ID   TERS_BPG20              Reviewed;         171 AA.
AC   A0A1L4BKP6;
DT   08-MAY-2019, integrated into UniProtKB/Swiss-Prot.
DT   15-MAR-2017, sequence version 1.
DT   03-AUG-2022, entry version 22.
DE   RecName: Full=Terminase, small subunit {ECO:0000303|PubMed:23908032};
DE   AltName: Full=DNA-packaging protein gp79 {ECO:0000305};
DE   AltName: Full=Gene product 79 {ECO:0000305};
DE            Short=gp79 {ECO:0000305};
GN   ORFNames=G20c_79 {ECO:0000312|EMBL:API81887.1};
OS   Thermus phage G20c (Thermus thermophilus phage G20c).
OC   Viruses; Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes;
OC   Caudovirales; Siphoviridae; Oshimavirus; unclassified Oshimavirus.
OX   NCBI_TaxID=1406341;
OH   NCBI_TaxID=274; Thermus thermophilus.
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA], AND X-RAY CRYSTALLOGRAPHY
RP   (2.30 ANGSTROMS) OF 1-138.
RX   PubMed=28100693; DOI=10.1093/nar/gkw1354;
RA   Xu R.G., Jenkins H.T., Chechik M., Blagova E.V., Lopatina A., Klimuk E.,
RA   Minakhin L., Severinov K., Greive S.J., Antson A.A.;
RT   "Viral genome packaging terminase cleaves DNA using the canonical RuvC-like
RT   two-metal catalysis mechanism.";
RL   Nucleic Acids Res. 45:3580-3590(2017).
RN   [2]
RP   X-RAY CRYSTALLOGRAPHY (2.80 ANGSTROMS), AND SUBUNIT.
RX   PubMed=23908032; DOI=10.1107/s1744309113017016;
RA   Loredo-Varela J., Chechik M., Levdikov V.M., Abd-El-Aziz A., Minakhin L.,
RA   Severinov K., Smits C., Antson A.A.;
RT   "The putative small terminase from the thermophilic dsDNA bacteriophage
RT   G20C is a nine-subunit oligomer.";
RL   Acta Crystallogr. F 69:876-879(2013).
CC   -!- FUNCTION: The terminase small subunit binds to the packaging initiation
CC       site and regulates the ATPase activity of the terminase large subunit
CC       (By similarity). The terminase lies at a unique vertex of the procapsid
CC       and is composed of two subunits, a small terminase subunit involved in
CC       viral DNA recognition (packaging sequence), and a large terminase
CC       subunit (By similarity). Both terminase subunits heterooligomerize and
CC       are docked on the portal protein to form the packaging machine (By
CC       similarity). {ECO:0000250|UniProtKB:P04893}.
CC   -!- SUBUNIT: Homononamer; forms a ring-like structure through which genomic
CC       DNA is translocated into the capsid (PubMed:23908032). Heterodimer with
CC       the terminase large subunit; the active complex is probably
CC       heterooligomeric (By similarity). {ECO:0000250|UniProtKB:P04893,
CC       ECO:0000269|PubMed:23908032}.
CC   -!- SIMILARITY: Belongs to the P23virus small terminase family.
CC       {ECO:0000305}.
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DR   EMBL; KX987127; API81887.1; -; Genomic_DNA.
DR   PDB; 4XVN; X-ray; 2.60 A; A/B/C/D/E/F=1-171.
DR   PDB; 6EJQ; X-ray; 2.30 A; A/B/C/D/E/F/G/H/I=1-138.
DR   PDBsum; 4XVN; -.
DR   PDBsum; 6EJQ; -.
DR   SMR; A0A1L4BKP6; -.
DR   Proteomes; UP000223104; Genome.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   3D-structure; DNA-binding; Reference proteome; Viral genome packaging;
KW   Viral release from host cell.
FT   CHAIN           1..171
FT                   /note="Terminase, small subunit"
FT                   /id="PRO_0000447197"
FT   HELIX           3..14
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   HELIX           19..27
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   STRAND          30..32
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   HELIX           36..50
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   HELIX           56..92
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   STRAND          99..101
FT                   /evidence="ECO:0007829|PDB:4XVN"
FT   HELIX           109..135
FT                   /evidence="ECO:0007829|PDB:6EJQ"
FT   STRAND          137..139
FT                   /evidence="ECO:0007829|PDB:4XVN"
SQ   SEQUENCE   171 AA;  18794 MW;  75A61E19099223D9 CRC64;
     MSVSFRDRVL KLYLLGFDPS EIAQTLSLDV KRKVTEEEVL HVLAEARELL SALPSLEDIR
     AEVGQALERA RIFQKDLLAI YQNMLRNYNA MMEGLTEHPD GTPVIGVRPA DIAAMADRIM
     KIDQERITAL LNSLKVLGHV GSTTAGALPS ATELVSVEEL VAEVVDEAPK T