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At least 19 recordsLinked to original sources
PubMed2006

Genetic mechanisms of scorpion venom peptide diversification.

The diversity of scorpion venom peptides is well shown by the presence of about 400 such polypeptides with or without disulfide bonds. Scorpion toxins with disulfide bonds present a variety of sequence features and pharmacological functions by affecting different ion channels, while the venom peptides without disulfide bonds represent a new subfamily, having much lower sequence homology among each other and different functions (e.g. bradykinin-potentiating, antimicrobial, molecular cell signal initiating and immune modulating). Interestingly, all scorpion venom peptides with divergent functions may have evolved from a common ancestor gene. Over the lengthy evolutionary time, the diversification of scorpion venom peptides evolved through polymorphism, duplication, trans-splicing, or alternative splicing at the gene level. In order to completely clarify the diversity of scorpion toxins and toxin-like peptides, toxinomics (genomics and proteomics of scorpion toxins and toxin-like peptides) are expected to greatly advance in the near future.

Animals↗
PubMed2001

Precursor of a novel scorpion venom peptide (BmKn1) with no disulfide bridge from Buthus martensii Karsch.

A full-length cDNA sequence encoding the precursor of a novel venom peptide (named BmKn1) with no disulfide bridge was first isolated from the venom gland cDNA library of Chinese scorpion Buthus martensii Karsch. The encoded precursor consisted of 70 amino acid residues including two parts: a signal peptide of 23 residues, and a putative mature venom peptide (BmKn1) of 47 residues. The sequence of BmKn1 showed no similarity to those of other scorpion venom peptides. BmKn1 may be the first member of a new venom peptide family from scorpion. Future research will be interesting to unravel further the pharmacological function of this novel scorpion venom peptide.

Amino Acid Sequence↗
PubMed2005

Characterization of a novel cDNA encoding a short venom peptide derived from venom gland of scorpion Buthus martensii Karsch: trans-splicing may play an important role in the diversification of scorpion venom peptides.

A novel cDNA clone (named BmKT-u) which is a hybrid molecule of the 5'-terminal region of BmKT' cDNA and the 3'-terminal region of an undocumented cDNA (named BmKu), was isolated from a cDNA library made from the venom gland of scorpion Buthus martensii Karsch. BmKT-u codes for a 30 amino acid residue precursor peptide composed of a 20-residue signal sequence, and a putative 10-residue novel mature peptide. Northern blot hybridization showed BmKT-u cDNA is generated from a transcript. RT-PCR experiments excluded the possibility that BmKT-u cDNA is an artifact generated during reverse transcription. Genomic amplifications performed with three pairs of BmKT-u gene-specific primers showed the BmKT-u gene does not exist in the genome of the scorpion as a single transcriptional unit. Genomic cloning for BmKT' showed that the BmKT' gene contains an intron of 509 bp inserted into the region encoding the C-terminal region of the signal peptide. A sequence alignment comparison of the cDNA of BmKT-u with genomic BmKT' revealed that the junction site of the hybrid molecule is located at the 5'-splicing site of the intron. The data suggest that the BmKT-u transcript is a naturally occurring mature mRNA that is generated by trans-splicing. Trans-splicing may contribute to the diversity of venom peptides from venomous animals.

Amino Acid Sequence↗
PubMed2006

Molecular dissection of venom from Chinese scorpion Mesobuthus martensii: identification and characterization of four novel disulfide-bridged venom peptides.

Scorpion venom is composed of a large repertoire of biologically active polypeptides. However, most of these peptides remain to be identified and characterized. In this paper, we report the identification and characterization of four novel disulfide-bridged venom peptides (named BmKBTx, BmKITx, BmKKx1 and BmKKx2, respectively) from the Chinese scorpion, Mesobuthus martensii (also named Buthus martensii Karsch). BmKBTx is composed of 58 amino acid residues and cross-linked by three disulfide bridges. The sequence of BmKBTx shows some similarities to that of the toxin, birtoxin, and its analogs. It is likely that BmKBTx is a beta-toxin active on Na+ channels, which is toxic to either insects or mammals. BmKITx is composed of 71 amino acid residues with four disulfide bridges. It is the longest venom peptide identified from M. martensii so far. BmKITx shows little sequence identity with scorpion alpha-toxins toxic to insects. It is likely that BmKITx is a new type of Na+ -channel specific toxin active on both insects and mammals. BmKKx1 contains 38 amino acid residues cross-linked by three disulfide bridges and shows 84% sequence identity with BmTx3, an inhibitor of A-type K+ channel and HERG currents. BmKKx1 has been classified as alpha-KTx-15.8. BmKKx2 is composed of 36 residues and stabilized by three disulfide bridges. BmKKx2 is a new member of the gamma-K+ -channel toxin subfamily (classified as gamma-KTx 2.2). The venoms of scorpions thus continue to provide novel toxins with potential novel actions on targets.

Amino Acid Sequence↗
PubMed2002

Identification of BmKAPi, a novel type of scorpion venom peptide with peculiar disulfide bridge pattern from Buthus martensii Karsch.

A novel cDNA sequence encoding a new type of scorpion venom peptide (BmKAPi) was first isolated from the venom gland of Buthus martensii Karsch by cDNA library screening combined with 5'-race. The encoded precursor of BmKAPi consisted of 89 amino acid residues including a signal peptide of 24 residues, a putative mature peptide of 64 residues (BmKAPi) and an extra basic residue at the C-terminus which might be removed in the post-translational processing. BmKAPi is stabilized by five disulfide bridges, whereas all other disulfide-bridged scorpion toxins described are cross-linked by three or four disulfide bridges. It suggested the three-dimensional scaffold of BmKAPi might be different from other scorpion toxins. The amino acid sequence of BmKAPi showed no homology with other scorpion venom peptides, but shared a little similarity with some anticoagulant peptides and proteinase inhibitors isolated from hookworm, honeybee or European frog, respectively. RT-PCR analysis showed that BmKAPi mRNA could be induced by venom extraction suggesting BmKAPi might be a component of scorpion venom. These results suggest that BmKAPi is a new type of scorpion venom peptide different from other described scorpion toxins in structural and functional aspects.

Amino Acid Sequence↗
PubMed2005

Scorpion venom peptides without disulfide bridges.

Several hundred disulfide-bridged neurotoxic peptides have been characterized from scorpion venom; however, only few scorpion venom peptides without disulfide bridges have been identified and characterized. These non-disulfide-bridged peptides (NDBPs) are a novel class of molecules because of their unique antimicrobial, immunological or cellular signaling activities. This review provides an overview of their structural simplicity, precursor processing, biological activities and evolution, and sheds insight into their potential clinical and agricultural applications. Based on their pharmacological activities and peptide size similarity, we have classified these peptides into six subfamilies.

Amino Acid Sequence↗
PubMed2004

Identification and functional characterization of novel scorpion venom peptides with no disulfide bridge from Buthus martensii Karsch.

The scorpion venom peptides with no disulfide bridge are rarely identified and poorly characterized so far. Here, we report the identification and characterization of four novel disulfide-bridge-free venom peptides (BmKa1, BmKa2, BmKb1 and BmKn2) from Buthus martensii Kasch. BmKa1 and BmKa2 are very acidic and hydrophilic, showing no any similarity to other proteins, whereas BmKb1 and BmKn2 both are basic, alpha-helical peptide with an amidated C-terminus, showing a little homology with other peptides. Functional tests with synthetic peptide showed that BmKn2 has strong antimicrobial activity against both Gram-positive and Gram-negative bacteria, whereas BmKb1 has weak activity in inhibiting the growth of these bacteria.

Amino Acid Sequence↗
PubMed2001

Genomic organization of BmTXKbeta and BmTXKS2, two scorpion venom peptides from Buthus martensii Karsch.

To elucidate genomic organization of BmTXKbeta and BmTXKS2, two scorpion venom peptides from Chinese scorpion Buthus martensii Karsch(BmK) were first isolated and their genomic regions characterized using the PCR method. Analysis of nucleotide sequence shows that there exists different intron location in the venom genes. The region encoding mature peptide of BmTXKbeta is disrupted by an intron with 886 bp, whereas the intron of BmTXKS2 is located within its propeptide coding region, which is different from other scorpion toxin genes with their introns within the signal peptide coding region.

Amino Acid Sequence↗
PubMed1999

Induction of seizures by the potent K+ channel-blocking scorpion venom peptide toxins tityustoxin-K(alpha) and pandinustoxin-K(alpha).

The scorpion venom peptide toxins tityustoxin-K(alpha) (TsTx-K(alpha)) and pandinustoxin-K(alpha) (PiTx-K(alpha)) are novel, highly potent and selective blockers of voltage-activated K+ channels. PiTx-K(alpha) preferentially blocks rapidly inactivating (A-type) K+ channels whereas TsTx-K(alpha) is selective for slowly inactivating (delayed rectifier-type) channels. K+ channel blockers are known to induce seizures, but the specific K channel types that can serve as convulsant targets are not well defined. To address this issue, we examined for convulsant activity the K+ channel type-specific scorpion toxins and the selective K+ channel antagonists 4-aminopyridine (4-AP), an inhibitor of A-type voltage-activated K+ channels, and paxilline, a selective blocker of large conductance (maxi K) Ca(2+)-activated K+ channels. Intracerebroventricular injection of recombinant TsTx-K(alpha) and PiTx-K(alpha) in mice produced limbic and clonic-tonic seizures. The severity of the seizures increased during the 60-min period following injection, culminating in continuous clonic seizure activity (status epilepticus), tonic hindlimb extension, and eventually in death. The estimated doses producing limbic and clonic seizures in 50% of animals (CD50) for TsTx-K(alpha) and PiTx-K(alpha) were 9 and 33 ng, respectively. 4-AP produced seizure activity similar to the toxins (CD50, 76 ng) whereas paxilline failed to induce seizures at doses up to 13.5 microg. Carbamazepine protected fully against the toxin- and 4-AP-induced seizures whereas phenytoin had variable activity against the clonic component although it was protective against tonic hindlimb extension. The AMPA receptor antagonist GYKI 52466 also conferred full protection against toxin-induced seizures, but the NMDA receptor antagonists (R)-CPP and dizocilpine failed to affect limbic and clonic seizures, although they protected against hindlimb extension. We conclude that selective blockade of delayed rectifier- or A-type voltage-activated K+ channels can produce limbic, clonic and tonic seizures, whereas blockade of maxi K-type Ca(2+)-activated K+ channels does not. The convulsant effects may be related to enhanced glutamate release and, in the case of the limbic and clonic convulsions, activation of AMPA receptors.

4-Aminopyridine↗
PubMed2026

Scorpion venom peptides: Novel therapeutic approaches for inflammatory and hepatic disorders.

Chronic hepatic disorders, such as metabolic dysfunction associated steatohepatitis (MASH), alcohol associated liver disease (ALD), and viral hepatitis (Hepatitis B virus [HBV]/Hepatitis C virus [HCV]), are primarily driven by persistent immune-mediated inflammation and hepatic stellate cell activation leading to fibrosis, yet conventional therapies lack tissue and molecular specificity. Scorpion venom peptides, refined through evolutionary selection, provide highly potent, target specific scaffolds capable of modulating intrahepatic inflammatory networks. Recent in vivo preclinical studies indicate that voltage gated potassium (Kv1.3) channel blocking peptides, such as BmKK2, significantly reduce macrophage activation and inhibit downstream cytokine production, effectively ameliorating diet-induced steatohepatitis and tissue scarring in murine models. Engineered hepatotropic candidates, such as Smp76 and Mucroporin-M1, demonstrate dual therapeutic functions: they neutralize extracellular Hepatitis C particles and suppress key host transcription factors necessary for Hepatitis B replication. This review systematically examines scorpion venom peptides organized by disease category, covering their historical development, structural classification into disulfide-bridged and non-disulfide-bridged families, ion channel specificity, hepatic anti-inflammatory and antiviral mechanisms, and translational challenges including nano-formulation delivery strategies and computational drug design. These target-specific peptides are ultimately positioned as promising molecular leads that may bridge targeted immunomodulation with the resolution of chronic, progressive liver injury.

Anti-inflammatory effects↗
PubMed2003

Expression, purification and functional characterization of a recombinant scorpion venom peptide BmTXKbeta.

BmTXKbeta, a scorpion toxin isolated from the Chinese scorpion Buthus martensii Karsch (BmK), was expressed as a GST fusion protein in BL21 (DE3) strain. The recombinant GST-BmTXKbeta protein was purified by affinity chromatography. When treated with enterokinase, the GST-BmTXKbeta fusion protein released an approximate 6.5kDa protein which was the expected size for correctly processed. About 2mg purified recombinant BmTXKbeta protein (rBmTXKbeta) was produced from 1l bacterial culture, using this expression and purification system. The function of rBmTXKbeta was studied on the rabbit atrial myocyte by whole-cell patch clamp technique. The results showed that rBmTXKbeta inhibited the transient outward current (I(to)) of rabbit atrial myocyte with recovery after washout and the inhibition was concentration-dependent. The rBmTXKbeta prolonged the action potential duration of rabbit atrial myocyte in a concentration-dependent manner, whereas it did not affect the action potential amplitude.

Action Potentials↗
PubMed2004

A scorpion venom peptide fraction induced prostaglandin biosynthesis in guinea pig kidneys: incorporation of 14C-linoleic acid.

A peptide fraction isolated from the venom of the Egyptian scorpion Buthus occitanus was proved to have a bradykinin- potentiating activity. In vivo and in vitro modes of action of the isolated bradykinin-potentiating peptide (BPP) on kidneys of guinea pigs were investigated. Animals received five successive i.p. doses of the scorpion BPP (1 microg/g body weight) at one-week intervals. The control animals were i.p. injected with saline solution only. In vivo experiments showed a significant increase in renal tissue PGE(2) content and lipid peroxides of the treated guinea pigs compared to the control animals (p < 0.05). Nonsignificant changes were detected in the levels of tissue c-AMP and 5-nucleotidase activity (p > 0.05) of the treated animals, while the changes in c-GMP and c-AMP/c-GMP ratio were both significant (p < 0.05). In vitro experiments demonstrated enhanced capacity of guinea pig-renal tissue to convert (14)C-linoleic acid to its metabolites, 6-keto-PGF(1)alpha, PGF(2)alpha, PGE(2), TxB(2), PGD(2), and arachidonic acid, in response to the added PBP (1 microg/ml) and bradykinin (1 microg/ml). This enhanced response was abolished upon the addition of 1 microg/ml of BK-inhibitor (D-Arg- [Hyp(3), Thi(5,6), Phe(7)]). The capacity for labeled metabolites recovery in BPP treated renal tissue was 19.78%, while it was 13.00% in the basal control. The total increase that evoked by BPP was 62.78%. The results clearly indicate that the isolated BPP induced prostaglandin biosynthesis, which may trigger enhanced glomerular filtration in guinea pigs.

Animals↗
PubMed2004

Inhibition of CFTR channels by a peptide toxin of scorpion venom.

Peptide toxins have been valuable probes in efforts to identify amino acid residues that line the permeation pathway of cation-selective channels. However, no peptide toxins have been identified that interact with known anion-selective channels such as the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR channels are expressed in epithelial cells and are associated with several genetic disorders, including cystic fibrosis and polycystic kidney disease. Several organic inhibitors have been used to investigate the structure of the Cl- permeation pathway in CFTR. However, investigations of the wider cytoplasmic vestibule have been hindered by the lack of a high-affinity blocker that interacts with residues in this area. In this study we show that venom of the scorpion Leiurus quinquestriatus hebraeus reversibly inhibits CFTR, in a voltage-independent manner, by decreasing single-channel mean burst duration and open probability only when applied to the cytoplasmic surface of phosphorylated channels. Venom was able to decrease burst duration and open probability even when CFTR channels were locked open by treatment with either vanadate or adenosine 5'-(beta,gamma-imido)triphosphate, and block was strengthened on reduction of extracellular Cl- concentration, suggesting inhibition by a pore-block mechanism. Venom had no effect on ATP-dependent macroscopic opening rate in channels studied by inside-out macropatches. Interestingly, the inhibitory activity was abolished by proteinase treatment. We conclude that a peptide toxin contained in the scorpion venom inhibits CFTR channels by a pore-block mechanism; these experiments provide the first step toward isolation of the active component, which would be highly valuable as a probe for CFTR structure and function.

Animals↗
PubMed2006

Molecular characterization of a new scorpion venom lipolysis activating peptide: Evidence for disulfide bridge-mediated functional switch of peptides.

Venoms from scorpions contain extremely rich bioactive peptides that often carry diverse functions and are presumably needed to achieve synergistic effects for rapidly immobilizing prey and defending themselves. BotLVP1 is a unique heterodimer protein recently found in the scorpion Buthus occitanus tunetanus venom that is structurally related to scorpion toxins affecting sodium channels (NaScTxs) but exhibits adipocyte lipolysis activity. We have isolated and identified two cDNA clones encoding subunits alpha and beta of a BotLVP1-like peptide (named BmLVP1) from the Chinese scorpion Buthus martensii venom gland and determined the first complete gene structure of this subfamily. These results highlight a genetic link between these lipolysis activating peptides and NaScTxs. Comparison of cDNA and genomic sequences combined with protein structural and functional analysis provides evidence supporting the existence of RNA editing mechanism in scorpion venom glands, which could mediate functional switch of BmLVP1 gene, from adipocyte lipolysis to neurotoxicity, by altering the wrapper disulfide bridge (WDB) pattern of the peptides.

Adenine↗
PubMed2002

Cationic peptides from scorpion venom can stimulate and inhibit polymorphonuclear granulocytes.

We have isolated two cationic peptides, sharing partial homology with each other, from the venom of South African scorpions. Both synthetic peptides-one containing 44 amino acids, the other containing 45 amino acids-were constructed. At submicromolar concentrations they can activate granulocytes as evidenced by a concentration dependent chemotaxis and exocytosis. They also strongly inhibit the production of superoxide anions. At higher concentrations they act as pore formers and induce leakage of the cells. These different effects may be related to their amphipathic structure.

Amino Acid Sequence↗
PubMed2000

Evidence for the existence of insect defensin-like peptide in scorpion venom.

Insect defensin refers to a group of antibacterial peptides derived from a variety of insect species as well as from scorpion and possessing a three-dimensional structure highly similar to that of scorpion toxins. A full-length cDNA encoding an insect defensin-like peptide was isolated from the venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch. The precursor, the overall organization of which is similar to that of insect defensins, consists of 61 amino acid residues with a putative signal peptide of 15 residues, a propeptide of 7 residues, and a mature peptide of 39 residues (named BmTXKS2). The positions of six cysteines and a conserved glycine in mature BmTXKS2 are the same as those in LqDef, the first defensin found in scorpions, which suggests these peptides should present a similar cysteine-stabilized alphabetamotif. Phylogenetic analysis further shows that the structure of BmTXKS2 is closer to that of ancient defensins (e.g., LqDef and AaDef, two insect defensins present in the scorpion hemolymph) than to scorpion toxins.

Amino Acid Sequence↗
PubMed2002

Antibacterial and antifungal properties of alpha-helical, cationic peptides in the venom of scorpions from southern Africa.

Two novel pore-forming peptides have been isolated from the venom of the South-African scorpion Opistophtalmus carinatus. These peptides, designated opistoporin 1 and 2, differ by only one amino acid and belong to a group of alpha-helical, cationic peptides. For the first time, a comparison of the primary structures of alpha-helical pore-forming peptides from scorpion venom was undertaken. This analysis revealed that peptides in the range of 40-50 amino acids contain a typical scorpion conserved sequence S(x)3KxWxS(x)5L. An extensive study of biological activity of synthesized opistoporin 1 and parabutoporin, a pore-forming peptide previously isolated from the venom of the South-African scorpion Parabuthus schlechteri, was undertaken to investigate an eventual cell-selective effect of the peptides. Opistoporin 1 and parabutoporin were most active in inhibiting growth of Gram-negative bacteria (1.3-25 micro m), while melittin and mastoparan, two well-known cytolytic peptides, were more effective against Gram-positive bacteria in the same concentration range. In addition, the peptides showed synergistic activity with some antibiotics commonly used in therapy. Opistoporin 1 and parabutoporin had hemolytic activity intermediate between the least potent mastoparan and the highly lytic melittin. Furthermore, all peptides inhibited growth of fungi. Experiments with SYTOX green suggested that this effect is related to membrane permeabilization.

Africa, Southern↗
PubMed2004

Morphofunctional changes in incubated Mauthner neurons in goldfish treated with peptides from scorpion venom.

Electron microscopy with negative contrast showed that direct interaction of one of the peptide fractions of scorpion venom with monomeric chromatographically pure actin led to polymerization of actin, transforming it from the globular form to the fibrillar form. The effects of prolonged orthodromic stimulation on the evoked electrical activity and ultrastructure of Mauthner neurons (MN) were studied in incubated slices of goldfish medulla oblongata in the presence of this actin-polymerizing venom fraction. Peptides in this fraction were found to stabilize the amplitude of the electrical response of MN to exhaustion and to protect the ultrastructure of afferent chemical synapses and the neurons themselves from damage induced by stimulation. Enhancements in morphofunctional resistance were accompanied by stabilization of actin-containing specialized synaptic structures--desmosome-like contacts. The data obtained here provide evidence that peptides of this fraction of scorpion venom have direct actions on the actin component of the MN cytoskeleton and demonstrate potential for its use as a pharmacological tool able to penetrate living cells with value for studying the role of actin in the mechanisms of adaptation and memory.

Animals↗