ID   DPO3B_MYCSM             Reviewed;         397 AA.
AC   P52851;
DT   01-OCT-1996, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1996, sequence version 1.
DT   25-MAY-2022, entry version 91.
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   Mycolicibacterium smegmatis (Mycobacterium smegmatis).
OC   Bacteria; Actinobacteria; Corynebacteriales; Mycobacteriaceae;
OC   Mycolicibacterium.
OX   NCBI_TaxID=1772;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 607 / DSM 43465 / JCM 20379 / NBRC 3207 / NRRL B-692;
RX   PubMed=8733228; DOI=10.1111/j.1365-2958.1996.tb02617.x;
RA   Salazar L., Fsihi H., De Rossi E., Riccardi G., Rios C., Cole S.T.,
RA   Takiff H.E.;
RT   "Organization of the origins of replication of the chromosomes of
RT   Mycobacterium smegmatis, Mycobacterium leprae and Mycobacterium
RT   tuberculosis and isolation of a functional origin from M. smegmatis.";
RL   Mol. Microbiol. 20:283-293(1996).
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; X92503; CAA63249.1; -; Genomic_DNA.
DR   PIR; S70987; S70987.
DR   RefSeq; WP_011726602.1; NZ_UGQO01000001.1.
DR   AlphaFoldDB; P52851; -.
DR   SMR; P52851; -.
DR   GeneID; 66738193; -.
DR   OMA; YLIMPVR; -.
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; IPR022637; DNA_polIII_beta_cen.
DR   InterPro; IPR022634; DNA_polIII_beta_N.
DR   PANTHER; PTHR30478; PTHR30478; 1.
DR   Pfam; PF00712; DNA_pol3_beta; 1.
DR   Pfam; PF02767; DNA_pol3_beta_2; 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..397
FT                   /note="Beta sliding clamp"
FT                   /id="PRO_0000105450"
SQ   SEQUENCE   397 AA;  41325 MW;  1D183DE63956CFED CRC64;
     MATTTAGLTD LKFRVVREDF ADAVAWVARS LPTRPTIPVL AGVLLTGTDE GLTISGFDYE
     VSAEVKVSAE IASAGSVLVS GRLLSDITKA LPAKPVEVSV EGTRVSLTCG SARFSLPTLA
     VEDYPALPAL PEETGVIASD LFAEAIGQVA VAAGRDDTLP MLTGIRVEIS GESVVLAATD
     RFRLAVRELT WVTTAGDVEA AVLVPAKTLA EAAKAGTDGN QVHLALGSGA SVGKDGLLGI
     RSEGKRSTTR LLDAEFPKFR QLLPAEHTAV ATIGVAELTE AIKRVALVAD RGAQIRMEFS
     DDTLKLSAGA DDVGRAEEDL PVDFAGEPLT IAFNPTYLTD GLGSLHSERV TFGFTTPSRP
     AVLRPAGEDD GANGGSGPFP AAKTDYVYLL MPVRLPG