SIX2_LEIHE
ID SIX2_LEIHE Reviewed; 85 AA.
AC Q26292;
DT 26-SEP-2003, integrated into UniProtKB/Swiss-Prot.
DT 01-NOV-1996, sequence version 1.
DT 03-AUG-2022, entry version 98.
DE RecName: Full=Beta-insect depressant toxin LqhIT2;
DE Short=Insect toxin 2;
DE Short=Lqh IT2;
DE AltName: Full=LqhIT2-44;
DE Flags: Precursor;
OS Leiurus hebraeus (Deathstalker scorpion) (Leiurus quinquestriatus
OS hebraeus).
OC Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC Scorpiones; Buthida; Buthoidea; Buthidae; Leiurus.
OX NCBI_TaxID=6884;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA].
RX PubMed=8431601; DOI=10.1002/arch.940220107;
RA Zlotkin E., Gurevitz M., Fowler E., Adams M.E.;
RT "Depressant insect selective neurotoxins from scorpion venom: chemistry,
RT action, and gene cloning.";
RL Arch. Insect Biochem. Physiol. 22:55-73(1993).
RN [2]
RP PROTEIN SEQUENCE OF 22-82, AND AMIDATION AT GLY-82.
RC TISSUE=Venom;
RX PubMed=2029523; DOI=10.1021/bi00233a025;
RA Zlotkin E., Eitan M., Bindokas V.P., Adams M.E., Moyer M., Burkhart W.,
RA Fowler E.;
RT "Functional duality and structural uniqueness of depressant insect-
RT selective neurotoxins.";
RL Biochemistry 30:4814-4821(1991).
RN [3]
RP FUNCTION.
RX PubMed=9275012; DOI=10.1016/s0024-3205(97)00564-x;
RA Benkhalifa R., Stankiewicz M., Lapied B., Turkov M., Zilberberg N.,
RA Gurevitz M., Pelhate M.;
RT "Refined electrophysiological analysis suggests that a depressant toxin is
RT a sodium channel opener rather than a blocker.";
RL Life Sci. 61:819-830(1997).
RN [4]
RP MUTAGENESIS OF ASN-79.
RX PubMed=15966742; DOI=10.1021/bi050235t;
RA Strugatsky D., Zilberberg N., Stankiewicz M., Ilan N., Turkov M., Cohen L.,
RA Pelhate M., Gilles N., Gordon D., Gurevitz M.;
RT "Genetic polymorphism and expression of a highly potent scorpion depressant
RT toxin enable refinement of the effects on insect Na channels and illuminate
RT the key role of Asn-58.";
RL Biochemistry 44:9179-9187(2005).
RN [5]
RP IDENTIFICATION BY MASS SPECTROMETRY.
RX PubMed=16551474; DOI=10.1016/j.toxicon.2006.01.015;
RA Nascimento D.G., Rates B., Santos D.M., Verano-Braga T., Barbosa-Silva A.,
RA Dutra A.A.A., Biondi I., Martin-Eauclaire M.-F., De Lima M.E.,
RA Pimenta A.M.C.;
RT "Moving pieces in a taxonomic puzzle: venom 2D-LC/MS and data clustering
RT analyses to infer phylogenetic relationships in some scorpions from the
RT Buthidae family (Scorpiones).";
RL Toxicon 47:628-639(2006).
RN [6]
RP X-RAY CRYSTALLOGRAPHY (1.2 ANGSTROMS) OF 22-82, DISULFIDE BOND, AND
RP MUTAGENESIS OF TYR-24; LYS-26; ARG-27; ARG-28; ASP-29; GLY-30; LYS-32;
RP VAL-33; ALA-34; LEU-36; ILE-37; GLY-38; ASN-39; GLU-40; GLY-41; ASP-43;
RP LYS-44; GLU-45; TYR-49; SER-52; TYR-53; TYR-55; TRP-57; TRP-59; GLU-66;
RP PRO-69; ASP-70; ASP-71; LYS-72; THR-73; TRP-74; LYS-75; GLU-77; THR-78;
RP ASN-79; THR-80 AND GLY-82.
RX PubMed=17166514; DOI=10.1016/j.jmb.2006.10.085;
RA Karbat I., Turkov M., Cohen L., Kahn R., Gordon D., Gurevitz M., Frolow F.;
RT "X-ray structure and mutagenesis of the scorpion depressant toxin LqhIT2
RT reveals key determinants crucial for activity and anti-insect
RT selectivity.";
RL J. Mol. Biol. 366:586-601(2007).
CC -!- FUNCTION: Depressant insect beta-toxins cause a transient contraction
CC paralysis followed by a slow flaccid paralysis. They bind voltage-
CC independently at site-4 of sodium channels (Nav) and shift the voltage
CC of activation toward more negative potentials thereby affecting sodium
CC channel activation and promoting spontaneous and repetitive firing.
CC This toxin is active only on insects. {ECO:0000269|PubMed:9275012}.
CC -!- SUBCELLULAR LOCATION: Secreted.
CC -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to
CC antiparallel beta-sheets by disulfide bonds (CS-alpha/beta).
CC {ECO:0000305}.
CC -!- SIMILARITY: Belongs to the long (4 C-C) scorpion toxin superfamily.
CC Sodium channel inhibitor family. Beta subfamily. {ECO:0000305}.
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DR EMBL; S55538; AAB25386.1; -; mRNA.
DR PIR; A61616; A61616.
DR PDB; 2I61; X-ray; 1.20 A; A=22-82.
DR PDBsum; 2I61; -.
DR AlphaFoldDB; Q26292; -.
DR SMR; Q26292; -.
DR EvolutionaryTrace; Q26292; -.
DR GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR GO; GO:0019871; F:sodium channel inhibitor activity; IEA:InterPro.
DR GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR GO; GO:0006952; P:defense response; IEA:InterPro.
DR CDD; cd00107; Knot1; 1.
DR Gene3D; 3.30.30.10; -; 1.
DR InterPro; IPR044062; LCN-type_CS_alpha_beta_dom.
DR InterPro; IPR003614; Scorpion_toxin-like.
DR InterPro; IPR036574; Scorpion_toxin-like_sf.
DR InterPro; IPR018218; Scorpion_toxinL.
DR InterPro; IPR002061; Scorpion_toxinL/defensin.
DR Pfam; PF00537; Toxin_3; 1.
DR PRINTS; PR00285; SCORPNTOXIN.
DR SMART; SM00505; Knot1; 1.
DR SUPFAM; SSF57095; SSF57095; 1.
DR PROSITE; PS51863; LCN_CSAB; 1.
PE 1: Evidence at protein level;
KW 3D-structure; Amidation; Direct protein sequencing; Disulfide bond;
KW Ion channel impairing toxin; Neurotoxin; Secreted; Signal; Toxin;
KW Voltage-gated sodium channel impairing toxin.
FT SIGNAL 1..21
FT /evidence="ECO:0000269|PubMed:2029523"
FT CHAIN 22..82
FT /note="Beta-insect depressant toxin LqhIT2"
FT /id="PRO_0000035193"
FT DOMAIN 22..82
FT /note="LCN-type CS-alpha/beta"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01210"
FT SITE 16
FT /note="Forms a hot-spot in the bioactive surface"
FT SITE 24
FT /note="Forms a hot-spot in the bioactive surface"
FT SITE 28
FT /note="Forms a hot-spot in the bioactive surface"
FT MOD_RES 82
FT /note="Glycine amide"
FT /evidence="ECO:0000269|PubMed:2029523"
FT DISULFID 31..81
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT ECO:0000269|PubMed:17166514, ECO:0000312|PDB:2I61"
FT DISULFID 35..56
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT ECO:0000269|PubMed:17166514, ECO:0000312|PDB:2I61"
FT DISULFID 42..63
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT ECO:0000269|PubMed:17166514, ECO:0000312|PDB:2I61"
FT DISULFID 46..65
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01210,
FT ECO:0000269|PubMed:17166514, ECO:0000312|PDB:2I61"
FT MUTAGEN 24
FT /note="Y->F: 21-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 26
FT /note="K->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 27
FT /note="R->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 28
FT /note="R->D: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 29
FT /note="D->A: 22-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 30
FT /note="G->N: 55-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 32
FT /note="K->A: 240-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 32
FT /note="K->R: 25-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 32
FT /note="K->T: 122-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 33
FT /note="V->R: 50-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 33
FT /note="V->W: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 34
FT /note="A->E,R: 60-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 34
FT /note="A->S: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 34
FT /note="A->W: No significant increase in binding affinity to
FT cockroach sodium channels, but significant increase of
FT ability to shift the voltage dependence of activation in
FT Drosophila sodium channel DmNav1 (para)."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 36
FT /note="L->A: 24-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 37
FT /note="I->A: 700-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 38
FT /note="G->A: 33-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 39
FT /note="N->A: 35-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 40
FT /note="E->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 41
FT /note="G->A: 61-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 43
FT /note="D->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 44
FT /note="K->A: 600-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 45
FT /note="E->A: 119-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 45
FT /note="E->R: 460-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 49
FT /note="Y->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 49
FT /note="Y->W: 27-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 52
FT /note="S->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 53
FT /note="Y->V: 72-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 55
FT /note="Y->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 57
FT /note="W->A: 250-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 59
FT /note="W->A: 250-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 66
FT /note="E->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 69
FT /note="P->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 70
FT /note="D->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 71
FT /note="D->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 72
FT /note="K->D: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 73
FT /note="T->W: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 74
FT /note="W->V: 650-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 75
FT /note="K->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 77
FT /note="E->G: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 78
FT /note="T->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 79
FT /note="N->A: 110-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:15966742,
FT ECO:0000269|PubMed:17166514"
FT MUTAGEN 79
FT /note="N->D: 950-fold decrease in binding affinity to
FT cockroach sodium channels, and important loss of paralytic
FT activity against Sarcophaga larvae."
FT /evidence="ECO:0000269|PubMed:15966742,
FT ECO:0000269|PubMed:17166514"
FT MUTAGEN 79
FT /note="N->G: 590-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:15966742,
FT ECO:0000269|PubMed:17166514"
FT MUTAGEN 79
FT /note="N->Q: 99-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:15966742,
FT ECO:0000269|PubMed:17166514"
FT MUTAGEN 79
FT /note="N->S: 24.4-fold decrease in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:15966742,
FT ECO:0000269|PubMed:17166514"
FT MUTAGEN 80
FT /note="T->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT MUTAGEN 82
FT /note="G->A: No significant change in binding affinity to
FT cockroach sodium channels."
FT /evidence="ECO:0000269|PubMed:17166514"
FT HELIX 39..48
FT /evidence="ECO:0007829|PDB:2I61"
FT STRAND 52..55
FT /evidence="ECO:0007829|PDB:2I61"
FT STRAND 64..67
FT /evidence="ECO:0007829|PDB:2I61"
FT HELIX 70..72
FT /evidence="ECO:0007829|PDB:2I61"
FT HELIX 76..78
FT /evidence="ECO:0007829|PDB:2I61"
SQ SEQUENCE 85 AA; 9334 MW; CFCE3BB0A7079297 CRC64;
MKLLLLLIVS ASMLIESLVN ADGYIKRRDG CKVACLIGNE GCDKECKAYG GSYGYCWTWG
LACWCEGLPD DKTWKSETNT CGGKK
