1em8: Difference between revisions
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'''Crystal structure of chi and psi subunit heterodimer from DNA POL III''' | {{Structure | ||
|PDB= 1em8 |SIZE=350|CAPTION= <scene name='initialview01'>1em8</scene>, resolution 2.1Å | |||
|SITE= | |||
|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] | |||
|GENE= | |||
}} | |||
'''Crystal structure of chi and psi subunit heterodimer from DNA POL III''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1EM8 is a [ | 1EM8 is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1EM8 OCA]. | ||
==Reference== | ==Reference== | ||
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:[http:// | 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:[http://www.ncbi.nlm.nih.gov/pubmed/14717711 14717711] | ||
[[Category: DNA-directed DNA polymerase]] | [[Category: DNA-directed DNA polymerase]] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
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[[Category: heterodimer]] | [[Category: heterodimer]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:57:27 2008'' | ||
Revision as of 11:57, 20 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 | ||||||
| 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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