{PDOC60021}
{PS60021; HWTX_1}
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* Huwentoxin-1 family signature *
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The spider  venoms  often  contain  many  active peptides such as neurotoxins,
lectins, inhibitors  to  enzyme,  etc.  These  peptides are very important for
spider's hunting  and  defending. During the long history of spider evolution,
the peptides  evolved  into  different structures and functions. Despite their
different biological  functions  the following peptides appear to have evolved
from the same ancestors and belong to the huwentoxin-1 family [1]:

 - Ornithoctonus   huwena   (Chinese   bird   spider)   (Selenocosmia  huwena)
   huwentoxin-I (HWTX-I),  a 33 amino acid peptide, which can block the N-type
   high-voltage activated calcium channels [2].
 - Ornithoctonus   huwena   (Chinese   bird   spider)   (Selenocosmia  huwena)
   huwentoxin-IIIa (HWTX-IIIa).
 - Ornithoctonus   huwena   (Chinese   bird   spider)   (Selenocosmia  huwena)
   huwentoxin-IV (HWTX-IV),  a 35 amino acid peptide, which is an inhibitor of
   tetrodotoxin (TTX) sensitive voltage-gated sodium channel [3].
 - Ornithoctonus   huwena   (Chinese   bird   spider)   (Selenocosmia  huwena)
   huwentoxin-V (HWTX-V),  a  35  amino  acid  insecticidal  toxin  which  can
   reversibly paralyze in insects [4].
 - Ornithoctonus   huwena   (Chinese   bird   spider)   (Selenocosmia  huwena)
   huwenlectin-I (SHL-I),  a  32  amino  acid  peptide  with haemagglutination
   activity but almost no neurotoxin activity.
 - Selenocosmia  hainana  Hainantoxin-I  (HNTX-I), Hainantoxin-III (HNTX-III),
   Hainantoxin-IV (HNTX-IV) and Hainantoxin-V (HNTX-V) [5].
 - Brachypelma smithii (Mexican red knee tarantula) Venom protein 5.
 - Grammostola spatulata (Chilean rose tarantula) voltage sensor toxin 1.

Peptides of  the huwentoxin type I family contain 6 cysteine residues involved
in three  disulfide  bonds.  The three disulfide bridges have been assigned as
C1-C4, C2-C5  and  C3-C6.  HWTX-I  adopts  a compact structure consisting of a
small triple-stranded   antiparallel   beta-sheet  and  five  beta-turns  (see
<PDB:1QK6>) [6].

We developed  a  pattern  for  huwentoxin-1  family  proteins,  which  have  a
[C-C-CC-C-C] cysteine   arrangement.   The   three-dimensional   structure  of
huwentoxin-1 family proteins possess a knottin scafold (see <PDOC60004>) [E1].

-Conserved pattern: C-[KALRVG]-x-{M}-X(1,3)-C-x(4,6)-C-C-x(4,6)-C-x(4)-[ERK]-
                    W-C
                    [The 6 C's are involved in disulfide bonds]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 O. huwena  toxin-1  since  the sixth conserved cysteine (expected to complete
 the knottin scaffold) is missing.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Expert(s) to contact by email:
           Ramakumar S.; ramak@physics.iisc.ernet.in

-Last update: August 2005 / First entry.

[ 1] Diao J., Lin Y., Tang J., Liang S.-P.
     "cDNA sequence analysis of seven peptide toxins from the spider
     Selenocosmia huwena."
     Toxicon 42:715-723(2003).
     PubMed=14757201
[ 2] Liang S.-P., Zhang D.Y., Pan X., Chen Q., Zhou P.A.
     "Properties and amino acid sequence of huwentoxin-I, a neurotoxin
     purified from the venom of the Chinese bird spider Selenocosmia
     huwena."
     Toxicon 31:969-978(1993).
     PubMed=8212049
[ 3] Liu Z., Dai J., Chen Z., Hu W., Xiao Y., Liang S.-P.
     "Isolation and characterization of hainantoxin-IV, a novel antagonist
     of tetrodotoxin-sensitive sodium channels from the Chinese bird spider
     Selenocosmia hainana."
     Cell. Mol. Life Sci. 60:972-978(2003).
     PubMed=12827284; DOI=10.1007/s00018-003-2354-x
[ 4] Zhang P.F., Chen P., Hu W.-J., Liang S.-P.
     "Huwentoxin-V, a novel insecticidal peptide toxin from the spider
     Selenocosmia huwena, and a natural mutant of the toxin: indicates the
     key amino acid residues related to the biological activity."
     Toxicon 42:15-20(2003).
     PubMed=12893056
[ 5] Xiao Y.-C., Liang S.-P.
     "Purification and characterization of Hainantoxin-V, a
     tetrodotoxin-sensitive sodium channel inhibitor from the venom of the
     spider Selenocosmia hainana."
     Toxicon 41:643-650(2003).
     PubMed=12727268
[ 6] Qu Y., Liang S., Ding J., Liu X., Zhang R., Gu X.
     "Proton nuclear magnetic resonance studies on huwentoxin-I from the
     venom of the spider Selenocosmia huwena: 2. Three-dimensional
     structure in solution."
     J. Protein Chem. 16:565-574(1997).
     PubMed=9263120
[E1] https://bioserv.cbs.cnrs.fr

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