ID   HOL26_BPSPP             Reviewed;          82 AA.
AC   O48472;
DT   12-APR-2017, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-1998, sequence version 1.
DT   23-FEB-2022, entry version 63.
DE   RecName: Full=Putative antiholin {ECO:0000250|UniProtKB:P27360};
GN   Name=26;
OS   Bacillus phage SPP1 (Bacteriophage SPP1).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae.
OX   NCBI_TaxID=10724;
OH   NCBI_TaxID=1423; Bacillus subtilis.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=9434185; DOI=10.1016/s0378-1119(97)00547-7;
RA   Alonso J.C., Luder G., Stiege A.C., Chai S., Weise F., Trautner T.A.;
RT   "The complete nucleotide sequence and functional organization of Bacillus
RT   subtilis bacteriophage SPP1.";
RL   Gene 204:201-212(1997).
RN   [2]
RP   FUNCTION.
RX   PubMed=27328857; DOI=10.1111/mmi.13448;
RA   Fernandes S., Sao-Jose C.;
RT   "More than a hole: the holin lethal function may be required to fully
RT   sensitize bacteria to the lytic action of canonical endolysins.";
RL   Mol. Microbiol. 102:92-106(2016).
RN   [3]
RP   SUBCELLULAR LOCATION.
RX   PubMed=27825035; DOI=10.1016/j.virol.2016.10.030;
RA   Fernandes S., Sao-Jose C.;
RT   "Probing the function of the two holin-like proteins of bacteriophage
RT   SPP1.";
RL   Virology 500:184-189(2017).
CC   -!- FUNCTION: [Isoform Holin-like protein 26]: Probably functions as a
CC       holin together with holin-like protein 26. Accumulates harmlessly in
CC       the cytoplasmic membrane until it reaches a critical concentration that
CC       triggers the formation of micron-scale pores (holes) causing host cell
CC       membrane disruption and endolysin escape into the periplasmic space.
CC       Determines the precise timing of host cell lysis.
CC       {ECO:0000305|PubMed:27328857}.
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-like protein 26]: Homomultimer. Interacts with
CC       isoform Antiholin; this interaction blocks the holin
CC       homomultimerization and delays host cell lysis.
CC       {ECO:0000250|UniProtKB:P03705}.
CC   -!- SUBCELLULAR LOCATION: Host cell inner membrane
CC       {ECO:0000269|PubMed:27825035}; Multi-pass membrane protein
CC       {ECO:0000255}. Note=Classified as a class II holin.
CC       {ECO:0000250|UniProtKB:P27360}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=Antiholin {ECO:0000250|UniProtKB:P27360};
CC         IsoId=O48472-1; Sequence=Displayed;
CC       Name=Holin-like protein 26 {ECO:0000250|UniProtKB:P27360};
CC         IsoId=O48472-2; Sequence=VSP_058890;
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DR   EMBL; X97918; CAA66519.1; -; Genomic_DNA.
DR   PIR; T42312; T42312.
DR   RefSeq; NP_690704.1; NC_004166.2. [O48472-1]
DR   SMR; O48472; -.
DR   TCDB; 1.E.31.1.13; the spp1 holin (spp1 holin) family.
DR   GeneID; 955250; -.
DR   KEGG; vg:955250; -.
DR   Proteomes; UP000002559; Genome.
DR   GO; GO:0020002; C:host cell plasma membrane; IDA:CACAO.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0019835; P:cytolysis; IEA:UniProtKB-KW.
DR   InterPro; IPR006479; Holin.
DR   Pfam; PF04688; Holin_SPP1; 1.
DR   TIGRFAMs; TIGR01592; holin_SPP1; 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   Reference proteome; Transmembrane; Transmembrane helix;
KW   Viral release from host cell.
FT   CHAIN           1..82
FT                   /note="Putative antiholin"
FT                   /evidence="ECO:0000250|UniProtKB:P27360"
FT                   /id="PRO_0000439631"
FT   TOPO_DOM        1..8
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000305"
FT   TRANSMEM        9..25
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        26..40
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000305"
FT   TRANSMEM        41..57
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        58..82
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000305"
FT   VAR_SEQ         1..2
FT                   /note="Missing (in isoform Holin-like protein 26)"
FT                   /evidence="ECO:0000250|UniProtKB:P27360"
FT                   /id="VSP_058890"
SQ   SEQUENCE   82 AA;  9391 MW;  558F709AD9E0D3A0 CRC64;
     MKMDTGTKVR TILFLIAWVN QLLSFDNLEP IPVDETTAQQ VYDAVSVLFT IVVTVWTSFK
     NNYLTLKGRK QREALKKNGL TK