ID   HOLIN_BPA50             Reviewed;          96 AA.
AC   Q37977;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   23-FEB-2022, entry version 71.
DE   RecName: Full=Antiholin {ECO:0000305};
GN   Name=hol; Synonyms=hol500;
OS   Listeria phage A500 (Bacteriophage A500).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae.
OX   NCBI_TaxID=40522;
OH   NCBI_TaxID=1639; Listeria monocytogenes.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=8577256; DOI=10.1111/j.1365-2958.1995.tb02345.x;
RA   Loessner M.J., Wendlinger G., Scherer S.;
RT   "Heterogeneous endolysins in Listeria monocytogenes bacteriophages: a new
RT   class of enzymes and evidence for conserved holin genes within the
RT   siphoviral lysis cassettes.";
RL   Mol. Microbiol. 16:1231-1241(1995).
CC   -!- FUNCTION: [Isoform Holin]: Accumulates harmlessly in the cytoplasmic
CC       membrane until it reaches a critical concentration that triggers the
CC       formation of micron-scale pores (holes) causing host cell membrane
CC       disruption and endolysin escape into the periplasmic space (By
CC       similarity). Determines the precise timing of host cell lysis (By
CC       similarity). Participates with the endolysin and spanin proteins in the
CC       sequential events which lead to the programmed host cell lysis
CC       releasing the mature viral particles from the host cell (By
CC       similarity). {ECO:0000250|UniProtKB:P03705}.
CC   -!- FUNCTION: Isoform Antiholin: Counteracts the aggregation of the holin
CC       molecules and thus of pore formation. {ECO:0000250|UniProtKB:P03705}.
CC   -!- SUBUNIT: [Isoform Holin]: Homomultimer. Interacts with isoform
CC       Antiholin; this interaction blocks the holin homomultimerization and
CC       delays host cell lysis. {ECO:0000250|UniProtKB:P03705}.
CC   -!- SUBCELLULAR LOCATION: Host cell inner membrane
CC       {ECO:0000250|UniProtKB:P03705}; Multi-pass membrane protein
CC       {ECO:0000250|UniProtKB:P03705}. Note=Classified as a class I holin.
CC       {ECO:0000305}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=Putative antiholin;
CC         IsoId=Q37977-1; Sequence=Displayed;
CC       Name=Holin;
CC         IsoId=Q37977-2; Sequence=VSP_060170;
CC   -!- DOMAIN: Isoform Holin has 3 transmembrane regions whereas isoform
CC       Antiholin lacks the first transmembrane region.
CC       {ECO:0000250|UniProtKB:P03705}.
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DR   EMBL; X85009; CAA59363.1; -; Genomic_DNA.
DR   PIR; S69800; S69800.
DR   RefSeq; YP_001468410.1; NC_009810.1. [Q37977-1]
DR   SMR; Q37977; -.
DR   GeneID; 5601370; -.
DR   KEGG; vg:5601370; -.
DR   GO; GO:0020002; C:host cell plasma membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0019835; P:cytolysis; IEA:UniProtKB-KW.
DR   InterPro; IPR009708; Phage_A118_holin/antiholin.
DR   Pfam; PF06946; Phage_holin_5_1; 1.
PE   3: Inferred from homology;
KW   Alternative initiation; Cytolysis; Host cell inner membrane;
KW   Host cell lysis by virus; Host cell membrane; Host membrane; Membrane;
KW   Transmembrane; Transmembrane helix; Viral release from host cell.
FT   CHAIN           1..96
FT                   /note="Antiholin"
FT                   /id="PRO_0000077799"
FT   TOPO_DOM        1..32
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
FT   TRANSMEM        33..55
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        56..60
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
FT   TRANSMEM        61..81
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        82..96
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
FT   VAR_SEQ         1..3
FT                   /note="Missing (in isoform Holin)"
FT                   /evidence="ECO:0000305"
FT                   /id="VSP_060170"
FT   TOPO_DOM        Q37977-2:1..4
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
FT   TRANSMEM        Q37977-2:5..25
FT                   /note="Helical"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
FT   TOPO_DOM        Q37977-2:26..29
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P03705"
SQ   SEQUENCE   96 AA;  10241 MW;  7849C119648791CE CRC64;
     MMKMEFGKEL LVYMTFLVVV TPVFVQAIKK TELIPSKWLP TVSILVGAIL GALATSLDGS
     GSLATMIWAG ALAGAGGTGL FEQFTNRAKK YGKDDK