ID   HOLIN_BPK3              Reviewed;         218 AA.
AC   P10393;
DT   01-JUL-1989, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-1989, sequence version 1.
DT   02-DEC-2020, entry version 47.
DE   RecName: Full=Holin {ECO:0000255|HAMAP-Rule:MF_04104};
DE   AltName: Full=Lysis protein;
GN   Name=T;
OS   Enterobacteria phage K3 (Bacteriophage K3).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Myoviridae; Tevenvirinae; Tequatrovirus;
OC   unclassified Tequatrovirus.
OX   NCBI_TaxID=10674;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=3597316; DOI=10.1128/jb.169.7.2956-2961.1987;
RA   Riede I.;
RT   "Lysis gene t of T-even bacteriophages: evidence that colicins and
RT   bacteriophage genes have common ancestors.";
RL   J. Bacteriol. 169:2956-2961(1987).
CC   -!- FUNCTION: Accumulates harmlessly in the cytoplasmic membrane until it
CC       reaches a critical concentration that triggers the formation of micron-
CC       scale pores (holes) causing host cell membrane disruption and endolysin
CC       escape into the periplasmic space. Determines the precise timing of
CC       host cell lysis. Participates with the endolysin and spanin proteins in
CC       the sequential events which lead to the programmed host cell lysis
CC       releasing the mature viral particles from the host cell.
CC       {ECO:0000255|HAMAP-Rule:MF_04104}.
CC   -!- SUBUNIT: Homomultimer. Interacts (via C-terminus) with antiholin (via
CC       C-terminus); this interaction blocks the holin homomultimerization and
CC       delays host cell lysis. Interacts (via N-terminus) with the lysis
CC       inhibition accessory protein rIII; this interaction stabilizes the
CC       holin-antiholin complex thereby resulting in a robust block of the hole
CC       formation. {ECO:0000255|HAMAP-Rule:MF_04104}.
CC   -!- SUBCELLULAR LOCATION: Host cell inner membrane {ECO:0000255|HAMAP-
CC       Rule:MF_04104}; Single-pass type II membrane protein
CC       {ECO:0000255|HAMAP-Rule:MF_04104}; Periplasmic side {ECO:0000255|HAMAP-
CC       Rule:MF_04104}. Note=Classified as a class III holin.
CC       {ECO:0000255|HAMAP-Rule:MF_04104}.
CC   -!- PTM: Disulfide bond is required for functionality. {ECO:0000255|HAMAP-
CC       Rule:MF_04104}.
CC   -!- SIMILARITY: Belongs to the T4likevirus holin family.
CC       {ECO:0000255|HAMAP-Rule:MF_04104}.
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DR   EMBL; M16812; AAA88415.1; -; Genomic_DNA.
DR   PIR; A27083; YVBPK3.
DR   SMR; P10393; -.
DR   GO; GO:0020002; C:host cell plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-UniRule.
DR   GO; GO:0034291; F:canonical holin activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0019835; P:cytolysis; IEA:UniProtKB-KW.
DR   HAMAP; MF_04104; HOLIN_T4; 1.
DR   InterPro; IPR020982; Phage_T4_GpT_holin.
DR   Pfam; PF11031; Phage_holin_T; 1.
PE   3: Inferred from homology;
KW   Cytolysis; Disulfide bond; Host cell inner membrane;
KW   Host cell lysis by virus; Host cell membrane; Host membrane; Membrane;
KW   Signal-anchor; Transmembrane; Transmembrane helix;
KW   Viral release from host cell.
FT   CHAIN           1..218
FT                   /note="Holin"
FT                   /id="PRO_0000165067"
FT   TOPO_DOM        1..34
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04104"
FT   TRANSMEM        35..49
FT                   /note="Helical; Signal-anchor for type II membrane protein"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04104"
FT   TOPO_DOM        50..218
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04104"
FT   DISULFID        175..207
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04104"
SQ   SEQUENCE   218 AA;  25223 MW;  21B4DC02ACA0ECF6 CRC64;
     MAAPRISFSP SDILFGVLDR LFKDNATGKV LASRVAVVIL LFMMAIVWYR GDSFFEYYKQ
     SKYETYSEII EKERNARFES VALEQLQIVH ISSEADFSAV YSFRPKNLNY FVDIIAYEGK
     LPSTISEKSL GGYPVDKTMD EYTVHLNGRH YYSNSKFAFL PTKKPTPEIN YMYSCPYFNL
     DNIYAGTITM YWYRNDHISN DRLESICSQA ARILGRAK