Structure and action of heteronemertine polypeptide toxins. Specific cross-linking of Cerebratulus lacteus toxin B-IV to lobster axon membrane vesicles

Lieberman, Deborah L.; Blumenthal, Kenneth M.

doi:10.1016/0005-2736(86)90186-0

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…While binding competition between B-IV and sea anemone or scorpion toxins has not been observed, the capacity of the binding site for Cerebratulus neurotoxin is very similar to that of saxitoxin in the same tissue (16). Furthermore, photoaffinity labeling shows that B-IV binds to a 40-kDa protein on lobster nerve membrane, which is similar in size to the ␤-subunit of mammalian nerve and muscle sodium channels (17). The data above demonstrate that the binding site for B-IV is distinct from sodium channel site III, which is targeted by both ␣-scorpion and sea anemone toxins (16,18).…”

mentioning

confidence: 87%

Role of Electrostatic Interactions in Defining the Potency of Neurotoxin B-IV from Cerebratulus lacteus

Wen

Blumenthal

1996

Journal of Biological Chemistry

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Chemical modification implicates arginine residues of the Cerebratulus lacteus neurotoxin B-IV in biological activity. In the present study, we used site-directed mutagenesis to assess the functional contributions of each of these residues. Panels of mutants at each site have been constructed by polymerase chain reaction and recombinant proteins expressed and purified to homogeneity using an Escherichia coli expression system developed in this laboratory. All substitutions for Arg-17 (Gln, Ala, or Lys) yield proteins having undetectable levels of activity, while charge neutralizing replacement of Arg-25 (R25Q) causes a 400-fold reduction in specific toxicity. However, the R25K mutein is almost as active as natural toxin. Circular dichroism spectroscopy indicates that there are no major conformational changes in any of these muteins. These results therefore demonstrate the requirement for a guanidinium group at position 17, and a positive charge at position 25. NMR analyses (Hansen, P. E., Kem, W. R., Bieber, A. L., and Norton, R. S. (1992) Eur. J. Biochem. 210, 231-240) reveal neurotoxin B-IV to contain two antiparallel ␣-helices, which together include 57% of the sequence. Both Arg-17 and Arg-25 lie on the same face of the N-terminal helix (residues 13-26), as do the carboxyl groups of Glu-13 and Asp-21. However, charge neutralizing mutations of the latter two sites have no effects on biological activity. Arg-34, situated near the N terminus of helix 2 (residues 33-49) is also important for activity, as its replacement by Gln or Ala diminishes activity by 20-and 80-fold, respectively. However, unlike Arg-17 and Arg-25, thermal denaturation experiments suggest that R34Q may be structurally destabilized relative to wild-type B-IV.

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confidence: 87%

Role of Electrostatic Interactions in Defining the Potency of Neurotoxin B-IV from Cerebratulus lacteus

Wen

Blumenthal

1996

Journal of Biological Chemistry

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“…After subsequent SDS-electrophoresis, major bands could be identified for both preparations, which, after correction (B-IV, 125 I-ASA masses subtracted), gave the molecular masses 40 and 38 kDa, matching those of ß 1 and ß 2 subunits of mammalian Na-channels. Accordingly, the authors tentatively suggested that binding occurred at these components of the Na + channel in lobster nerves [96].…”

Section: Ribbon Worm Toxinsmentioning

confidence: 99%

The Toxins of Nemertean Worms

Göransson

Jacobsson

Strand

et al. 2019

Toxins

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Most ribbon worms (phylum: Nemertea) are found in marine environments, where they act as predators and scavengers. They are characterized by an eversible proboscis that isused to hunt for prey and thick mucus covering their skin. Both proboscis and epidermal mucus mediate toxicity to predators and preys. Research into the chemical nature of the substances that render toxicity has not been extensive, but it has nevertheless led to the identification of several compounds of potential medicinal use or for application in biotechnology. This review provides a complete account of the current status of research into nemertean toxins.

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“…The functional characterization of nemertean peptide and protein toxins is limited so far. Cytolytic and hemolytic effects have been reported for A-cytolysin and parborlysin proteins, , and the 55-residue-long and helical neurotoxin B-IV and nemertide α-1 ( 1 ) are paralytic and lethal to crustaceans in sub-nmol/kg doses when injected. ,− Mechanism of action has only been shown for α-1, which binds to Na V channels with high affinity and selectivity, although sodium ion channels have also been suggested to be the target for neurotoxin B-IV . Nemertide α-1 ( 1 ) was found to be exceptionally toxic to green crabs ( Carcinus maenas , lethal at doses above ∼300 pmol/kg) and to cockroaches ( Blaptica dubia , lethal at 2 nmol/kg).…”

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confidence: 99%

Functional Characterization of the Nemertide α Family of Peptide Toxins

et al. 2021

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Peptide toxins find use in medicine, biotechnology, and agriculture. They are exploited as pharmaceutical tools, particularly for the investigation of ion channels. Here, we report the synthesis and activity of a novel family of peptide toxins: the cystine-knotted α nemertides. Following the prototypic α-1 and -2 ( 1 and 2 ), six more nemertides were discovered by mining of available nemertean transcriptomes. Here, we describe their synthesis using solid phase peptide chemistry and their oxidative folding by using an improved protocol. Nemertides α-2 to α-7 ( 2 – 7 ) were produced to characterize their effect on voltage-gated sodium channels ( Blatella germanica BgNa V 1 and mammalian Na V s1.1–1.8). In addition, ion channel activities were matched to in vivo tests using an Artemia microwell assay. Although nemertides demonstrate high sequence similarity, they display variability in activity on the tested Na V s. The nemertides are all highly toxic to Artemia , with EC 50 values in the sub-low micromolar range, and all manifest preference for the insect BgNa V 1 channel. Structure–activity relationship analysis revealed key residues for Na V -subtype selectivity. Combined with low EC 50 values (e.g., Na V 1.1: 7.9 nM (α-6); Na V 1.3: 9.4 nM (α-5); Na V 1.4: 14.6 nM (α-4)) this underscores the potential utility of α-nemertides for rational optimization to improve selectivity.

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Structure and action of heteronemertine polypeptide toxins. Specific cross-linking of Cerebratulus lacteus toxin B-IV to lobster axon membrane vesicles

Cited by 10 publications

References 29 publications

Role of Electrostatic Interactions in Defining the Potency of Neurotoxin B-IV from Cerebratulus lacteus

Role of Electrostatic Interactions in Defining the Potency of Neurotoxin B-IV from Cerebratulus lacteus

The Toxins of Nemertean Worms

Functional Characterization of the Nemertide α Family of Peptide Toxins

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