ID   HOLD_ECOLI              Reviewed;         137 AA.
AC   P28632; Q2M5U6;
DT   01-DEC-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-DEC-1992, sequence version 1.
DT   04-NOV-2026, entry version 182.
DE   RecName: Full=DNA polymerase III subunit psi {ECO:0000303|PubMed:8389364};
DE            EC=2.7.7.7;
DE   AltName: Full=Accessory clamp loader complex subunit psi {ECO:0000305};
DE   AltName: Full=Replication clamp loader subunit HolD {ECO:0000305};
GN   Name=holD {ECO:0000303|PubMed:8389364};
GN   OrderedLocusNames=b4372, JW4334;
OS   Escherichia coli (strain K12).
OC   Bacteria; Pseudomonadati; Pseudomonadota; Gammaproteobacteria;
OC   Enterobacterales; Enterobacteriaceae; Escherichia.
OX   NCBI_TaxID=83333;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=K12;
RX   PubMed=8389364; DOI=10.1016/s0021-9258(19)50266-6;
RA   Xiao H., Crombie R., Dong Z., Onrust R., O'Donnell M.;
RT   "DNA polymerase III accessory proteins. III. holC and holD encoding chi and
RT   psi.";
RL   J. Biol. Chem. 268:11773-11778(1993).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=K12 / MG1655 / ATCC 47076;
RX   PubMed=8366044; DOI=10.1128/jb.175.17.5604-5610.1993;
RA   Carter J.R., Franden M.A., Aebersold R.H., McHenry C.S.;
RT   "Identification, isolation, and overexpression of the gene encoding the psi
RT   subunit of DNA polymerase III holoenzyme.";
RL   J. Bacteriol. 175:5604-5610(1993).
RN   [3]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=K12;
RX   PubMed=2828880; DOI=10.1007/bf00331153;
RA   Yoshikawa A., Isono S., Sheback A., Isono K.;
RT   "Cloning and nucleotide sequencing of the genes rimI and rimJ which encode
RT   enzymes acetylating ribosomal proteins S18 and S5 of Escherichia coli
RT   K12.";
RL   Mol. Gen. Genet. 209:481-488(1987).
RN   [4]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=K12 / MG1655 / ATCC 47076;
RX   PubMed=7610040; DOI=10.1093/nar/23.12.2105;
RA   Burland V.D., Plunkett G. III, Sofia H.J., Daniels D.L., Blattner F.R.;
RT   "Analysis of the Escherichia coli genome VI: DNA sequence of the region
RT   from 92.8 through 100 minutes.";
RL   Nucleic Acids Res. 23:2105-2119(1995).
RN   [5]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=K12 / MG1655 / ATCC 47076;
RX   PubMed=9278503; DOI=10.1126/science.277.5331.1453;
RA   Blattner F.R., Plunkett G. III, Bloch C.A., Perna N.T., Burland V.,
RA   Riley M., Collado-Vides J., Glasner J.D., Rode C.K., Mayhew G.F.,
RA   Gregor J., Davis N.W., Kirkpatrick H.A., Goeden M.A., Rose D.J., Mau B.,
RA   Shao Y.;
RT   "The complete genome sequence of Escherichia coli K-12.";
RL   Science 277:1453-1462(1997).
RN   [6]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=K12 / W3110 / ATCC 27325 / DSM 5911;
RX   PubMed=16738553; DOI=10.1038/msb4100049;
RA   Hayashi K., Morooka N., Yamamoto Y., Fujita K., Isono K., Choi S.,
RA   Ohtsubo E., Baba T., Wanner B.L., Mori H., Horiuchi T.;
RT   "Highly accurate genome sequences of Escherichia coli K-12 strains MG1655
RT   and W3110.";
RL   Mol. Syst. Biol. 2:E1-E5(2006).
RN   [7]
RP   CHARACTERIZATION.
RX   PubMed=8505305; DOI=10.1016/s0021-9258(19)50267-8;
RA   Xiao H., Dong Z., O'Donnell M.;
RT   "DNA polymerase III accessory proteins. IV. Characterization of chi and
RT   psi.";
RL   J. Biol. Chem. 268:11779-11784(1993).
RN   [8]
RP   FUNCTION, AND SUBUNIT.
RX   PubMed=2040637; DOI=10.1016/s0021-9258(18)99166-0;
RA   Stukenberg P.T., Studwell-Vaughan P.S., O'Donnell M.;
RT   "Mechanism of the sliding beta-clamp of DNA polymerase III holoenzyme.";
RL   J. Biol. Chem. 266:11328-11334(1991).
RN   [9]
RP   REPLISOME COMPLEX, AND SUBUNIT.
RX   PubMed=20413500; DOI=10.1126/science.1185757;
RA   Reyes-Lamothe R., Sherratt D.J., Leake M.C.;
RT   "Stoichiometry and architecture of active DNA replication machinery in
RT   Escherichia coli.";
RL   Science 328:498-501(2010).
RN   [10]
RP   REPLISOME COMPLEX, AND SUBUNIT.
RX   PubMed=22157955; DOI=10.1038/nsmb.2179;
RA   Georgescu R.E., Kurth I., O'Donnell M.E.;
RT   "Single-molecule studies reveal the function of a third polymerase in the
RT   replisome.";
RL   Nat. Struct. Mol. Biol. 19:113-116(2011).
RN   [11]
RP   INTERACTION WITH HOLC (CHI).
RC   STRAIN=K12 / MG1655 / ATCC 47076;
RX   PubMed=26544712; DOI=10.1371/journal.pgen.1005651;
RA   Brown L.T., Sutera V.A. Jr., Zhou S., Weitzel C.S., Cheng Y., Lovett S.T.;
RT   "Connecting replication and repair: YoaA, a helicase-related protein,
RT   promotes azidothymidine tolerance through association with Chi, an
RT   accessory clamp loader protein.";
RL   PLoS Genet. 11:E1005651-E1005651(2015).
RN   [12]
RP   INTERACTION WITH HOLC (CHI).
RX   PubMed=33582602; DOI=10.1016/j.dnarep.2020.103006;
RA   Sutera V.A., Weeks S.J., Dudenhausen E.E., Baggett H.B.R., Shaw M.C.,
RA   Brand K.A., Glass D.J., Bloom L.B., Lovett S.T.;
RT   "Alternative complexes formed by the Escherichia coli clamp loader
RT   accessory protein HolC (x) with replication protein HolD (psi) and repair
RT   protein YoaA.";
RL   DNA Repair 100:103006-103006(2021).
RN   [13]
RP   REVIEW.
RX   PubMed=1575709; DOI=10.1002/bies.950140206;
RA   O'Donnell M.;
RT   "Accessory protein function in the DNA polymerase III holoenzyme from E.
RT   coli.";
RL   Bioessays 14:105-111(1992).
RN   [14]
RP   X-RAY CRYSTALLOGRAPHY IN COMPLEX WITH HOLC (CHI).
RX   PubMed=14717711; DOI=10.1046/j.1432-1033.2003.03944.x;
RA   Gulbis J.M., Kazmirski S.L., Finkelstein J., Kelman Z., O'Donnell M.,
RA   Kuriyan J.;
RT   "Crystal structure of the chi:psi sub-assembly of the Escherichia coli DNA
RT   polymerase clamp-loader complex.";
RL   Eur. J. Biochem. 271:439-449(2004).
CC   -!- FUNCTION: Part of the beta sliding clamp loading complex, which
CC       hydrolyzes ATP to load the beta clamp onto primed DNA to form the DNA
CC       replication pre-initiation complex (PubMed:2040637). DNA polymerase III
CC       is a complex, multichain enzyme responsible for most of the replicative
CC       synthesis in bacteria. This DNA polymerase also exhibits 3' to 5'
CC       exonuclease activity. {ECO:0000269|PubMed:2040637}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=DNA(n) + a 2'-deoxyribonucleoside 5'-triphosphate = DNA(n+1) +
CC         diphosphate; Xref=Rhea:RHEA:22508, Rhea:RHEA-COMP:17339, Rhea:RHEA-
CC         COMP:17340, ChEBI:CHEBI:33019, ChEBI:CHEBI:61560, ChEBI:CHEBI:173112;
CC         EC=2.7.7.7;
CC   -!- SUBUNIT: The DNA polymerase III holoenzyme complex contains at least 10
CC       different subunits organized into 3 functionally essential
CC       subassemblies: the Pol III core, the beta sliding clamp processivity
CC       factor and the clamp-loading complex. The Pol III core (subunits alpha,
CC       epsilon and theta) contains the polymerase and the 3'-5' exonuclease
CC       proofreading activities (PubMed:2040637). The polymerase is tethered to
CC       the template via the dimeric beta sliding clamp processivity factor.
CC       The clamp-loading complex (also called gamma complex) assembles the
CC       beta sliding clamp onto the primed template and plays a central role in
CC       the organization and communication at the replication fork. The clamp-
CC       loading complex contains delta, delta', psi and chi, and 3 copies of
CC       either or both of two different DnaX proteins, gamma and tau. The DNA
CC       replisome complex has a single clamp loader (3 tau and 1 each of delta,
CC       delta', psi and chi subunits) which binds 3 Pol III cores (1 core on
CC       the leading strand and 2 on the lagging strand) each with a beta
CC       sliding clamp dimer. Additional proteins in the replisome are other
CC       copies of gamma, psi (this protein) and chi (holC), SSB, DNA helicase
CC       and RNA primase (PubMed:20413500, PubMed:22157955). The clamp loader
CC       hydrolyzes ATP to assemble the beta processivity factor onto the primed
CC       template (PubMed:2040637) and plays a central role in the organization
CC       and communication at the replication fork. Interacts directly with the
CC       chi subunit (holC) (PubMed:14717711, PubMed:26544712, PubMed:33582602).
CC       {ECO:0000269|PubMed:2040637, ECO:0000269|PubMed:20413500,
CC       ECO:0000269|PubMed:22157955, ECO:0000269|PubMed:26544712,
CC       ECO:0000269|PubMed:33582602}.
CC   -!- INTERACTION:
CC       P28632; P06710: dnaX; NbExp=26; IntAct=EBI-549176, EBI-549140;
CC       P28632; P06710-2: dnaX; NbExp=2; IntAct=EBI-549176, EBI-2604194;
CC       P28632; P28905: holC; NbExp=25; IntAct=EBI-549176, EBI-549169;
CC       P28632; P14294: topB; NbExp=3; IntAct=EBI-549176, EBI-552080;
CC       P28632; P76092: ynbC; NbExp=3; IntAct=EBI-549176, EBI-544837;
CC   -!- SIMILARITY: Belongs to the DNA polymerase III psi/HolD chain family.
CC       {ECO:0000305}.
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DR   EMBL; L04575; AAA24435.1; -; Genomic_DNA.
DR   EMBL; L05387; AAA03076.1; -; Unassigned_DNA.
DR   EMBL; X06117; -; NOT_ANNOTATED_CDS; Genomic_DNA.
DR   EMBL; U14003; AAA97268.1; -; Genomic_DNA.
DR   EMBL; U00096; AAC77325.1; -; Genomic_DNA.
DR   EMBL; AP009048; BAE78360.1; -; Genomic_DNA.
DR   PIR; A48647; A48647.
DR   RefSeq; NP_418789.1; NC_000913.3.
DR   RefSeq; WP_000204012.1; NZ_CP009789.1.
DR   PDB; 1EM8; X-ray; 2.10 A; B/D=26-137.
DR   PDB; 3GLI; X-ray; 3.50 A; O/P=2-28.
DR   PDB; 3SXU; X-ray; 1.85 A; B=2-137.
DR   PDB; 8GIY; EM; 3.70 A; F=1-137.
DR   PDB; 8GIZ; EM; 2.70 A; F=1-137.
DR   PDB; 8GJ0; EM; 2.90 A; F=1-137.
DR   PDB; 8GJ1; EM; 3.00 A; F=1-137.
DR   PDB; 8GJ2; EM; 2.60 A; F=1-137.
DR   PDB; 8GJ3; EM; 2.80 A; F=1-137.
DR   PDB; 9OYB; EM; 3.14 A; J=1-137.
DR   PDB; 9OYC; EM; 2.71 A; J=1-137.
DR   PDB; 9OYD; EM; 2.73 A; J=1-137.
DR   PDB; 9OYE; EM; 2.72 A; J=1-137.
DR   PDB; 9OYF; EM; 3.12 A; J=1-137.
DR   PDB; 9OYG; EM; 2.95 A; J=3-32.
DR   PDB; 9OYH; EM; 2.54 A; J=1-137.
DR   PDB; 9OYI; EM; 2.54 A; J=1-137.
DR   PDB; 9OYJ; EM; 2.53 A; J=1-137.
DR   PDB; 9OYK; EM; 2.60 A; J=1-137.
DR   PDB; 9OYL; EM; 2.88 A; J=3-32.
DR   PDB; 9OYM; EM; 2.60 A; J=1-137.
DR   PDB; 9OYN; EM; 2.70 A; J=1-137.
DR   AlphaFoldDB; P28632; -.
DR   EMDB; EMD-40079; -.
DR   EMDB; EMD-40080; -.
DR   EMDB; EMD-40081; -.
DR   EMDB; EMD-40082; -.
DR   EMDB; EMD-40083; -.
DR   EMDB; EMD-40084; -.
DR   EMDB; EMD-71013; -.
DR   EMDB; EMD-71014; -.
DR   EMDB; EMD-71015; -.
DR   EMDB; EMD-71016; -.
DR   EMDB; EMD-71017; -.
DR   EMDB; EMD-71018; -.
DR   EMDB; EMD-71021; -.
DR   EMDB; EMD-71022; -.
DR   EMDB; EMD-71023; -.
DR   EMDB; EMD-71024; -.
DR   EMDB; EMD-71025; -.
DR   EMDB; EMD-71026; -.
DR   EMDB; EMD-71027; -.
DR   MDposit; P28632; -.
DR   MDRepo; P28632; -.
DR   SMR; P28632; -.
DR   BioGRID; 4262785; 120.
DR   BioGRID; 853167; 4.
DR   ComplexPortal; CPX-1926; DNA polymerase III clamp loader complex.
DR   DIP; DIP-9934N; -.
DR   FunCoup; P28632; 151.
DR   IntAct; P28632; 23.
DR   STRING; 511145.b4372; -.
DR   jPOST; P28632; -.
DR   PaxDb; 511145-b4372; -.
DR   EnsemblBacteria; AAC77325; AAC77325; b4372.
DR   GeneID; 948890; -.
DR   KEGG; ecj:JW4334; -.
DR   KEGG; eco:b4372; -.
DR   KEGG; ecoc:C3026_23620; -.
DR   PATRIC; fig|1411691.4.peg.2316; -.
DR   EchoBASE; EB1386; -.
DR   eggNOG; COG3050; Bacteria.
DR   HOGENOM; CLU_132082_0_0_6; -.
DR   InParanoid; P28632; -.
DR   OMA; AESHCNF; -.
DR   OrthoDB; 5682636at2; -.
DR   PhylomeDB; P28632; -.
DR   BioCyc; EcoCyc:EG11414-MONOMER; -.
DR   BioCyc; MetaCyc:EG11414-MONOMER; -.
DR   BRENDA; 3.6.4.B8; 2026.
DR   EvolutionaryTrace; P28632; -.
DR   PRO; PR:P28632; -.
DR   Proteomes; UP000000625; Chromosome.
DR   GO; GO:0009360; C:DNA polymerase III complex; NAS:ComplexPortal.
DR   GO; GO:0043846; C:DNA polymerase III, clamp loader complex; IPI:ComplexPortal.
DR   GO; GO:0030894; C:replisome; NAS:ComplexPortal.
DR   GO; GO:0008408; F:3'-5' exonuclease activity; IEA:InterPro.
DR   GO; GO:0003887; F:DNA-directed DNA polymerase activity; IDA:EcoCyc.
DR   GO; GO:0006260; P:DNA replication; NAS:ComplexPortal.
DR   GO; GO:0006261; P:DNA-templated DNA replication; NAS:ComplexPortal.
DR   GO; GO:0009314; P:response to radiation; IMP:EcoCyc.
DR   Gene3D; 3.40.50.10220; DNA polymerase III, psi subunit; 1.
DR   InterPro; IPR004615; DNA_pol_III_psi.
DR   InterPro; IPR036654; DNA_pol_III_psi_sf.
DR   InterPro; IPR018382; DNA_pol_III_psi_subgr.
DR   NCBIfam; TIGR00664; DNA_III_psi; 1.
DR   NCBIfam; NF005339; holD; 1.
DR   NCBIfam; NF005336; PRK06856.1-2; 1.
DR   Pfam; PF03603; DNA_III_psi; 1.
DR   PIRSF; PIRSF029225; DNA_pol_III_psi; 1.
DR   SUPFAM; SSF102220; DNA polymerase III psi subunit; 1.
PE   1: Evidence at protein level;
KW   3D-structure; DNA replication; DNA-directed DNA polymerase;
KW   Nucleotidyltransferase; Reference proteome; Transferase.
FT   CHAIN           1..137
FT                   /note="DNA polymerase III subunit psi"
FT                   /id="PRO_0000105520"
FT   HELIX           4..12
FT                   /evidence="ECO:0007829|PDB:8GJ2"
FT   STRAND          17..20
FT                   /evidence="ECO:0007829|PDB:8GJ2"
FT   HELIX           22..24
FT                   /evidence="ECO:0007829|PDB:8GJ2"
FT   HELIX           31..34
FT                   /evidence="ECO:0007829|PDB:1EM8"
FT   STRAND          39..42
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           52..61
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           65..67
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   STRAND          68..71
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           73..76
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   STRAND          87..91
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   STRAND          97..100
FT                   /evidence="ECO:0007829|PDB:1EM8"
FT   STRAND          102..105
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           108..113
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           115..127
FT                   /evidence="ECO:0007829|PDB:3SXU"
FT   HELIX           129..132
FT                   /evidence="ECO:0007829|PDB:3SXU"
SQ   SEQUENCE   137 AA;  15174 MW;  5B7356201E7E27FE CRC64;
     MTSRRDWQLQ QLGITQWSLR RPGALQGEIA IAIPAHVRLV MVANDLPALT DPLVSDVLRA
     LTVSPDQVLQ LTPEKIAMLP QGSHCNSWRL GTDEPLSLEG AQVASPALTD LRANPTARAA
     LWQQICTYEH DFFPRND
//