ID   E2BA_ECOLX              Reviewed;         263 AA.
AC   P43528;
DT   01-NOV-1995, integrated into UniProtKB/Swiss-Prot.
DT   05-SEP-2012, sequence version 2.
DT   03-AUG-2022, entry version 80.
DE   RecName: Full=Heat-labile enterotoxin IIB, A chain;
DE            Short=LT-IIB;
DE   Flags: Precursor;
OS   Escherichia coli.
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=562;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=Isolate 41;
RX   PubMed=2670900; DOI=10.1128/jb.171.9.4945-4952.1989;
RA   Pickett C.L., Twiddy E.M., Coker C., Holmes R.K.;
RT   "Cloning, nucleotide sequence, and hybridization studies of the type IIb
RT   heat-labile enterotoxin gene of Escherichia coli.";
RL   J. Bacteriol. 171:4945-4952(1989).
RN   [2]
RP   SEQUENCE REVISION TO 89.
RA   Jobling M.G., Holmes R.K.;
RL   Submitted (NOV-2011) to the EMBL/GenBank/DDBJ databases.
RN   [3]
RP   X-RAY CRYSTALLOGRAPHY (2.25 ANGSTROMS).
RX   PubMed=8805549; DOI=10.1016/s0969-2126(96)00073-1;
RA   van den Akker F., Sarfaty S., Twiddy E.M., Connell T.D., Holmes R.K.,
RA   Hol W.G.J.;
RT   "Crystal structure of a new heat-labile enterotoxin, LT-IIb.";
RL   Structure 4:665-678(1996).
CC   -!- FUNCTION: The biological activity of the toxin is produced by the A
CC       chain, which activates intracellular adenyl cyclase.
CC   -!- SUBUNIT: Heterohexamer of one A chain and of five B chains.
CC   -!- SIMILARITY: Belongs to the enterotoxin A family. {ECO:0000305}.
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DR   EMBL; JQ031712; AAA53285.2; -; Genomic_DNA.
DR   PDB; 1TII; X-ray; 2.25 A; A=21-210, C=211-263.
DR   PDBsum; 1TII; -.
DR   AlphaFoldDB; P43528; -.
DR   SMR; P43528; -.
DR   ComplexPortal; CPX-2304; Heat-labile enterotoxin IIB complex.
DR   DIP; DIP-6216N; -.
DR   IntAct; P43528; 1.
DR   PRIDE; P43528; -.
DR   EvolutionaryTrace; P43528; -.
DR   GO; GO:0005615; C:extracellular space; IEA:InterPro.
DR   GO; GO:0044385; C:integral to membrane of host cell; IC:ComplexPortal.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0044501; P:modulation of signal transduction in another organism; IC:ComplexPortal.
DR   DisProt; DP03023; -.
DR   InterPro; IPR001144; Enterotoxin_A.
DR   Pfam; PF01375; Enterotoxin_a; 1.
DR   PRINTS; PR00771; ENTEROTOXINA.
PE   1: Evidence at protein level;
KW   3D-structure; Disulfide bond; Enterotoxin; Signal; Toxin; Virulence.
FT   SIGNAL          1..20
FT   CHAIN           21..263
FT                   /note="Heat-labile enterotoxin IIB, A chain"
FT                   /id="PRO_0000019354"
FT   ACT_SITE        130
FT   BINDING         26..39
FT                   /ligand="NAD(+)"
FT                   /ligand_id="ChEBI:CHEBI:57540"
FT   DISULFID        205..217
FT   STRAND          22..29
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           31..37
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   TURN            49..51
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           59..64
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   STRAND          70..72
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           84..94
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   STRAND          99..107
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   STRAND          112..114
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           115..119
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           120..122
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           126..128
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   STRAND          131..134
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           139..141
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   STRAND          142..149
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           165..168
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           176..180
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           190..193
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           197..199
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           203..205
FT                   /evidence="ECO:0007829|PDB:1TII"
FT   HELIX           217..248
FT                   /evidence="ECO:0007829|PDB:1TII"
SQ   SEQUENCE   263 AA;  29519 MW;  4F648DBDF99CA791 CRC64;
     MAKVISFFIS LFLISFPLYA NDYFRADSRT PDEVRRSGGL IPRGQDEAYE RGTPININLY
     DHARGTATGN TRYNDGYVST TTTLRQAHFL GQNMLGGYNE YYIYVVAAAP NLFDVNGVLG
     RYSPYPSENE YAALGGIPLS QIIGWYRVSF GAIEGGMHRN RDYRRDLFRG LSAAPNEDGY
     RIAGFPDGFP AWEEVPWREF APNSCLPNNK ASSDTTCASL TNKLSQHDLA DFKKYIKRKF
     TLMTLLSINN DGFFSNNGGK DEL