1em8: Difference between revisions
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|SITE= | |SITE= | ||
|LIGAND= | |LIGAND= | ||
|ACTIVITY= [http://en.wikipedia.org/wiki/DNA-directed_DNA_polymerase DNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.7 2.7.7.7] | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/DNA-directed_DNA_polymerase DNA-directed DNA polymerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.7.7 2.7.7.7] </span> | ||
|GENE= | |GENE= | ||
|DOMAIN=<span class='plainlinks'>[http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?uid=pfam04364 DNA_pol3_chi], [http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?uid=COG3050 HolD]</span> | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1em8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1em8 OCA], [http://www.ebi.ac.uk/pdbsum/1em8 PDBsum], [http://www.fli-leibniz.de/cgi-bin/ImgLib.pl?CODE=1kfv JenaLib], [http://www.rcsb.org/pdb/explore.do?structureId=1em8 RCSB]</span> | |||
}} | }} | ||
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[[Category: heterodimer]] | [[Category: heterodimer]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Mar 26 05:51:51 2008'' | ||
Revision as of 06:51, 26 March 2008
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| , resolution 2.1Å | |||||||
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| Activity: | DNA-directed DNA polymerase, with EC number 2.7.7.7 | ||||||
| Domains: | DNA_pol3_chi, HolD | ||||||
| Resources: | FirstGlance, OCA, PDBsum, JenaLib, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of chi and psi subunit heterodimer from DNA POL III
OverviewOverview
The chi (chi) and psi (psi) subunits of Escherichia coli DNA polymerase III form a heterodimer that is associated with the ATP-dependent clamp-loader machinery. In E. coli, the chi:psi heterodimer serves as a bridge between the clamp-loader complex and the single-stranded DNA-binding protein. We determined the crystal structure of the chi:psi heterodimer at 2.1 A resolution. Although neither chi (147 residues) nor psi (137 residues) bind to nucleotides, the fold of each protein is similar to the folds of mononucleotide-(chi) or dinucleotide-(psi) binding proteins, without marked similarity to the structures of the clamp-loader subunits. Genes encoding chi and psi proteins are found to be readily identifiable in several bacterial genomes and sequence alignments showed that residues at the chi:psi interface are highly conserved in both proteins, suggesting that the heterodimeric interaction is of functional significance. The conservation of surface-exposed residues is restricted to the interfacial region and to just two other regions in the chi:psi complex. One of the conserved regions was found to be located on chi, distal to the psi interaction region, and we identified this as the binding site for a C-terminal segment of the single-stranded DNA-binding protein. The other region of sequence conservation is localized to an N-terminal segment of psi (26 residues) that is disordered in the crystal structure. We speculate that psi is linked to the clamp-loader complex by this flexible, but conserved, N-terminal segment, and that the chi:psi unit is linked to the single-stranded DNA-binding protein via the distal surface of chi. The base of the clamp-loader complex has an open C-shaped structure, and the shape of the chi:psi complex is suggestive of a loose docking within the crevice formed by the open faces of the delta and delta' subunits of the clamp-loader.
About this StructureAbout this Structure
1EM8 is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the chi:psi sub-assembly of the Escherichia coli DNA polymerase clamp-loader complex., Gulbis JM, Kazmirski SL, Finkelstein J, Kelman Z, O'Donnell M, Kuriyan J, Eur J Biochem. 2004 Jan;271(2):439-49. PMID:14717711
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