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19  structures 24  species 1  interaction 46  sequences 1  architecture

Family: Anemone_cytotox (PF06369)

Summary: Sea anemone cytotoxic protein

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This is the Wikipedia entry entitled "Sea anemone cytotoxic protein". More...

Sea anemone cytotoxic protein Edit Wikipedia article

Anemone_cytotox
PDB 1o72 EBI.jpg
crystal structure of the water-soluble state of the pore-forming cytolysin sticholysin ii complexed with phosphorylcholine
Identifiers
Symbol Anemone_cytotox
Pfam PF06369
InterPro IPR009104
SCOP 1kd6
SUPERFAMILY 1kd6
TCDB 1.C.38
OPM superfamily 103
OPM protein 1iaz

In molecular biology, the sea anemone cytotoxic proteins are lethal pore-forming peptides and proteins, known collectively as cytolysins or actinoporins. There are several different groups of cytolysins based on their structure and function.[1] This entry represents the most numerous group, the 20kDa highly basic peptides. These cytolysins form cation-selective pores in sphingomyelin-containing membranes. Examples include equinatoxins (from Actinia equina), sticholysins (from Stichodactyla helianthus), magnificalysins (from Heteractis magnifica), and tenebrosins (from Actinia tenebrosa), which exhibit pore-forming, haemolytic, cytotoxic, and heart stimulatory activities.

Cytolysins adopt a stable soluble structure, which undergoes a conformational change when brought in contact with a membrane, leading to an active, membrane-bound form that inserts spontaneously into the membrane. They often oligomerise on the membrane surface, before puncturing the lipid bilayers, causing the cell to lyse. The 20kDa sea anemone cytolysins require a phosphocholine lipid headgroup for binding, however sphingomyelin is required for the toxin to promote membrane permeability.[2] The crystal structures of equinotoxin II [3] and sticholysin II [4] both revealed a compact beta-sandwich consisting of ten strands in two sheets flanked on each side by two short alpha-helices, which is a similar topology to osmotin. It is believed that the beta sandwich structure attaches to the membrane, while a three-turn alpha helix lying on the surface of the beta sheet may be involved in membrane pore formation, possibly by the penetration of the membrane by the helix.

References[edit]

  1. ^ Anderluh G, Macek P (February 2002). "Cytolytic peptide and protein toxins from sea anemones (Anthozoa: Actiniaria)". Toxicon 40 (2): 111–24. doi:10.1016/S0041-0101(01)00191-X. PMID 11689232. 
  2. ^ Anderluh G, Macek P (November 2003). "Dissecting the actinoporin pore-forming mechanism". Structure 11 (11): 1312–3. doi:10.1016/j.str.2003.10.007. PMID 14604518. 
  3. ^ Hinds MG, Zhang W, Anderluh G, Hansen PE, Norton RS (February 2002). "Solution structure of the eukaryotic pore-forming cytolysin equinatoxin II: implications for pore formation". J. Mol. Biol. 315 (5): 1219–29. doi:10.1006/jmbi.2001.5321. PMID 11827489. 
  4. ^ Mancheno JM, Martin-Benito J, Marti­nez-Ripoll M, Gavilanes JG, Hermoso JA (November 2003). "Crystal and electron microscopy structures of sticholysin II actinoporin reveal insights into the mechanism of membrane pore formation". Structure 11 (11): 1319–28. doi:10.1016/j.str.2003.09.019. PMID 14604522. 

This article incorporates text from the public domain Pfam and InterPro IPR009104

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Sea anemone cytotoxic protein Provide feedback

Sea anemones are a rich source of cytotoxic proteins. Cytolysins comprise a group of more than 30 highly basic proteins with molecular masses of about 20 kDa. Cytolysins isolated from the sea anemone, Heteractis magnifica, include magnificalysin I (HMg I), magnificalysin II (HMg II) and Heteractis magnifica toxin (HMgtxn). These are highly homologous at their N-terminals. HMg I and II have molecular masses of approximately 19 kDa, and pI values of 9.4 and 10.0, respectively. Cytolysins isolated from other sea anemones Actinia tenebrosa (Tenebrosin-C, TN-C), Actinia equina (Equinatoxin, EqT) and Stichodactyla helianthus (ShC) exhibit pore-forming, haemolytic, cytotoxic, and heart stimulatory activities [1].

Literature references

  1. Wang Y, Chua KL, Khoo HE; , Biochim Biophys Acta 2000;1478:9-18.: A new cytolysin from the sea anemone, Heteractis magnifica: isolation, cDNA cloning and functional expression. PUBMED:10719170 EPMC:10719170


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR009104

Sea anemones are a rich source of lethal pore-forming peptides and proteins, known collectively as cytolysins or actinoporins. There are several different groups of cytolysins based on their structure and function [PUBMED:11689232]. This entry represents the most numerous group, the 20kDa highly basic peptides. These cytolysins form cation-selective pores in sphingomyelin-containing membranes. Examples include equinatoxins (from Actinia equina), sticholysins (from Stichodactyla helianthus), magnificalysins (from Heteractis magnifica), and tenebrosins (from Actinia tenebrosa), which exhibit pore-forming, haemolytic, cytotoxic, and heart stimulatory activities.

Cytolysins adopt a stable soluble structure, which undergoes a conformational change when brought in contact with a membrane, leading to an active, membrane-bound form that inserts spontaneously into the membrane. They often oligomerise on the membrane surface, before puncturing the lipid bilayers, causing the cell to lyse. The 20kDa sea anemone cytolysins require a phosphocholine lipid headgroup for binding, however sphingomyelin is required for the toxin to promote membrane permeability [PUBMED:14604518]. The crystal structures of equinotoxin II [PUBMED:11827489] and sticholysin II [PUBMED:14604522] both revealed a compact beta-sandwich consisting of ten strands in two sheets flanked on each side by two short alpha-helices, which is a similar topology to osmotin. It is believed that the beta sandwich structure attaches to the membrane, while a three-turn alpha helix lying on the surface of the beta sheet may be involved in membrane pore formation, possibly by the penetration of the membrane by the helix.

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Representative proteomes NCBI
(55)
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RP35
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RP55
(17)
RP75
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Seed source: Pfam-B_14701 (release 9.0)
Previous IDs: none
Type: Family
Author: Moxon SJ
Number in seed: 3
Number in full: 46
Average length of the domain: 153.10 aa
Average identity of full alignment: 36 %
Average coverage of the sequence by the domain: 87.33 %

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search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 25.0 25.2
Noise cut-off 20.9 24.3
Model length: 176
Family (HMM) version: 7
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Anemone_cytotox

Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Anemone_cytotox domain has been found. There are 19 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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