreased tumor growth rate (p = 0.01). Because MMPs and other proteases play a key role in cancer invasion and metastasis, this platform holds promise for the development of personalized cancer therapies directed toward a patient's individual protease expression profile.

Healthcare- and Community-Associated Methicillin-Resistant Staphylococcus aureus (MRSA) and Fatal Pneumonia with Pediatric Deaths in Krasnoyarsk, Siberian Russia: Unique MRSA's Multiple Virulence Factors, Genome, and Stepwise Evolution.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common multidrug-resistant (MDR) pathogen. We herein discussed MRSA and its infections in Krasnoyarsk, Siberian Russia between 2007 and 2011. The incidence of MRSA in 3,662 subjects was 22.0% and 2.9% for healthcare- and community-associated MRSA (HA- and CA-MRSA), respectively. The 15-day mortality rates for MRSA hospital- and community-acquired pneumonia (HAP and CAP) were 6.5% and 50%, respectively. MRSA CAP cases included pediatric deaths; of the MRSA pneumonia episodes available, ≥27.3% were associated with bacteremia. Most cases of HA-MRSA examined exhibited ST239/spa3(t037)/SCCmecIII.1.1.2 (designated as ST239Kras), while all CA-MRSA cases examined were ST8/spa1(t008)/SCCmecIV.3.1.1(IVc) (designated as ST8Kras). ST239Kras and ST8Kras strongly expressed cytolytic peptide (phenol-soluble modulin α, PSMα; and δ-hemolysin, Hld) genes, similar to CA-MRSA. ST239Kras pneumonia may have been attributed to a unique set of multiple virulence factors (MVFs): toxic shock syndrome toxin-1 (TSST-1), elevated PSMα/Hld expression, α-hemolysin, the staphylococcal enterotoxin SEK/SEQ, the immune evasion factor SCIN/SAK, and collagen adhesin. Regarding ST8Kras, SEA was included in MVFs, some of which were common to ST239Kras. The ST239Kras (strain OC3) genome contained: a completely unique phage, φSa7-like (W), with no att repetition; S. aureus pathogenicity island SaPI2R, the first TSST-1 gene-positive (tst +) SaPI in the ST239 lineage; and a super copy of IS256 (≥22 copies/genome). ST239Kras carried the Brazilian SCCmecIII.1.1.2 and United Kingdom-type tst. ST239Kras and ST8Kras were MDR, with the same levofloxacin resistance mutations; small, but transmissible chloramphenicol resistance plasmids spread widely enough to not be ignored. These results suggest that novel MDR and MVF+ HA- and CA-MRSA (ST239Kras and ST8Kras) emerged in Siberian Russia (Krasnoyarsk) associated with fatal pneumonia, and also with ST239Kras, a new (Siberian Russian) clade of the ST239 lineage, which was created through stepwise evolution during its potential transmission route of Brazil-Europe-Russia/Krasnoyarsk, thereby selective advantages from unique MVFs and the MDR.

EP-100 + paclitaxel to overcome taxane resistance in patients with recurrent LHRH-receptor expressing ovarian cancer.

5582 Background: EP-100 (E) is a synthetic cytolytic peptide conjugated to Luteinizing Hormone Releasing Hormone (LHRH). It targets cells that overexpress LHRH receptors and kills by membrane disru...

Nanoparticle‐Bound Cytolytic Peptide Prodrugs for Cancer Therapy

ObjectiveTo develop a nanoparticle platform which promotes the delivery of cytolytic peptide prodrugs to tumors and their activation by locally produced proteases.Introduction: Melittin is a peptide toxin derived from bee venom which has been proposed as a cancer therapy due to its cytolytic activity. Yet, its therapeutic applications have been limited by its nonspecific cytotoxicity and rapid clearance from the circulation. We have previously developed a prodrug form of melittin which is activated upon cleavage by matrix metalloproteinase 9 (MMP‐9), a protease closely linked with tumor growth and metastasis. Here, we present a platform for delivery of this prodrug based on a perfluorocarbon nanoparticle system designed to enhance intratumoral accumulation while permitting prodrug activation by local MMP‐9 activity.Methods and Results: Incubation of the melittin prodrug with perfluorocarbon nanoparticles (NPs) resulted in stable loading of 10,250 peptides per NP with no significant change in NP size. Addition of 20 nM MMP‐9 led to activation of 57.8% of NP‐bound prodrug within 3 hours. B16F10 melanoma cell viability was virtually eliminated following incubation with 50 μM free or NP‐bound prodrug in the presence of MMP‐9 (p &lt; 0.001 compared to control). In a mouse model of B16F10 lung metastasis, NP accumulation in lung tumors was demonstrated by both fluorescence microscopy (Figure A; NPs in red) and quantitative 19F magnetic resonance spectroscopy (Figure B). Gelatin zymography confirmed production of active MMP‐9 by these tumors.ConclusionPerfluorocarbon nanoparticles accumulate within tumors and permit activation of bound prodrugs, making them promising delivery vehicles for cytolytic peptide agents.Research Support: NIH R01 HL073646 image image

Modeling of the Ebola virus delta peptide reveals a potential lytic sequence motif.

Filoviruses, such as Ebola and Marburg viruses, cause severe outbreaks of human infection, including the extensive epidemic of Ebola virus disease (EVD) in West Africa in 2014. In the course of examining mutations in the glycoprotein gene associated with 2014 Ebola virus (EBOV) sequences, a differential level of conservation was noted between the soluble form of glycoprotein (sGP) and the full length glycoprotein (GP), which are both encoded by the GP gene via RNA editing. In the region of the proteins encoded after the RNA editing site sGP was more conserved than the overlapping region of GP when compared to a distant outlier species, Tai Forest ebolavirus. Half of the amino acids comprising the “delta peptide”, a 40 amino acid carboxy-terminal fragment of sGP, were identical between otherwise widely divergent species. A lysine-rich amphipathic peptide motif was noted at the carboxyl terminus of delta peptide with high structural relatedness to the cytolytic peptide of the non-structural protein 4 (NSP4) of rotavirus. EBOV delta peptide is a candidate viroporin, a cationic pore-forming peptide, and may contribute to EBOV pathogenesis.