ID   VIRTX_AMAVR             Reviewed;           7 AA.
AC   P85363;
DT   05-FEB-2008, integrated into UniProtKB/Swiss-Prot.
DT   05-FEB-2008, sequence version 1.
DT   22-APR-2020, entry version 14.
DE   RecName: Full=Virotoxin;
DE   AltName: Full=Viroidin;
DE   AltName: Full=Viroisin;
OS   Amanita virosa (European destroying angel) (Agaricus virosa).
OC   Eukaryota; Fungi; Dikarya; Basidiomycota; Agaricomycotina; Agaricomycetes;
OC   Agaricomycetidae; Agaricales; Amanitaceae; Amanita.
OX   NCBI_TaxID=78357;
RN   [1] {ECO:0000305}
RP   PROTEIN SEQUENCE, FUNCTION, METHYLATION AT TRP-2, HYDROXYLATION AT LEU-3,
RP   D-AMINO ACID AT THR-5 AND CYS-6, HYDROXYLATION AT PRO-7, AND TOXIC DOSE.
RX   PubMed=6893271; DOI=10.1021/bi00555a036;
RA   Faulstich H., Buku A., Bodenmueller H., Wieland T.;
RT   "Virotoxins: actin-binding cyclic peptides of Amanita virosa mushrooms.";
RL   Biochemistry 19:3334-3343(1980).
CC   -!- FUNCTION: A toxin that binds to rabbit muscle actin with a dissociation
CC       constant of 20 nM preventing actin depolymerization, causing cellular
CC       and tissue disruption, and death. {ECO:0000269|PubMed:6893271}.
CC   -!- PTM: The 2'-methylsulfonyltryptophan is thought to arise from cross-
CC       linking to Cys-6, as found in other Amanita peptide toxins, followed by
CC       sulfur methylation, beta-elimination, and oxidation. The cysteine,
CC       converted to 2,3-didehydroalanine, is hydrated to D-serine.
CC       {ECO:0000269|PubMed:6893271}.
CC   -!- TOXIC DOSE: LD(50) is 2.5 mg/kg by intraperitoneal injection into mice.
CC       {ECO:0000269|PubMed:6893271}.
CC   -!- CAUTION: This peptide is cyclic. {ECO:0000305}.
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DR   PIR; A58725; A58725.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   D-amino acid; Direct protein sequencing; Hydroxylation; Methylation; Toxin.
FT   PEPTIDE         1..7
FT                   /note="Virotoxin"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT                   /id="PRO_0000316857"
FT   MOD_RES         2
FT                   /note="2'-methylsulfonyltryptophan"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   MOD_RES         3
FT                   /note="(4R)-4,5-dihydroxyleucine; in form viroidin"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   MOD_RES         3
FT                   /note="4,5,5'-trihydroxyleucine; in form viroisin"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   MOD_RES         5
FT                   /note="D-threonine"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   MOD_RES         6
FT                   /note="D-serine (Cys)"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   MOD_RES         7
FT                   /note="(3R,4R)-3,4-dihydroxyproline"
FT                   /evidence="ECO:0000269|PubMed:6893271"
FT   CROSSLNK        1..7
FT                   /note="Cyclopeptide (Ala-Pro)"
FT                   /evidence="ECO:0000269|PubMed:6893271"
SQ   SEQUENCE   7 AA;  789 MW;  776EA1B2C7337DB0 CRC64;
     AWLVTCP