ID   VGA_BPG4                Reviewed;         554 AA.
AC   P03632; Q38365;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   23-FEB-2022, entry version 89.
DE   RecName: Full=A protein;
DE   AltName: Full=GPA;
GN   Name=A;
OS   Escherichia phage G4 (Bacteriophage G4).
OC   Viruses; Monodnaviria; Sangervirae; Phixviricota; Malgrandaviricetes;
OC   Petitvirales; Microviridae; Bullavirinae; Gequatrovirus.
OX   NCBI_TaxID=10843;
OH   NCBI_TaxID=562; Escherichia coli.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=714153; DOI=10.1038/276236a0;
RA   Godson G.N., Barrell B.G., Staden R., Fiddes J.C.;
RT   "Nucleotide sequence of bacteriophage G4 DNA.";
RL   Nature 276:236-247(1978).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 402-526.
RX   PubMed=160951; DOI=10.1016/0022-2836(79)90249-3;
RA   Fiddes J.C., Godson G.N.;
RT   "Evolution of the three overlapping gene systems in G4 and phi X174.";
RL   J. Mol. Biol. 133:19-43(1979).
CC   -!- FUNCTION: The A protein is a specific endonuclease that cleaves the
CC       viral strand of supertwisted, closed circular DNA at a unique site in
CC       the A gene. The A protein also causes relaxation of supertwisted DNA
CC       and forms a complex with viral DNA that has a discontinuity in gene A
CC       of the viral strand.
CC   -!- FUNCTION: The A* protein binds to double-stranded DNA and prevents
CC       their hydrolysis by nucleases.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative initiation; Named isoforms=2;
CC       Name=A;
CC         IsoId=P03632-1; Sequence=Displayed;
CC       Name=A*;
CC         IsoId=P03632-2; Sequence=VSP_018963;
CC   -!- SEQUENCE CAUTION:
CC       Sequence=CAA24012.1; Type=Erroneous initiation; Evidence={ECO:0000305};
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DR   EMBL; V00657; CAA24011.1; -; Genomic_DNA.
DR   EMBL; V00657; CAA24012.1; ALT_INIT; Genomic_DNA.
DR   EMBL; M10636; AAA32313.1; -; Genomic_DNA.
DR   PIR; A04240; ZABPG4.
DR   SMR; P03632; -.
DR   Proteomes; UP000002140; Genome.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0004519; F:endonuclease activity; IEA:UniProtKB-KW.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0006260; P:DNA replication; IEA:UniProtKB-KW.
DR   GO; GO:0039693; P:viral DNA genome replication; IEA:UniProtKB-KW.
DR   InterPro; IPR008766; Replication_gene_A.
DR   Pfam; PF05840; Phage_GPA; 1.
PE   4: Predicted;
KW   Alternative initiation; DNA replication; DNA-binding; Endonuclease;
KW   Hydrolase; Metal-binding; Nuclease; Reference proteome;
KW   Viral DNA replication; Zinc; Zinc-finger.
FT   CHAIN           1..554
FT                   /note="A protein"
FT                   /id="PRO_0000003315"
FT   ZN_FING         287..309
FT                   /evidence="ECO:0000255"
FT   ACT_SITE        384
FT                   /note="O-(5'-phospho-DNA)-tyrosine intermediate"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        388
FT                   /note="O-(5'-phospho-DNA)-tyrosine intermediate"
FT                   /evidence="ECO:0000250"
FT   VAR_SEQ         1..213
FT                   /note="Missing (in isoform A*)"
FT                   /evidence="ECO:0000305"
FT                   /id="VSP_018963"
FT   CONFLICT        320
FT                   /note="D -> H (in Ref. 1; CAA24011/CAA24012)"
FT                   /evidence="ECO:0000305"
SQ   SEQUENCE   554 AA;  63382 MW;  00C8E6BC14AA1D96 CRC64;
     MFKVHSDYFS KPNIDAIKPL VETAGMSVLT QSPNLRIWKQ CNTRIKLLEE ILAHYTNGIR
     RDDNGDFWMN PNSQLATTIA YRAHHKGHNP KFKQYPETFT LDDIITGKPI PQTAPDELQL
     SDEIVEDYRL TVLSIIEELQ ECYDVLGQLD INNTIDHKPL GNDHWNLLYE KPVYKHWYQL
     VSNRPLKDIR ADYNYAKAKG VKDECSKILE ESTMKSRRGF TVQRLMNAMR TAHSKGWYVV
     FDTLTLADDR LKDFYDNPNA LRDYFRDIGR MVLTAEGRSV HDSSSDCYQY FCVPEYGTQH
     GRLHFHAVHL MRTLPLGSLD PNFGKLVRIN RQINSLQNTW PYGYSMPIAV RYSQDAFSRA
     GWLWPVDSKG EPLKATSYMA VGFYVAKYVN KKSDIDMAVK GLGNKEWNNS LKTKINLIPK
     KVFRIRMSRN FGMKLLSMAH LSAETLMELT QVGYDVTPFN NILKQNAKKE LKSRLAKKSV
     ADVLEAQPVT TNLLKFMRNL TRTIGASNLQ SFIASMTTKL TSTDISDETK NYVASAGIAV
     ANLRIKSKWT AGGK