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DNA polymerase III subunit beta
E coli beta clamp 1MMI.png
Crystallographic structure of the dimeric DNA polymerase beta subunit from E. coli.[1]
Organism Escherichia coli
(str. K-12 substr. MG1655)
Symbol dnaN
Entrez 948218
RefSeq (Prot) NP_418156
UniProt P0A988
Other data
EC number
Chromosome MG1655: 3.88 - 3.88 Mb

dnaN is the gene that codes for the DNA clamp (also known as β sliding clamp) of DNA polymerase III in prokaryotes.[2][3] The β clamp physically locks Pol III onto a DNA strand during replication to help increase its processivity.[4] The eukaryotic equivalent to the β clamp is PCNA.

See also[edit]


  1. ^ PDB: 1MMI​; Oakley AJ, Prosselkov P, Wijffels G, Beck JL, Wilce MC, Dixon NE (July 2003). "Flexibility revealed by the 1.85 Å crystal structure of the beta sliding-clamp subunit of Escherichia coli DNA polymerase III". Acta Crystallogr. D. 59 (Pt 7): 1192–9. doi:10.1107/S0907444903009958. PMID 12832762. 
  2. ^ Ohmori H, Kimura M, Nagata T, Sakakibara Y (May 1984). "Structural analysis of the dnaA and dnaN genes of Escherichia coli". Gene. 28 (2): 159–70. doi:10.1016/0378-1119(84)90253-1. PMID 6234204. 
  3. ^ Armengod ME, García-Sogo M, Lambíes E (August 1988). "Transcriptional organization of the dnaN and recF genes of Escherichia coli K-12". J. Biol. Chem. 263 (24): 12109–14. PMID 2841344. 
  4. ^ Stukenberg PT, Studwell-Vaughan PS, O'Donnell M (June 1991). "Mechanism of the sliding beta-clamp of DNA polymerase III holoenzyme". J. Biol. Chem. 266 (17): 11328–34. PMID 2040637.