Isolation of a New Cardiotoxic Protein from the Edible Mushroom, Volvariella volvacea

Lin, Jung‐Yaw; Jeng, Tzyy‐Wen; Chen, Cheng‐Chung; Shi, Guey‐Yueh; Tung, Ta‐Cheng

doi:10.1038/246524a0

Cited by 40 publications

(26 citation statements)

References 7 publications

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“…1OOg of mushroom was blended with 100mL distilled water for 5 min. The homogenate was boiled for 1 h. Lin (1973) reported that volvatoxin was present in the straw mushroom which caused ventricular systolic arrest in tested animals. The toxicity of volvatoxin was, however, eliminated by heating at 100 "C for 20 min.…”

Section: Methodsmentioning

confidence: 99%

Cardiovascular active substances from the straw mushroom, Volvariella volvacea

Chiu

Lam

Pang

1995

Phytotherapy Research

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The straw mushroom Volvuriellu volvuceu is one of the common edible mushrooms in Hong Kong and is widely cultivated in Southeast Asian countries. It has been reported to produce a hypotensive response in animals including humans. An aqueous extract of the mushroom (SME) was prepared and given through intravenous injections to normotensive rats. The blood pressure changes produced by SME alone or in the presence of various drugs were studied. The effects of SME on the kidney function of water-loaded rats and on isolated tissue preparations of the tail artery and right atrium were examined. An i.v. injection of SME produced a hypotensive effect in rats with an ED,of 25 mg dry weightlkg body weight. This hypotensive effect of SME was attenuated or blunted in the presence of hexamethonium, phentolamine, pyrilamine and cimetidine suggesting the involvement of the a-adrenergic component of the autonomic system and/or histamineergic stimulation. SME did not increase urinary excretion nor sodium diuresis. It produced positive chronotropic and inotropic effects on isolated right atria and induced contraction of isolated tail artery strips. This latter contractile response was inhibited by antagonists of serotonin and a-adrenoceptor, ketanserin and phentolamine respectively. Partial purification using dialysis and liquid chromatography revealed that the hypotensive active substances had molecular masses between 8000 and 12000 dalton. These substances were heat stable and resistant to trypsin digestion. In view of the similarity in blood pressure and cardiovascular response, SME might contain serotonin-like substances.

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Section: Methodsmentioning

confidence: 99%

Cardiovascular active substances from the straw mushroom, Volvariella volvacea

Chiu

Lam

Pang

1995

Phytotherapy Research

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“…The Rapid Translation System RTS 500 Escherichia coli circular template kit and complete protease inhibitor mixture were from Roche Applied Science. VVA2 was isolated from the fruit body of Volvariella volvacea, grass mushrooms, as described previously (1). All other chemicals were of analytical grade.…”

Section: Methodsmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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

Weng

Lin

Hsu

et al. 2004

Journal of Biological Chemistry

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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...

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“…VVA2 consist of 199 amino acids and possesses hemolytic and cytolytic properties. 27,28,35 The main difference between the structure of VVA2 and that of Cyt2Ba is an insertion of a β- hairpin between α1 and α2 in VVA2 (indicated by an arrow in Fig. 4b).…”

Section: Comparison Of Cyt2ba With Structurally Related Proteinsmentioning

confidence: 98%