[Show abstract][Hide abstract] ABSTRACT: Five novel antimicrobial peptides (temporin-LK1, rugosin-LK1, rugosin-LK2, gaegurin-LK1, and gaegurin-LK2) are purified and characterized from Kuhl's wart frog skin secretions, Limnonectes kuhlii. They share obvious similarity to temporin, rugosin, and gaegurin antimicrobial peptide family, respectively. Their amino acid sequences were determined by Edman degradation and mass spectrometry, and further confirmed by cDNA cloning. Nine cDNA sequences encoding precursors of these five purified antimicrobial peptides and other four hypothetical antimicrobial peptides were cloned from the skin cDNA library of L. kuhlii. The deduced precursors are composed of a predicted signal peptide, an acidic spacer peptide, and a mature antimicrobial peptide. Most of them showed strong antimicrobial activities against Gram-positive and Gram-negative bacteria and fungi. The current work identified and characterized three families of antimicrobial peptides from L. kuhlii skins and confirmed that the genus of Limnonectes amphibians share similar antimicrobial peptide families with the genus of Rana amphibians. In addition, a unique antimicrobial peptide (temporin-LK1) with 17 residues including four phenylalanines, which is significantly different from other temporins (16 residues, one or two phenylalanines), was identified in this work. Such unique structure might provide novel template or leading structure to design antimicrobial agents.
Full-text · Article · Oct 2012 · Molecular Biology Reports
[Show abstract][Hide abstract] ABSTRACT: Due to poor diagnostic facilities and a lack of medical alertness, allergy to Vespa wasps may be underestimated. Few allergens have been identified from Vespa wasps.
Possible native allergen proteins were purified from the wasp venoms (WV) (Vespa magnifica Smith) by gel filtration, ion exchange chromatography, respectively. Their sequences were determined by Edman degradation and cDNA cloning. Their allergenicities were assayed by enzyme-linked immunosorbent assay inhibition tests (ELISA-IT), immunoblots, and skin prick tests (SPTs). Their cross allergencities with Tab y 2 and Tab y 5 purified from the horsefly (Tabanus yao Macquart) were also determined. Two native allergens were identified from the WV, respectively. They are a 25-KDa antigen 5 protein (Ag5) (Vesp ma 5) and a 35-KDa hyaluronidase (Vesp ma 2). They represented major allergens in Vespa magnifica by immunoblots and SPTs. ELISA inhibition of pooled sera IgE reactivity to both the WV and the horsefly salivary gland extracts (HSGE) using four purified allergens (Vesp ma 2, Vesp ma 5 and previously purified Tab y 2 and Tab y 5) was significant. Their cross allergenicities were confirmed by ELISA-IT, immunoblots, and SPTs. They represented the cross reactive allergens from wasp and horsefly and proved the so called wasp-horsefly syndrome.
[Show abstract][Hide abstract] ABSTRACT: Cathelicidins comprise a family of antimicrobial peptides (AMPs) sharing a highly conserved cathelin domain, and play a central role in the innate defense against infection in most of vertebrates. But so far it has not yet been found in amphibians although a large number of other groups of AMPs have been identified. In the current work, the first amphibian cathelicidin (cathelicidin-AL) has been characterized from the frog skin of Amolops loloensis. Cathelicidin-AL (RRSRRGRGGGRRGGSGGRGGRGGGGRSGAGSSIAGVGSRGGGGGRHYA) is a cationic peptide containing 48 amino acid residues (aa) with 12 basic aa and no acidic aa. The chemical synthesized peptide efficiently killed bacteria and some fungal species including clinically isolated drug-resistance microorganisms. The cDNA encoding cathelicidin-AL precursor was cloned from the skin cDNA library of A. loloensis. As other cathelicidins, the precursor of cathelicidin-AL also contains highly conserved anionic cathelin domain of cysteine proteinase inhibitor followed by the AMP fragment at C-terminus. Phylogenetic analysis revealed that as connecting link, the amphibian cathelicidin predates reptilia but postdates fish cathelicidin. The peptide purification combined with gene cloning results confirms the presence of cathelicidin in amphibians and filled the evolutionary gap of cathelicidin in vertebrate, considering amphibians' special niche as the animals bridging the evolutionary land-water gap.
[Show abstract][Hide abstract] ABSTRACT: The question of how amphibians can protect themselves from reactive oxygen species when exposed to the sun in an oxygen-rich atmosphere is important and interesting, not only from an evolutionary viewpoint, but also as a primer for researchers interested in mammalian skin biology, in which such peptide systems for antioxidant defense are not well studied. The identification of an antioxidant peptide named antioxidin-RL from frog (Odorrana livida) skin in this report supports the idea that a peptide antioxidant system may be a widespread antioxidant strategy among amphibian skins. Its ability to eliminate most of the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical tested within 2 s, which is much faster than the commercial antioxidant factor butylated hydroxytoluene, suggests that it has a potentially large impact on redox homeostasis in amphibian skins. Cys10 is proven to be responsible for its rapid radical scavenging function and tyrosines take part in the binding of antioxidin-RL to radicals according to our nuclear magnetic resonance assay.
Full-text · Article · Feb 2010 · Free Radical Biology and Medicine
[Show abstract][Hide abstract] ABSTRACT: Ticks are blood-feeding arthropods that may secrete immunosuppressant molecules, which inhibit host inflammatory and immune
responses and provide survival advantages to pathogens at tick bleeding sites in hosts. In the current work, two families
of immunoregulatory peptides, hyalomin-A and -B, were first identified from salivary glands of hard tick Hyalomma asiaticum asiaticum. Three copies of hyalomin-A are encoded by an identical gene and released from the same protein precursor. Both hyalomin-A
and -B can exert significant anti-inflammatory functions, either by directly inhibiting host secretion of inflammatory factors
such as tumor necrosis factor-α, monocyte chemotectic protein-1, and interferon-γ or by indirectly increasing the secretion
of immunosuppressant cytokine of interleukin-10. Hyalomin-A and -B were both found to potently scavenge free radical in vitro in a rapid manner and inhibited adjuvant-induced inflammation in mouse models in vivo. The JNK/SAPK subgroup of the MAPK signaling pathway was involved in such immunoregulatory functions of hyalomin-A and -B.
These results showed that immunoregulatory peptides of tick salivary glands suppress host inflammatory response by modulating
cytokine secretion and detoxifying reactive oxygen species.
Preview · Article · Feb 2010 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: While investigating antimicrobial peptide diversity of Amolops loloensis, five novel antimicrobial peptides belonging to two families were identified from skin secretions of this frog. The first family including two members is esculentin-2-AL (esculentin-2-ALa and -ALb); the second family including three members is temporin-AL (temporin-ALd to -ALf). The family of esculentin-2-AL is composed of 37 amino acid residues (aa); the family of temporin-AL is composed of 16, 13 and 10 aa, respectively. All of these antimicrobial peptides showed antimicrobial activities against tested microorganisms. cDNAs encoding precursors of esculentin-2-ALs and temporin-ALs were cloned from the skin cDNA library of A. loloensis. All the precursors share similar overall structures. There is a typical prohormone processing signal (Lys-Arg) located between the acidic propiece and the mature peptide. The antimicrobial peptide family of esculentin-2 is firstly reported in the genus of Amolops. Combined with previous reports, a total of four antimicrobial peptide families have been identified from the genus of Amolops; three of them are also found in the genus of Rana. These results suggest the possible evolutionary connection between the genera Amolops and Rana.
No preview · Article · Oct 2009 · Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology
[Show abstract][Hide abstract] ABSTRACT: The Ag5 proteins are the most abundant and immunogenic proteins in the venom secretory ducts of stinging insects. An antigen 5-like protein (named tabRTS) composed of 221 amino acid residues was purified and characterized from the salivary glands of the horsefly, Tabanus yao (Diptera, Tabanidae). Its cDNA was cloned from the cDNA library of the horsefly's salivary gland. TabRTS containing the SCP domain (Sc7 family of extracellular protein domain) was found in insect antigen 5 proteins. More interestingly, there is an Arg-Thr-Ser (RTS) disintegrin motif at the C-terminus of tabRTS. The RTS motif is positioned in a loop bracketed by cysteine residues as those found in RTS-disintegrins of Crotalidae and Viperidae snake venoms, which act as angiogenesis inhibitors. Endothelial Cell Tube formation assay in vitro and chicken chorioallantoic membrane (CAM) angiogenesis assay in vivo were performed as to investigate the effect of tabRTS on angiogenesis. It was found that tabRTS could significantly inhibit angiogenesis in vitro and in vivo. Anti-alpha(1)beta(1) monoclonal antibody could dose-dependently inhibit the anti-angiogenic activity of tabRTS. This result indicated that tabRTS possibly targets the alpha(1)beta(1) integrin to exert the anti-angiogenic activity as snake venom RTS-/KTS-disintegrins do. The current work revealed the first angiogenesis inhibitor protein containing RTS motif from invertebrates, a possible novel type of RTS-disintegrin.
[Show abstract][Hide abstract] ABSTRACT: Blood-feeding arthropods rely heavily on the pharmacological properties of their saliva to get a blood meal and suppress immune reactions of hosts. Little information is available on antihemostatic substances in horsefly salivary glands although their saliva has been thought to contain wide range of physiologically active molecules. In traditional Eastern medicine, horseflies are used as anti-thrombosis material for hundreds of years. By proteomics coupling transcriptome analysis with pharmacological testing, several families of proteins or peptides, which exert mainly on anti-thrombosis functions, were identified and characterized from 60,000 pairs of salivary glands of the horsefly Tabanus yao Macquart (Diptera, Tabanidae). They are: (I) ten fibrin(ogen)olytic enzymes, which hydrolyze specially alpha chain of fibrin(ogen) and are the first family of fibrin(ogen)olytic enzymes purified and characterized from arthropods; (II) another fibrin(ogen)olytic enzyme, which hydrolyzes both alpha and beta chain of fibrin(ogen); (III) ten Arg-Gly-Asp-motif containing proteins acting as platelet aggregation inhibitors; (IV) five thrombin inhibitor peptides; (V) three vasodilator peptides; (VI) one apyrase acting as platelet aggregation inhibitor; (VII) one peroxidase with both platelet aggregation inhibitory and vasodilator activities. The first three families are belonging to antigen five proteins, which show obvious similarity with insect allergens. They are the first members of the antigen 5 family found in salivary glands of blood sucking arthropods to have anti-thromobosis function. The current results imply a possible evolution from allergens of blood-sucking insects to anti-thrombosis agents. The extreme diversity of horsefly anti-thrombosis components also reveals the anti-thrombosis molecular mechanisms of the traditional Eastern medicine insect material.
[Show abstract][Hide abstract] ABSTRACT: Horseflies are economically important blood-feeding arthropods and also a nuisance for humans and vectors for filariasis. They rely heavily on the pharmacological properties of their saliva to get a blood meal and suppress immune reactions of hosts. Little information is available on antihemostatic substances in horsefly salivary glands; especially no horsefly immune suppressants have been reported. By proteomics or peptidomics and coupling transcriptome analysis with pharmacological testing, several families of proteins or peptides, which act mainly on the hemostatic system or immune system of the host, were identified and characterized from 30,000 pairs salivary glands of the horsefly Tabanus yao (Diptera, Tabanidae). They are: (i) a novel family of inhibitors of platelet aggregation including two members, which possibly inhibit platelet aggregation by a novel mechanism and act on platelet membrane, (ii) a novel family of immunosuppressant peptides including 12 members, which can inhibit interferon-gamma production and increase interleukin-10 secretion, (iii) a serine protease inhibitor with 56 amino acid residues containing anticoagulant activity, (iv) a serine protease with anticoagulant activity, (v) a protease with fibrinogenolytic activity, (vi) three families of antimicrobial peptides including six members, (vii) a hyaluronidase, (viii) a vasodilator peptide, which is an isoform of vasotab identified from Hybomitra bimaculata, and interestingly (ix) two metallothioneins, which are the first metallothioneins reported from invertebrate salivary glands. The current work will facilitate the understanding of the molecular mechanisms of the ectoparasite-host relationship and help in identifying novel vaccine targets and novel leading pharmacological compounds.
[Show abstract][Hide abstract] ABSTRACT: Wasp is an important venomous animal that can induce human fatalities. Aortic thrombosis and cerebral infarction are major clinical symptoms after massive wasp stings but the reason leading to the envenomation manifestation is still not known. In this paper, a toxin protein is purified and characterized by Sephadex G-75 gel filtration, CM-Sephadex C-25 cationic exchange and fast protein liquid chromatography (FPLC) from the venom of the wasp, Vespa magnifica (Smith). This protein, named magnifin, contains phospholipase-like activity and induces platelet aggregation. The cDNA encoding magnifin is cloned from the venom sac cDNA library of the wasp. The predicted protein was deduced from the cDNA with a sequence composed of 337 amino acid residues. Magnifin is very similar to other phospholipase A(1) (PLA(1)), especially to other wasp allergen PLA(1). Magnifin can activate platelet aggregation and induce thrombosis in vivo. The current results proved that PLA(1) in wasp venom could be contributable to aortic thrombosis after massive wasp stings.
[Show abstract][Hide abstract] ABSTRACT: Despite the evolutional distance between wasp and amphibian, vespid chemotactic peptide (VCP), an important component of wasp venom, are found sharing remarkable similarities with the temporin antimicrobial peptides (AMPs) from Ranid frog, Amolops loloensis. Not only their amino acid sequences are highly similar, but they are both microbe-killing and can induce the cellular chemotactic response. However, whether the two peptides possess identical biosynthesis pathway was still not clear due to the unsolved gene sequence of VCP putative precursor. In this paper, a cDNA encoding one of VCP precursors was cloned from the venom sac cDNA library of the wasp, Vespa magnifica (Smith), and the corresponding native VCP was purified from the venoms. It was shown that the VCP precursor highly resembled temporin precursor not only in the sequence size but also in the sequences of their corresponding mature peptides. However, the enzyme-cutting sites and the possible processing enzymes for both peptides were different, which for VCP were dipeptidyl peptidase IV and trypsin-like proteases, while for temporin were only trypsin-like protease. The current results suggested that the biosynthesis mode of VCP was different from that of temporin AMP, even though the two mature peptides were similar in many ways. It is also the first report about VCP precursor from wasp venom.
[Show abstract][Hide abstract] ABSTRACT: Group IIA secretory phospholipases A(2) (sPLA(2)-II) is generally known to display potent gram-positive bactericidal activity, while group IA sPLA(2) (sPLA(2)-I) reportedly is not. In this work, a novel sPLA(2)-I named BFPA was identified from Bungarus fasciatus venom, and its antimicrobial activity was studied as well. The amino acid sequence of the venomous protein precursor was 145-amino acid in length, and contained a predicted 27-amino acid signal peptide and a 118-amino acid mature protein. Unlike the well-known sPLA(2)-Is, which have 14 half-cysteines forming 7 intramolecular disulfide bridges, BFPA possesses 15 half-cysteines. The additional cysteine might contribute to the formation of an intermolecular disulfide bridge of the homodimeric protein. In the biological activities assays, BFPA displayed the activities of anticoagulation and bactericidal against Escherichia coli and Staphylococcus aureus. This study is the first report about gram-positive bactericidal activity of sPLA(2)-I.
[Show abstract][Hide abstract] ABSTRACT: There are around 27 species of Amolops amphibian distributed in South-east of Asia. Seven antimicrobial peptides (AMPs) belonging to two different families were purified from skin of rufous-spotted torrent frog, Amolops loloensis, and designated brevinins-ALa, b, c, and d, and temporins-ALa, b, and c. The brevinins-AL family which is structurally related to brevinins-1 from skin secretions of the European frog, Rana brevipoda, is composed of 24 amino acids and has an intra-disulfide bridge at the C-terminus. The temporins-AL family, composed of 13 or 16 amino acid residues, is related with temporins from the skin secretions of R. temporaria. The findings of this study will facilitate the solutions to the taxonomic questions of the ranid genus Amolops and Staurois. In the work of this paper, both brevinins-ALb and temporin-Ma induced mast cell degranulation and histamine release, and had cytotoxic activity toward solid tumor cell line HepG(2). Brevinins-ALb also exerted strong hemolytic activity while temporin-Ma had no such activity.