Structural highlights
Function
[DPO3A_ECOLI] DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. The alpha chain is the DNA polymerase. [DPO3E_ECOLI] DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. The epsilon subunit contain the editing function and is a proofreading 3'-5' exonuclease. [DPO3B_ECOLI] DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. The beta chain is required for initiation of replication once it is clamped onto DNA, it slides freely (bidirectional and ATP-independent) along duplex DNA.
Publication Abstract from PubMed
The replicative DNA polymerase PolIIIalpha from E. coli is a uniquely fast and processive enzyme. For its activity it relies on the DNA sliding clamp beta, the proofreading exonuclease epsilon and the C-terminal domain of the clamp loader subunit tau. Due to the dynamic nature of the four-protein complex it has long been refractory to structural characterization. Here we present the 8 A resolution cryo-electron microscopy structures of DNA-bound and DNA-free states of the PolIII-clamp-exonuclease-tauc complex. The structures show how the polymerase is tethered to the DNA through multiple contacts with the clamp and exonuclease. A novel contact between the polymerase and clamp is made in the DNA bound state, facilitated by a large movement of the polymerase tail domain and tauc. These structures provide crucial insights into the organization of the catalytic core of the replisome and form an important step towards determining the structure of the complete holoenzyme.
cryo-EM structures of the E. coli replicative DNA polymerase reveal dynamic interactions with clamp, exonuclease and tau.,Fernandez-Leiro R, Conrad J, Scheres SH, Lamers MH Elife. 2015 Oct 24;4. pii: e11134. doi: 10.7554/eLife.11134. PMID:26499492[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Fernandez-Leiro R, Conrad J, Scheres SH, Lamers MH. cryo-EM structures of the E. coli replicative DNA polymerase reveal dynamic interactions with clamp, exonuclease and tau. Elife. 2015 Oct 24;4. pii: e11134. doi: 10.7554/eLife.11134. PMID:26499492 doi:http://dx.doi.org/10.7554/eLife.11134
