ID   STXB_BP788              Reviewed;          89 AA.
AC   Q779K3; Q7B2T7;
DT   04-DEC-2007, integrated into UniProtKB/Swiss-Prot.
DT   05-JUL-2004, sequence version 1.
DT   29-SEP-2021, entry version 57.
DE   RecName: Full=Shiga toxin subunit B;
DE   Flags: Precursor;
GN   Name=stxB;
OS   Shigella phage 7888 (Shigella sonnei bacteriophage 7888).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Podoviridae; Sepvirinae; Traversvirus;
OC   unclassified Traversvirus.
OX   NCBI_TaxID=138946;
OH   NCBI_TaxID=624; Shigella sonnei.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=10232325; DOI=10.1016/s0140-6736(99)00961-7;
RA   Beutin L., Strauch E., Fischer I.;
RT   "Isolation of Shigella sonnei lysogenic for a bacteriophage encoding gene
RT   for production of Shiga toxin.";
RL   Lancet 353:1498-1498(1999).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=11705937; DOI=10.1128/iai.69.12.7588-7595.2001;
RA   Strauch E., Lurz R., Beutin L.;
RT   "Characterization of a Shiga toxin-encoding temperate bacteriophage of
RT   Shigella sonnei.";
RL   Infect. Immun. 69:7588-7595(2001).
CC   -!- FUNCTION: The B subunit is responsible for the binding of the holotoxin
CC       to specific receptors on the target cell surface, such as
CC       globotriaosylceramide (Gb3) in human intestinal microvilli.
CC       {ECO:0000250}.
CC   -!- SUBUNIT: Shiga toxin contains a single subunit A and five copies of
CC       subunit B. {ECO:0000250}.
CC   -!- DOMAIN: There are three Gb3-binding sites in each subunit B monomer,
CC       allowing for a tighter binding to the target cell. Binding sites 1 and
CC       2 have higher binding affinities than site 3 (By similarity).
CC       {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the stxB family. {ECO:0000305}.
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DR   EMBL; AJ132761; CAA10764.1; -; Genomic_DNA.
DR   EMBL; AJ279086; CAC12888.1; -; Genomic_DNA.
DR   SMR; Q779K3; -.
DR   GO; GO:0005576; C:extracellular region; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0019836; P:hemolysis by symbiont of host erythrocytes; IEA:InterPro.
DR   GO; GO:0098676; P:modulation of host virulence by virus; IEA:UniProtKB-KW.
DR   InterPro; IPR008992; Enterotoxin.
DR   InterPro; IPR003189; SLT_beta.
DR   Pfam; PF02258; SLT_beta; 1.
DR   SUPFAM; SSF50203; SSF50203; 1.
PE   3: Inferred from homology;
KW   Disulfide bond; Modulation of host virulence by virus; Signal; Toxin;
KW   Viral exotoxin; Virulence.
FT   SIGNAL          1..20
FT                   /evidence="ECO:0000255"
FT   CHAIN           21..89
FT                   /note="Shiga toxin subunit B"
FT                   /id="PRO_0000312307"
FT   DISULFID        24..77
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   89 AA;  9743 MW;  C78F7795CCD7242E CRC64;
     MKKTLLIAAS LSFFSASALA TPDCVTGKVE YTKYNDDDTF TVKVGDKELF TNRWNLQSLL
     LSAQITGMTV TIKTNACHNG GGFSEVIFR