Summary: Ku70/Ku80 beta-barrel domain
This is the Wikipedia entry entitled "Ku (protein)". More...
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Ku (protein) Edit Wikipedia article
|PDB||1JEY (RCSB PDB PDBe PDBj)|
|Locus||Chr. 2 q35|
|Alt. symbols||Ku70, G22P1|
|PDB||1JEY (RCSB PDB PDBe PDBj)|
|Locus||Chr. 22 q11-q13|
|Ku70/Ku80 N-terminal alpha/beta domain|
crystal structure of the ku heterodimer
|Ku70/Ku80 beta-barrel domain|
crystal structure of the ku heterodimer bound to dna
|Ku70/Ku80 C-terminal arm|
crystal structure of the ku heterodimer bound to dna
|Ku C terminal domain like|
the 3d solution structure of the c-terminal region of ku86
Ku is a protein that binds to DNA double-strand break ends and is required for the non-homologous end joining (NHEJ) pathway of DNA repair. Ku is evolutionarily conserved from bacteria to human. The ancestral bacterial Ku is a homodimer (two copies of the same protein bound to each other). Eukaryotic Ku is a heterodimer of two polypeptides, Ku70 (XRCC6) and Ku80 (XRCC5), so named because the molecular weight of the human Ku proteins is around 70 kDa and 80 kDa. The two Ku subunits form a basket-shaped structure that threads onto the DNA end. Once bound, Ku can slide down the DNA strand, allowing more Ku molecules to thread onto the end. In higher eukaryotes, Ku forms a complex with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form the full DNA-dependent protein kinase, DNA-PK. Ku is thought to function as a molecular scaffold to which other proteins involved in NHEJ can bind.
In many organisms, Ku has additional functions at telomeres in addition to its role in DNA repair.
Abundance of Ku80 seems to be related to species longevity.
The Ku70 and Ku80 proteins consist of three structural domains. The N-terminal domain is an alpha/beta domain. This domain only makes a small contribution to the dimer interface. The domain comprises a six stranded beta sheet of the Rossman fold. The central domain of Ku70 and Ku80 is a DNA-binding beta-barrel domain. Ku makes only a few contacts with the sugar-phosphate backbone, and none with the DNA bases, but it fits sterically to major and minor groove contours forming a ring that encircles duplex DNA, cradling two full turns of the DNA molecule. By forming a bridge between the broken DNA ends, Ku acts to structurally support and align the DNA ends, to protect them from degradation, and to prevent promiscuous binding to unbroken DNA. Ku effectively aligns the DNA, while still allowing access of polymerases, nucleases and ligases to the broken DNA ends to promote end joining. The C-terminal arm is an alpha helical region which embraces the central beta-barrel domain of the opposite subunit. In some cases a fourth domain is present at the C-terminus, which binds to DNA-dependent protein kinase catalytic subunit.
- PDB 1JEY; Walker JR, Corpina RA, Goldberg J (August 2001). "Structure of the Ku heterodimer bound to DNA and its implications for double-strand break repair". Nature 412 (6847): 607–14. doi:10.1038/35088000. PMID 11493912.
- Doherty AJ, Jackson SP, Weller GR (July 2001). "Identification of bacterial homologues of the Ku DNA repair proteins". FEBS Lett. 500 (3): 186–8. doi:10.1016/S0014-5793(01)02589-3. PMID 11445083.
- Carter T, Vancurová I, Sun I, Lou W, DeLeon S (December 1990). "A DNA-activated protein kinase from HeLa cell nuclei". Mol. Cell. Biol. 10 (12): 6460–71. PMC 362923. PMID 2247066.
- Difilippantonio MJ, Zhu J, Chen HT, Meffre E, Nussenzweig MC, Max EE, Ried T, Nussenzweig A (March 2000). "DNA repair protein Ku80 suppresses chromosomal aberrations and malignant transformation". Nature 404 (6777): 510–4. doi:10.1038/35006670. PMID 10761921.
- Ferguson DO, Sekiguchi JM, Chang S, Frank KM, Gao Y, DePinho RA, Alt FW (June 2000). "The nonhomologous end-joining pathway of DNA repair is required for genomic stability and the suppression of translocations". Proc. Natl. Acad. Sci. U.S.A. 97 (12): 6630–3. doi:10.1073/pnas.110152897. PMC 18682. PMID 10823907.
- Boulton SJ, Jackson SP (March 1998). "Components of the Ku-dependent non-homologous end-joining pathway are involved in telomeric length maintenance and telomeric silencing". EMBO J. 17 (6): 1819–28. doi:10.1093/emboj/17.6.1819. PMC 1170529. PMID 9501103.
- Lorenzini A, Johnson FB, Oliver A, Tresini M, Smith JS, Hdeib M, Sell C, Cristofalo VJ, Stamato TD (Nov–Dec 2009). "Significant Correlation of Species Longevity with DNA Double Strand Break-Recognition but not with Telomere Length". Mech Ageing Dev. 130 (11–12): 784–92. doi:10.1016/j.mad.2009.10.004. PMC 2799038. PMID 19896964.
- Sugihara T, Wadhwa R, Kaul SC, Mitsui Y (April 1999). "A novel testis-specific metallothionein-like protein, tesmin, is an early marker of male germ cell differentiation". Genomics 57 (1): 130–6. doi:10.1006/geno.1999.5756. PMID 10191092.
- Aravind L, Koonin EV (August 2001). "Prokaryotic homologs of the eukaryotic DNA-end-binding protein Ku, novel domains in the Ku protein and prediction of a prokaryotic double-strand break repair system". Genome Res. 11 (8): 1365–74. doi:10.1101/gr.181001. PMC 311082. PMID 11483577.
- Harris R, Esposito D, Sankar A, Maman JD, Hinks JA, Pearl LH, Driscoll PC (January 2004). "The 3D solution structure of the C-terminal region of Ku86 (Ku86CTR)". J. Mol. Biol. 335 (2): 573–82. doi:10.1016/j.jmb.2003.10.047. PMID 14672664.
Ku70/Ku80 beta-barrel domain Provide feedback
The Ku heterodimer (composed of Ku70 P12956 and Ku80 P13010) contributes to genomic integrity through its ability to bind DNA double-strand breaks and facilitate repair by the non-homologous end-joining pathway. This is the central DNA-binding beta-barrel domain. This domain is found in both the Ku70 P12956 and Ku80 P13010 proteins that form a DNA binding heterodimer .
Aravind L, Koonin EV; , Genome Res 2001;11:1365-1374.: Prokaryotic homologs of the eukaryotic DNA-end-binding protein Ku, novel domains in the Ku protein and prediction of a prokaryotic double-strand break repair system. PUBMED:11483577 EPMC:11483577
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR006164
The Ku heterodimer is composed of Ku70 and Ku80 (or Ku86), 70 kDa and 80 kDa subunits of an ATP-dependent DNA helicase, which contributes to genomic integrity through its ability to bind DNA double-stranded breaks and facilitate repair by the non-homologous end-joining pathway. This is the central DNA-binding beta-barrel domain and is found in both the Ku70 and Ku80 proteins. Ku makes only a few contacts with the sugar-phosphate backbone, and none with the DNA bases, but it fits sterically to major and minor groove contours forming a ring that encircles duplex DNA, cradling two full turns of the DNA molecule. By forming a bridge between the broken DNA ends, Ku acts to structurally support and align the DNA ends, to protect them from degradation, and to prevent promiscuous binding to unbroken DNA. Ku effectively aligns the DNA, while still allowing access of polymerases, nucleases and ligases to the broken DNA ends to promote end joining [PUBMED:11483577].
|Molecular function||DNA binding (GO:0003677)|
|ATP-dependent DNA helicase activity (GO:0004003)|
|Biological process||double-strand break repair via nonhomologous end joining (GO:0006303)|
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Curation and family details
|Seed source:||Bateman A|
|Number in seed:||29|
|Number in full:||1701|
|Average length of the domain:||191.60 aa|
|Average identity of full alignment:||20 %|
|Average coverage of the sequence by the domain:||42.31 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||11|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Ku domain has been found. There are 4 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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