Summary: Sea anemone cytotoxic protein
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Sea anemone cytotoxic protein Edit Wikipedia article
|crystal structure of the water-soluble state of the pore-forming cytolysin sticholysin ii complexed with phosphorylcholine|
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. 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. The crystal structures of equinotoxin II  and sticholysin II  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.
- Anderluh G, Macek P (February 2002). "Cytolytic peptide and protein toxins from sea anemones (Anthozoa: Actiniaria)". Toxicon 40 (2): 11124. doi:10.1016/S0041-0101(01)00191-X. PMID 11689232.
- Anderluh G, Macek P (November 2003). "Dissecting the actinoporin pore-forming mechanism". Structure 11 (11): 13123. doi:10.1016/j.str.2003.10.007. PMID 14604518.
- 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): 121929. doi:10.1006/jmbi.2001.5321. PMID 11827489.
- 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): 131928. doi:10.1016/j.str.2003.09.019. PMID 14604522.
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 .
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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|Cellular component||pore complex (GO:0046930)|
|Molecular function||channel activity (GO:0015267)|
|Biological process||pore complex assembly (GO:0046931)|
|hemolysis in other organism involved in symbiotic interaction (GO:0052331)|
|cation transport (GO:0006812)|
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|Seed source:||Pfam-B_14701 (release 9.0)|
|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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build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||7|
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