ACTPA_ACTFR
ID ACTPA_ACTFR Reviewed; 20 AA.
AC P0DUW8;
DT 29-SEP-2021, integrated into UniProtKB/Swiss-Prot.
DT 29-SEP-2021, sequence version 1.
DT 25-MAY-2022, entry version 3.
DE RecName: Full=DELTA-actitoxin-Afr1b {ECO:0000305};
DE Short=DELTA-AITX-Afr1b {ECO:0000305};
DE AltName: Full=Alpha-helical pore-forming toxin {ECO:0000250|UniProtKB:B9W5G6};
DE Short=PFT {ECO:0000250|UniProtKB:B9W5G6};
DE AltName: Full=Cytolysin {ECO:0000250|UniProtKB:B9W5G6};
DE AltName: Full=Fragaceatoxin A {ECO:0000303|PubMed:31295915};
DE Short=fraA {ECO:0000303|PubMed:31295915};
DE Flags: Fragment;
OS Actinia fragacea (Strawberry anemone).
OC Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC Actiniidae; Actinia.
OX NCBI_TaxID=396334;
RN [1]
RP PROTEIN SEQUENCE, FUNCTION, MASS SPECTROMETRY, AND BIOPHYSICOCHEMICAL
RP PROPERTIES.
RX PubMed=31295915; DOI=10.3390/toxins11070401;
RA Morante K., Bellomio A., Viguera A.R., Gonzalez-Manas J.M., Tsumoto K.,
RA Caaveiro J.M.M.;
RT "The isolation of new pore-forming toxins from the sea anemone Actinia
RT fragacea provides insights into the mechanisms of actinoporin evolution.";
RL Toxins 11:0-0(2019).
CC -!- FUNCTION: Pore-forming toxin (PFT) that consists of a crown-shaped
CC octamer or nonamer that forms cation-selective hydrophilic pores of
CC about 1.5 nm (inside) and 13 nm (outside) (By similarity). It causes
CC cardiac stimulation (By similarity). Also causes hemolysis (HC(50)=0.4
CC nM) (PubMed:31295915). Interestingly, the Phe-16 is crucial for
CC hemolysis (By similarity). Pore formation is a multi-step process that
CC involves specific recognition of membrane sphingomyelin (but neither
CC cholesterol nor phosphatidylcholine) using aromatic rich region and
CC adjacent phosphocholine (POC) binding site, firm binding to the
CC membrane (mainly driven by hydrophobic interactions) accompanied by the
CC transfer of the N-terminal region to the lipid-water interface and
CC finally pore formation after oligomerization of monomers (By
CC similarity). It is probable that a dimeric form is an assembly
CC intermediate before the complete oligomerization (By similarity). The
CC formation of stable pores occurs only in vesicles composed of DOPC/SM
CC (there is no oligomerization when the PFT is treated with vesicles of
CC DOPC or SM alone) (By similarity). The transmembrane pore displays 8
CC lateral perforations, one at each subunit-subunit interface, partially
CC occupied by the acyl-chain region of a bridging lipid (By similarity).
CC Each pore contains 24 lipid molecules, firmly bound to each subunit,
CC that is, 3 lipids (L1, L2, L3, L4 and/or L5) are associated to each
CC subunit (By similarity). Lipid L1 bridges 2 subunits, whereas lipids L2
CC and L3 bind to sites at single subunit (By similarity).
CC {ECO:0000250|UniProtKB:B9W5G6, ECO:0000269|PubMed:31295915}.
CC -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC Temperature dependence:
CC Stable up to about 65 degrees Celsius. {ECO:0000269|PubMed:31295915};
CC -!- SUBUNIT: Octamer or nonamer in membranes. Monomer in the soluble state.
CC {ECO:0000250|UniProtKB:B9W5G6}.
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:31295915}.
CC Nematocyst {ECO:0000250|UniProtKB:P61914}. Target cell membrane
CC {ECO:0000250|UniProtKB:B9W5G6}. Note=Forms an alpha-helical membrane
CC channel in the prey. {ECO:0000250|UniProtKB:B9W5G6}.
CC -!- DOMAIN: The N-terminal region, before the pore is formed, is bound to
CC the lipid membrane. It partitions into the lipid-water interface and
CC stabilizes the monomeric molecule on the membrane. Finally, it
CC traverses the bilayer, thus forming the transmembrane pore.
CC {ECO:0000250|UniProtKB:P61914}.
CC -!- MASS SPECTROMETRY: Mass=19728; Mass_error=3; Method=Electrospray;
CC Evidence={ECO:0000269|PubMed:31295915};
CC -!- MISCELLANEOUS: This protein has been found to bind carbohydrates, since
CC it shows a substantial delay in elution profile in size-exclusion
CC chromatography. The carbohydrate pocket ovelaps with the lipid-binding
CC module of actinoporins. {ECO:0000250|UniProtKB:B9W5G6}.
CC -!- SIMILARITY: Belongs to the actinoporin family. Sea anemone subfamily.
CC {ECO:0000305}.
CC ---------------------------------------------------------------------------
CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC ---------------------------------------------------------------------------
DR GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR GO; GO:0042151; C:nematocyst; IEA:UniProtKB-SubCell.
DR GO; GO:0008289; F:lipid binding; IEA:UniProtKB-KW.
DR GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR GO; GO:0044179; P:hemolysis in another organism; IEA:UniProtKB-KW.
DR GO; GO:0006811; P:ion transport; IEA:UniProtKB-KW.
PE 1: Evidence at protein level;
KW Cytolysis; Direct protein sequencing; Hemolysis; Ion transport;
KW Lipid-binding; Membrane; Nematocyst; Secreted; Target cell membrane;
KW Target membrane; Toxin; Transmembrane; Transport.
FT CHAIN 1..>20
FT /note="DELTA-actitoxin-Afr1b"
FT /evidence="ECO:0000269|PubMed:31295915"
FT /id="PRO_0000453822"
FT SITE 16
FT /note="Part of the hydrophobic cavity (in subunit A) that
FT receives Val-60 from the adjacent subunit (B); essential in
FT hemolysis, since it is critical for pore formation in
FT cholesterol-rich membrane cells (such as red blood cells)"
FT /evidence="ECO:0000250|UniProtKB:B9W5G6"
FT NON_TER 20
FT /evidence="ECO:0000305|PubMed:31295915"
SQ SEQUENCE 20 AA; 2017 MW; 3935C151509FF5E8 CRC64;
SAEVAGAVIE GAKLTFNVLQ
