ID   GP59_BPT7               Reviewed;          52 AA.
AC   P20406;
DT   01-FEB-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1991, sequence version 1.
DT   04-NOV-2026, entry version 71.
DE   RecName: Full=Probable RecBCD inhibitor gp5.9;
DE   AltName: Full=Gene product 5.9;
DE            Short=Gp5.9;
GN   OrderedLocusNames=5.9;
OS   Escherichia phage T7 (Bacteriophage T7).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Autographivirales; Autotranscriptaviridae; Studiervirinae; Teseptimavirus;
OC   Teseptimavirus T7.
OX   NCBI_TaxID=10760;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RX   PubMed=6864790; DOI=10.1016/s0022-2836(83)80282-4;
RA   Dunn J.J., Studier F.W.;
RT   "Complete nucleotide sequence of bacteriophage T7 DNA and the locations of
RT   T7 genetic elements.";
RL   J. Mol. Biol. 166:477-535(1983).
RN   [2]
RP   SEQUENCE REVISION.
RA   Dunn J.J.;
RL   Submitted (NOV-1993) to the EMBL/GenBank/DDBJ databases.
RN   [3]
RP   FUNCTION.
RX   PubMed=127051; DOI=10.1128/jvi.16.5.1200-1207.1975;
RA   Pacumbaba R., Center M.S.;
RT   "Partial purification and properties of a bacteriophage T7 inhibitor of the
RT   host exonuclease V activity.";
RL   J. Virol. 16:1200-1207(1975).
RN   [4]
RP   FUNCTION, AND MUTAGENESIS OF LEU-23.
RX   PubMed=33157039; DOI=10.1016/j.cell.2020.09.065;
RA   Millman A., Bernheim A., Stokar-Avihail A., Fedorenko T., Voichek M.,
RA   Leavitt A., Oppenheimer-Shaanan Y., Sorek R.;
RT   "Bacterial Retrons Function In Anti-Phage Defense.";
RL   Cell 183:1551-1561(2020).
CC   -!- FUNCTION: Plays a role in the inhibition of the host RecBCD complex
CC       (also called exonuclease V) (Probable). A double mutation in this
CC       protein and the nucleotide kinase gp1.7 protein allows phage to
CC       overcome the retron Ec48 bacteriophage defense system. Overexpression
CC       of the wild-type gp5.9 protein in E.coli with an intact Ec48 retron
CC       leads to a dramatic decrease in cell counts consistent with cell death,
CC       the L23P mutant does not have this effect (PubMed:33157039).
CC       {ECO:0000269|PubMed:33157039, ECO:0000305|PubMed:127051}.
CC   -!- CAUTION: In (PubMed:127051), the authors do not clearly identify gene
CC       5.9 protein but a T7 protein as having this activity. Later
CC       publications assign this activity to gene 5.9 protein.
CC       {ECO:0000305|PubMed:127051}.
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DR   EMBL; V01146; CAA24417.1; -; Genomic_DNA.
DR   PIR; S42315; S42315.
DR   RefSeq; NP_041987.1; NC_001604.1.
DR   PDB; 8B1R; EM; 3.20 A; P/Q=1-52.
DR   PDB; 9GMB; EM; 4.20 A; I/J=1-52.
DR   PDB; 9GMD; EM; 4.00 A; I/J=1-52.
DR   AlphaFoldDB; P20406; -.
DR   EMDB; EMD-15803; -.
DR   EMDB; EMD-51447; -.
DR   EMDB; EMD-51448; -.
DR   SMR; P20406; -.
DR   GeneID; 1261037; -.
DR   KEGG; vg:1261037; -.
DR   OrthoDB; 25722at10239; -.
DR   Proteomes; UP000000840; Segment.
DR   GO; GO:0052170; P:symbiont-mediated suppression of host innate immune response; IEA:UniProtKB-KW.
DR   InterPro; IPR058007; Gp5.9.
DR   Pfam; PF25708; Phage_T7_Gp5_9; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Host-virus interaction;
KW   Inhibition of host innate immune response by virus; Reference proteome;
KW   Viral immunoevasion.
FT   CHAIN           1..52
FT                   /note="Probable RecBCD inhibitor gp5.9"
FT                   /id="PRO_0000106503"
FT   MUTAGEN         23
FT                   /note="L->P: Allows phage to overcome the retron Ec48
FT                   defense system; when associated with 'C-128' in the gp1.7
FT                   protein. Is not toxic when expressed alone in E.coli."
FT                   /evidence="ECO:0000269|PubMed:33157039"
FT   STRAND          5..9
FT                   /evidence="ECO:0007829|PDB:8B1R"
FT   HELIX           10..48
FT                   /evidence="ECO:0007829|PDB:8B1R"
SQ   SEQUENCE   52 AA;  6045 MW;  93A8B8F6173EDB27 CRC64;
     MSRDLVTIPR DVWNDIQGYI DSLERENDSL KNQLMEADEY VAELEEKLNG TS
//