ID   DPO3B_SPICI             Reviewed;         363 AA.
AC   P34029;
DT   01-FEB-1994, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1994, sequence version 1.
DT   25-MAY-2022, entry version 79.
DE   RecName: Full=Beta sliding clamp;
DE            Short=Beta clamp;
DE            Short=Sliding clamp;
DE   AltName: Full=Beta-clamp processivity factor;
DE   AltName: Full=DNA polymerase III beta sliding clamp subunit;
DE   AltName: Full=DNA polymerase III subunit beta;
GN   Name=dnaN;
OS   Spiroplasma citri.
OC   Bacteria; Tenericutes; Mollicutes; Entomoplasmatales; Spiroplasmataceae;
OC   Spiroplasma.
OX   NCBI_TaxID=2133;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=R8A2HP;
RX   PubMed=7764984; DOI=10.1007/bf01570187;
RA   Ye F., Renaudin J., Bove J.M., Laigret F.;
RT   "Cloning and sequencing of the replication origin (oriC) of the Spiroplasma
RT   citri chromosome and construction of autonomously replicating artificial
RT   plasmids.";
RL   Curr. Microbiol. 29:23-29(1994).
CC   -!- FUNCTION: Confers DNA tethering and processivity to DNA polymerases and
CC       other proteins. Acts as a clamp, forming a ring around DNA (a reaction
CC       catalyzed by the clamp-loading complex) which diffuses in an ATP-
CC       independent manner freely and bidirectionally along dsDNA. Initially
CC       characterized for its ability to contact the catalytic subunit of DNA
CC       polymerase III (Pol III), a complex, multichain enzyme responsible for
CC       most of the replicative synthesis in bacteria; Pol III exhibits 3'-5'
CC       exonuclease proofreading activity. The beta chain is required for
CC       initiation of replication as well as for processivity of DNA
CC       replication. {ECO:0000250|UniProtKB:P0A988}.
CC   -!- SUBUNIT: Forms a ring-shaped head-to-tail homodimer around DNA which
CC       binds and tethers DNA polymerases and other proteins to the DNA. The
CC       DNA replisome complex has a single clamp-loading complex (3 tau and 1
CC       each of delta, delta', psi and chi subunits) which binds 3 Pol III
CC       cores (1 core on the leading strand and 2 on the lagging strand) each
CC       with a beta sliding clamp dimer. Additional proteins in the replisome
CC       are other copies of gamma, psi and chi, Ssb, DNA helicase and RNA
CC       primase. {ECO:0000250|UniProtKB:P0A988}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P0A988}.
CC   -!- SIMILARITY: Belongs to the beta sliding clamp family. {ECO:0000305}.
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DR   EMBL; Z19108; CAA79522.1; -; Genomic_DNA.
DR   PIR; S35733; S35733.
DR   AlphaFoldDB; P34029; -.
DR   SMR; P34029; -.
DR   STRING; 2133.SCITRI_002; -.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0009360; C:DNA polymerase III complex; IEA:InterPro.
DR   GO; GO:0008408; F:3'-5' exonuclease activity; IEA:InterPro.
DR   GO; GO:0003677; F:DNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0003887; F:DNA-directed DNA polymerase activity; IEA:UniProtKB-KW.
DR   GO; GO:0006260; P:DNA replication; IEA:UniProtKB-KW.
DR   CDD; cd00140; beta_clamp; 1.
DR   InterPro; IPR001001; DNA_polIII_beta.
DR   InterPro; IPR022635; DNA_polIII_beta_C.
DR   InterPro; IPR022634; DNA_polIII_beta_N.
DR   PANTHER; PTHR30478; PTHR30478; 1.
DR   Pfam; PF00712; DNA_pol3_beta; 1.
DR   Pfam; PF02768; DNA_pol3_beta_3; 1.
DR   PIRSF; PIRSF000804; DNA_pol_III_b; 1.
DR   SMART; SM00480; POL3Bc; 1.
DR   TIGRFAMs; TIGR00663; dnan; 1.
PE   3: Inferred from homology;
KW   Cytoplasm; DNA replication; DNA-binding; DNA-directed DNA polymerase;
KW   Nucleotidyltransferase; Transferase.
FT   CHAIN           1..363
FT                   /note="Beta sliding clamp"
FT                   /id="PRO_0000105461"
SQ   SEQUENCE   363 AA;  41329 MW;  C969A39BEFEF26D6 CRC64;
     MIVNIKRDKI LDELLKVSRI ISQKTLIPSL LGILIEVKKD KITFTTSDGD TSIKSEIMGN
     DLNITRIGSV LIKNKFIVEV IRKIEDEFIT LEVVEGNLIK IKANNFDSVL NTLNSADYPH
     LSFETEGKEI IFTSTVLKEI ISQTSFAIGE KEKRIVFNGL NIKTDQNNKE LIITATDSFR
     LSCKKIDYSN NYNFDVIIPG KFINEIGRLI SENDQVSELL LIIINCKQKI IEGKYPDTSK
     VIRTSFNTSL TINNRAIIKI IERRSVLSNE TMTTIVTLKI KEQKVLVTSF TQEIGNTEEE
     IRDFKVEGTD QIIAFNSKYI LDALKAFKTK EITIKMIDER KPLIITANDD QTLQQLVLPI
     RSY