Pore-forming toxins

Gilbert, Robert J.C.

doi:10.1007/s00018-002-8471-1

Cited by 170 publications

(144 citation statements)

References 93 publications

Supporting

Mentioning

139

Contrasting

Order By: Relevance

“…In this study, the results of protease digestion of membrane-bound VVA2 showed that the proteolysis-resistant region of VVA2 encompasses the amphipathic ␤-strands, being corresponding to those of CytB. Thus, the ␤-barrel might be involved in membrane insertion, and VVA2 could be classified as a ␤-pore-forming toxin based on its ␤-barrel insertion structure (8,34).…”

Section: Discussionmentioning

confidence: 78%

Functional Domains of a Pore-forming Cardiotoxic Protein, Volvatoxin A2

Weng

Lin

Hsu

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

Volvatoxin A2 (VVA2), a novel pore-forming cardiotoxic protein was isolated from the mushroom Volvariella volvacea. We identified an N-terminal fragment (NTF) (1-127 residues) of VVA2 as a domain for oligomerization by limited tryptic digestion. On preincubation of NTF with VVA2, NTF was found to inhibit VVA2 hemolytic activity by inducing VVA2 oligomerization in the solution in the same manner as liposomes. By site-directed mutagenesis, the amphipathic ␣-helix B of NTF or VVA2 was shown to be indispensable for its biological functions. Interestingly, at a molar ratio of recombinant NTF (reNTF)/VVA2 as low as 0.01, reNTF was able to inhibit VVA2 hemolytic activity and induce VVA2 oligomerization. This indicates that reNTF can trigger VVA2 oligomerization by a seeding effect. Furthermore, the recombinant C-terminal fragment (128 -199 residues) was found to be a functional domain that mediates the membrane binding of VVA2. We found a fragment localized at the C-terminal half of VVA2 containing ␤6, -7, and -8, which is protected from protease digestion because of its insertion of a membrane. We also identified a putative heparin binding site (HBS) located in the VVA2 C terminus (166 -194 residues), which was conserved among 10 kinds of snake venom cardiotoxins. VVA2 or the reHBS fragment was shown to interact with sulfated glycoaminoglycans by affinity column chromatography. The finding of a higher number of glycoaminoglycans in the membrane of cardiac myocytes suggested that they could be the specific membrane target for VVA2. Taken together, these findings indicate that VVA2 contains two functional domains, NTF and CTF. The NTF domain is responsible for VVA2 oligomerization and the CTF domain for membrane binding and insertion. Our results support a model whereby the formation of VVA2 oligomeric pre-pore complexes precedes their membrane insertion.Volvatoxin A (VVA), 1 first isolated from the edible mushroom Volvariella volvacea (1, 2), is a novel pore-forming cardiotoxic protein that causes cardiac arrest by activation of Ca 2ϩ -dependent ATPase activity and inhibition of Ca 2ϩ accumulation in the microsomal fraction of the sarcoplasmic recticulum of the ventricular muscle (3). VVA is composed of VVA1 and VVA2, of which only VVA2 is endowed with hemolytic and cytotoxic activity (1). Our previous studies showed that VVA2 consists of 199 amino acid residues without cysteine residues, and that it forms pores in response to its oligomer formation in human erythrocyte membranes and liposomes. This toxic protein also permeabilized the cell membrane and allowed the passage of 70-kDa dextran rhodamine B into cultured Xenopus myocytes. Furthermore, conformational changes occurred when VVA2 interacted with liposomes (2).Naturally occurring hemolytic toxic proteins can be classified into three groups based on their mechanisms of lysis of red blood cells: (a) pore forming, (b) enzymatic degradation of membrane lipids, and (c) solubilizing cell membrane by a detergentlike action (4). Several hemolytic toxic proteins isolated...

show abstract

Section: Discussionmentioning

confidence: 78%

Functional Domains of a Pore-forming Cardiotoxic Protein, Volvatoxin A2

Weng

Lin

Hsu

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Although multiple past studies focused on understanding the implications of ATP-controlled signaling with respect to endogenous transmembrane transporters such as ion channels [17,19,20,24,[28][29][30][31], there is a recent interest in understanding how ATP controls the lytic action of pore-forming toxins (PFTs) [22,26,27,[32][33][34]. PFTs introduce unregulated conducting pathways into the host cell plasmalemma [35][36][37][38][39], which is expected to yield direct cytolysis. However, the generalization of direct cytolytic activity might be an oversimplification of the lytic mechanism employed by the PFTs.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, inhibition of cell lysis in the presence of ATP receptor antagonists demonstrated that a purinergic signaling pathway is responsible for the cell damage [26]. Nonetheless, many PFTs have a high potential to affect biological functions simply by introducing large conductance pathways within the cell membrane, thus dissipating the electrochemical gradients, which may cause serious damage and even cell death [37,38,40].…”

Section: Introductionmentioning

confidence: 99%

Purinergic control of lysenin’s transport and voltage-gating properties

Bryant

Shrestha

Carnig

et al. 2016

Purinergic Signalling

View full text Add to dashboard Cite

Lysenin, a pore-forming protein extracted from the coelomic fluid of the earthworm Eisenia foetida, manifests cytolytic activity by inserting large conductance pores in host membranes containing sphingomyelin. In the present study, we found that adenosine phosphates control the biological activity of lysenin channels inserted into planar lipid membranes with respect to their macroscopic conductance and voltage-induced gating. Addition of ATP, ADP, or AMP decreased the macroscopic conductance of lysenin channels in a concentration-dependent manner, with ATP being the most potent inhibitor and AMP the least. ATP removal from the bulk solutions by buffer exchange quickly reinstated the macroscopic conductance and demonstrated reversibility. Singlechannel experiments pointed to an inhibition mechanism that most probably relies on electrostatic binding and partial occlusion of the channel-conducting pathway, rather than ligand gating induced by the highly charged phosphates. The Hill analysis of the changes in macroscopic conduction as a function of the inhibitor concentration suggested cooperative binding as descriptive of the inhibition process. Ionic screening significantly reduced the ATP inhibitory efficacy, in support of the electrostatic binding hypothesis. In addition to conductance modulation, purinergic control over the biological activity of lysenin channels has also been observed to manifest as changes of the voltage-induced gating profile. Our analysis strongly suggests that not only the inhibitor's charge but also its ability to adopt a folded conformation may explain the differences in the observed influence of ATP, ADP, and AMP on lysenin's biological activity.

show abstract

“…7 For example, antibiotics such as Gramicidin insert into the membrane and allow sodium ions to enter which eventually leads to cell lysis. 8 A particularly vicious example, from the human perspective, is the toxin α-hemolysin (α-HL) from Staphylococcus aureus which is a common member of the bacterial community found on the skin.…”

mentioning

confidence: 99%