A1H2_LOXRE
ID A1H2_LOXRE Reviewed; 305 AA.
AC P0CE79; Q5I225; Q5YD74;
DT 23-MAR-2010, integrated into UniProtKB/Swiss-Prot.
DT 23-MAR-2010, sequence version 1.
DT 03-AUG-2022, entry version 44.
DE RecName: Full=Dermonecrotic toxin LrSicTox-alphaIA1ii;
DE EC=4.6.1.- {ECO:0000250|UniProtKB:Q4ZFU2};
DE AltName: Full=Dermonecrotic toxin;
DE AltName: Full=Phospholipase D;
DE Short=PLD;
DE AltName: Full=SMaseD/LysoPLD;
DE AltName: Full=Sphingomyelin phosphodiesterase D;
DE Short=SMD;
DE Short=SMase D;
DE Short=Sphingomyelinase D;
DE Flags: Precursor;
OS Loxosceles reclusa (Brown recluse spider).
OC Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC Araneomorphae; Haplogynae; Scytodoidea; Sicariidae; Loxosceles.
OX NCBI_TaxID=6921;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, CATALYTIC ACTIVITY, ACTIVITY
RP REGULATION, BIOPHYSICOCHEMICAL PROPERTIES, MUTAGENESIS OF HIS-37; HIS-73;
RP HIS-108; HIS-164; HIS-180 AND THR-258, AND SUBSTRATE SPECIFICITY.
RC TISSUE=Venom gland;
RX PubMed=15926888; DOI=10.1042/bj20050043;
RA Lee S., Lynch K.R.;
RT "Brown recluse spider (Loxosceles reclusa) venom phospholipase D (PLD)
RT generates lysophosphatidic acid (LPA).";
RL Biochem. J. 391:317-323(2005).
CC -!- FUNCTION: Dermonecrotic toxins cleave the phosphodiester linkage
CC between the phosphate and headgroup of certain phospholipids
CC (sphingolipid and lysolipid substrates), forming an alcohol (often
CC choline) and a cyclic phosphate (By similarity). This toxin acts on
CC sphingomyelin (SM) (PubMed:15926888). It also acts on a broad range of
CC lysophospholipids, like lysophosphatidylinositol (LPI),
CC lysophosphatidylglycerol (LPG), lysophosphatidylethanolamine (LPE),
CC lysobisphosphatidic acid (LBPA), lysophosphatidylserine (LPS) and
CC lysophosphatidylcholines (LPC) of varying chain lengths
CC (PubMed:15926888). The substrate preference is LPI > LPG > LPS > LPC >>
CC LPE, LBPA (PubMed:15926888). Furthermore, the enzyme also act on cyclic
CC phosphatidic acid and lyso-platelet activating factor (LPAF, an alkyl-
CC LPC) (PubMed:15926888). The enzyme does not act on
CC sphingosylphosphorylcholine (SPC, also known as lyso-sphingomyelin) and
CC PAF (PubMed:15926888). The toxin may also act on ceramide
CC phosphoethanolamine (CPE) (By similarity). It acts by
CC transphosphatidylation, releasing exclusively cyclic phosphate products
CC as second products (By similarity). It does not exhibit detectable
CC PLA1/2 activity (PubMed:15926888). It induces dose-dependent hemolysis
CC and dermonecrosis (PubMed:15926888). Also induces increased vascular
CC permeability, edema, inflammatory response, and platelet aggregation
CC (By similarity). {ECO:0000250|UniProtKB:A0A0D4WTV1,
CC ECO:0000250|UniProtKB:P0CE80, ECO:0000269|PubMed:15926888}.
CC -!- CATALYTIC ACTIVITY:
CC Reaction=an N-(acyl)-sphingosylphosphocholine = an N-(acyl)-sphingosyl-
CC 1,3-cyclic phosphate + choline; Xref=Rhea:RHEA:60652,
CC ChEBI:CHEBI:15354, ChEBI:CHEBI:64583, ChEBI:CHEBI:143892;
CC Evidence={ECO:0000305|PubMed:15926888};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=an N-(acyl)-sphingosylphosphoethanolamine = an N-(acyl)-
CC sphingosyl-1,3-cyclic phosphate + ethanolamine; Xref=Rhea:RHEA:60648,
CC ChEBI:CHEBI:57603, ChEBI:CHEBI:143891, ChEBI:CHEBI:143892;
CC Evidence={ECO:0000250|UniProtKB:A0A0D4WTV1};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=a 1-acyl-sn-glycero-3-phosphocholine = a 1-acyl-sn-glycero-
CC 2,3-cyclic phosphate + choline; Xref=Rhea:RHEA:60700,
CC ChEBI:CHEBI:15354, ChEBI:CHEBI:58168, ChEBI:CHEBI:143947;
CC Evidence={ECO:0000305|PubMed:15926888};
CC -!- CATALYTIC ACTIVITY:
CC Reaction=a 1-acyl-sn-glycero-3-phosphoethanolamine = a 1-acyl-sn-
CC glycero-2,3-cyclic phosphate + ethanolamine; Xref=Rhea:RHEA:60704,
CC ChEBI:CHEBI:57603, ChEBI:CHEBI:64381, ChEBI:CHEBI:143947;
CC Evidence={ECO:0000305|PubMed:15926888};
CC -!- COFACTOR:
CC Name=Mg(2+); Xref=ChEBI:CHEBI:18420;
CC Evidence={ECO:0000250|UniProtKB:Q8I914};
CC Note=Binds 1 Mg(2+) ion per subunit. {ECO:0000250|UniProtKB:Q8I914};
CC -!- ACTIVITY REGULATION: Inhibited with low affinity by edelfosine.
CC {ECO:0000269|PubMed:15926888}.
CC -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC Kinetic parameters:
CC KM=436 uM for LPC (12:0) {ECO:0000269|PubMed:15926888};
CC KM=219 uM for LPC (14:0) {ECO:0000269|PubMed:15926888};
CC KM=220 uM for LPC (16:0) {ECO:0000269|PubMed:15926888};
CC KM=104 uM for LPC (18:0) {ECO:0000269|PubMed:15926888};
CC KM=98 uM for LPC (18:1) {ECO:0000269|PubMed:15926888};
CC KM=56 uM for LPAF {ECO:0000269|PubMed:15926888};
CC KM=396 uM for sphingomyelin {ECO:0000269|PubMed:15926888};
CC Vmax=0.47 umol/min/mg enzyme toward LPC (12:0)
CC {ECO:0000269|PubMed:15926888};
CC Vmax=2.97 umol/min/mg enzyme toward LPC (14:0)
CC {ECO:0000269|PubMed:15926888};
CC Vmax=1.18 umol/min/mg enzyme toward LPC (16:0)
CC {ECO:0000269|PubMed:15926888};
CC Vmax=2.37 umol/min/mg enzyme toward LPC (18:0)
CC {ECO:0000269|PubMed:15926888};
CC Vmax=2.62 umol/min/mg enzyme toward LPC (18:1)
CC {ECO:0000269|PubMed:15926888};
CC Vmax=1.00 umol/min/mg enzyme toward LPAF
CC {ECO:0000269|PubMed:15926888};
CC Vmax=2.95 umol/min/mg enzyme toward sphingomyelin
CC {ECO:0000269|PubMed:15926888};
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305|PubMed:15926888}.
CC -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC {ECO:0000305|PubMed:15926888}.
CC -!- SIMILARITY: Belongs to the arthropod phospholipase D family. Class II
CC subfamily. Class IIa sub-subfamily. {ECO:0000305}.
CC -!- CAUTION: The most common activity assay for dermonecrotic toxins
CC detects enzymatic activity by monitoring choline release from
CC substrate. Liberation of choline from sphingomyelin (SM) or
CC lysophosphatidylcholine (LPC) is commonly assumed to result from
CC substrate hydrolysis, giving either ceramide-1-phosphate (C1P) or
CC lysophosphatidic acid (LPA), respectively, as a second product.
CC However, two studies from Lajoie and colleagues (2013 and 2015) report
CC the observation of exclusive formation of cyclic phosphate products as
CC second products, resulting from intramolecular transphosphatidylation.
CC Cyclic phosphates have vastly different biological properties from
CC their monoester counterparts, and they may be relevant to the pathology
CC of brown spider envenomation. {ECO:0000250|UniProtKB:A0A0D4WTV1,
CC ECO:0000250|UniProtKB:A0A0D4WV12, ECO:0000250|UniProtKB:Q4ZFU2}.
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DR EMBL; AY862486; AAW56831.1; -; mRNA.
DR AlphaFoldDB; P0CE79; -.
DR SMR; P0CE79; -.
DR GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR GO; GO:0016829; F:lyase activity; IEA:UniProtKB-KW.
DR GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR GO; GO:0008081; F:phosphoric diester hydrolase activity; IEA:InterPro.
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:0016042; P:lipid catabolic process; IEA:UniProtKB-KW.
DR Gene3D; 3.20.20.190; -; 1.
DR InterPro; IPR017946; PLC-like_Pdiesterase_TIM-brl.
DR SUPFAM; SSF51695; SSF51695; 1.
PE 1: Evidence at protein level;
KW Cytolysis; Dermonecrotic toxin; Disulfide bond; Glycoprotein; Hemolysis;
KW Lipid degradation; Lipid metabolism; Lyase; Magnesium; Metal-binding;
KW Secreted; Signal; Toxin; Zymogen.
FT SIGNAL 1..18
FT /evidence="ECO:0000255"
FT PROPEP 19..26
FT /evidence="ECO:0000250"
FT /id="PRO_0000392733"
FT CHAIN 27..305
FT /note="Dermonecrotic toxin LrSicTox-alphaIA1ii"
FT /id="PRO_0000392734"
FT ACT_SITE 37
FT /evidence="ECO:0000269|PubMed:15926888"
FT ACT_SITE 73
FT /note="Nucleophile"
FT /evidence="ECO:0000269|PubMed:15926888"
FT BINDING 57
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250|UniProtKB:Q8I914"
FT BINDING 59
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250|UniProtKB:Q8I914"
FT BINDING 117
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250|UniProtKB:Q8I914"
FT CARBOHYD 282
FT /note="N-linked (GlcNAc...) asparagine"
FT /evidence="ECO:0000255"
FT DISULFID 77..83
FT /evidence="ECO:0000250|UniProtKB:P0CE80"
FT DISULFID 79..222
FT /evidence="ECO:0000250|UniProtKB:P0CE80"
FT MUTAGEN 37
FT /note="H->N: Abolishes enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
FT MUTAGEN 73
FT /note="H->N: Abolishes enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
FT MUTAGEN 108
FT /note="H->A,N: Little decrease in enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
FT MUTAGEN 164
FT /note="H->N: Little decrease in enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
FT MUTAGEN 180
FT /note="H->N: Little decrease in enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
FT MUTAGEN 258
FT /note="T->V: Little decrease in enzyme activity."
FT /evidence="ECO:0000269|PubMed:15926888"
SQ SEQUENCE 305 AA; 34218 MW; 235000E0E7E48CBA CRC64;
MLLYVTLILG CWSAFSESAE TDVAERANKR PIWIMGHMVN AIYQIDEFVN LGANSIETDV
SFDKDANPEY TYHGVPCDCG RSCLKWEYFS DFLKGLRKAT TPGDSKYHAK LVLVVFDLKT
GSLYDNQAYD AGKKLAKNLL KHYWNNGNNG GRAYIVLSIP DLNHYKLITG FKETLKSEGH
PELMDKVGHD FSGNDAIGDV GNAYKKAGVT GHVWQSDGIT NCLLRGLSRV KEAVKNRDSS
NGFINKVYYW TVDKRATTRE ALDAGVDGVM TNYPDVITDV LNESAYKAKF RIATYDDNPW
ETFKN
