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HAMAP rule MF_04104

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General rule information [?]

Accession MF_04104
Dates 18-OCT-2016 (Created)
1-DEC-2022 (Last updated, Version 9)
Viruses; Caudoviricetes
Template P06808 (HOLIN_BPT4)

Propagated annotation [?]

Identifier, protein and gene names [?]

Protein name
RecName: Full=Holin;

Comments [?]

Function Accumulates harmlessly in the cytoplasmic membrane until it reaches a critical concentration that triggers the formation of micron-scale pores (holes) causing host cell membrane disruption and endolysin escape into the periplasmic space. Determines the precise timing of host cell lysis. Regulated by specific antiholins that somehow sense superinfections and then delay lysis. Participates with the endolysin and spanin proteins in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles from the host cell.
Subunit Homomultimer. Heterotetramer composed of 2 holin and 2 antiholin. The holin-antiholin complex binds dsDNA. Interacts (via C-terminus) with antiholin (via C-terminus); this interaction blocks the holin homomultimerization and delays host cell lysis. Interacts (via N-terminus) with the lysis inhibition accessory protein rIII; this interaction stabilizes the holin-antiholin complex thereby resulting in a robust block of the hole formation.
Subcellular location Host cell inner membrane; Single-pass type II membrane protein; Periplasmic side. Note=Classified as a class III holin.
Domain The C-terminus serves, in association with the antiholin, as a DNA sensor for lysis inhibition under superinfection conditions.
case <FTTag:disulf>
Ptm Disulfide bond is required for functionality.
end case
Similarity Belongs to the T4likevirus holin family.

Keywords [?]

case <FTTag:disulf>
end case

Gene Ontology [?]

GO:0140911; Molecular function: pore-forming activity.
GO:0016020; Cellular component: membrane.
GO:0020002; Cellular component: host cell plasma membrane.

Cross-references [?]

Pfam PF11031; Phage_holin_T; 1;

Features [?]

From: HOLIN_BPT4 (P06808)
Key     From     To       Description   Tag   Condition   FTGroup
TOPO_DOM     Nter     34       Cytoplasmic        
TRANSMEM     35     49       Helical; Signal-anchor for type II membrane protein        
TOPO_DOM     50     Cter       Periplasmic        
DISULFID     175     207           disulf   C-x*-C  

Additional information [?]

Size range 188-243 amino acids
Related rules None
Fusion None