ID   SPAN1_BPP21             Reviewed;         153 AA.
AC   P27358;
DT   01-AUG-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1992, sequence version 1.
DT   07-APR-2021, entry version 71.
DE   RecName: Full=Spanin, inner membrane subunit {ECO:0000255|HAMAP-Rule:MF_04137};
DE            Short=i-spanin {ECO:0000255|HAMAP-Rule:MF_04137};
DE   AltName: Full=Lysis protein Rz {ECO:0000255|HAMAP-Rule:MF_04137};
GN   Name=Rz;
OS   Enterobacteria phage P21 (Bacteriophage 21) (Bacteriophage P21).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae; Lambdavirus.
OX   NCBI_TaxID=10711;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=2019562; DOI=10.1128/jb.173.9.2897-2905.1991;
RA   Bonovich M.T., Young R.;
RT   "Dual start motif in two lambdoid S genes unrelated to lambda S.";
RL   J. Bacteriol. 173:2897-2905(1991).
RN   [2]
RP   FUNCTION.
RX   PubMed=22904283; DOI=10.1128/jb.01245-12;
RA   Berry J., Rajaure M., Pang T., Young R.;
RT   "The spanin complex is essential for lambda lysis.";
RL   J. Bacteriol. 194:5667-5674(2012).
CC   -!- FUNCTION: Component of the spanin complex that disrupts the host outer
CC       membrane and participates in cell lysis during virus exit
CC       (PubMed:22904283). The spanin complex conducts the final step in host
CC       lysis by disrupting the outer membrane after holin and endolysin have
CC       permeabilized the inner membrane and degraded the host peptidoglycans.
CC       Host outer membrane disruption is due to local fusion between the inner
CC       and outer membrane performed by the spanin complex (By similarity).
CC       {ECO:0000255|HAMAP-Rule:MF_04137, ECO:0000305|PubMed:22904283}.
CC   -!- SUBUNIT: Homodimer; disulfide-linked. Interacts (via C-terminus) with
CC       the spanin outer lipoprotein subunit (via C-terminus). Part of the
CC       spanin complex which spans the entire periplasmic space. The spanin
CC       complex is composed of one homodimer of the i-spanin linked by
CC       intermolecular disulfide bonds involving two Cys residues and one
CC       homodimer of the o-spanin covalently linked by an intermolecular
CC       disulfide bond involving one Cys. {ECO:0000255|HAMAP-Rule:MF_04137}.
CC   -!- SUBCELLULAR LOCATION: Host cell inner membrane {ECO:0000255|HAMAP-
CC       Rule:MF_04137}; Single-pass type II membrane protein
CC       {ECO:0000255|HAMAP-Rule:MF_04137}; Periplasmic side {ECO:0000255|HAMAP-
CC       Rule:MF_04137}.
CC   -!- DOMAIN: The coiled coil region is probably involved in host membrane
CC       fusion leading to lysis. {ECO:0000255|HAMAP-Rule:MF_04137}.
CC   -!- SIMILARITY: Belongs to the Lambdavirus i-spanin family.
CC       {ECO:0000255|HAMAP-Rule:MF_04137}.
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DR   EMBL; M65239; AAA32351.1; -; Genomic_DNA.
DR   SMR; P27358; -.
DR   MEROPS; X19.001; -.
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:0019835; P:cytolysis; IEA:UniProtKB-KW.
DR   GO; GO:0090680; P:disruption by virus of host outer membrane; IMP:CACAO.
DR   GO; GO:0044659; P:viral release from host cell by cytolysis; IEA:UniProtKB-UniRule.
DR   HAMAP; MF_04137; I_SPANIN_LAMBDA; 1.
DR   InterPro; IPR004929; I-spanin.
DR   Pfam; PF03245; Phage_lysis; 1.
PE   3: Inferred from homology;
KW   Coiled coil; 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..153
FT                   /note="Spanin, inner membrane subunit"
FT                   /id="PRO_0000077569"
FT   TOPO_DOM        1..3
FT                   /note="Cytoplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P00726"
FT   TRANSMEM        4..24
FT                   /note="Helical; Signal-anchor for type II membrane protein"
FT                   /evidence="ECO:0000255"
FT   TOPO_DOM        25..153
FT                   /note="Periplasmic"
FT                   /evidence="ECO:0000250|UniProtKB:P00726"
FT   COILED          65..92
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04137"
FT   DISULFID        99
FT                   /note="Interchain"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04137"
FT   DISULFID        152
FT                   /note="Interchain"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04137"
SQ   SEQUENCE   153 AA;  17325 MW;  3291A79D77AA1EFD CRC64;
     MNRVTAIISA LVICIIVCLS WAVNHYRDNA ITYKAQRDKN ARELTLANRV ITDIQMRQRD
     VAALDAKYTK ELADAKAEND ALRDDVAAGR RRLHIKAVCQ SVREATTASG VDNAASPRLA
     DTAERDYFTL RERLITMQKQ LEGTQKYINE QCR